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Dissertations / Theses on the topic 'Hybrid Heterostructure Solar Cells'
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Vaynzof, Yana. "Inverted hybrid solar cells." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609823.
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Wong, Henry Mo Pun. "Semiconducting nanocrystals for hybrid solar cells." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613367.
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Levitsky, I. A. "Carbon Nanotubes - Si Hybrid Solar Cells." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35493.
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This short review describes recent results in the field of carbon nanotube (CNT) – Si hybrid photovolta-ics (PV) focusing on advantages of semiconducting carbon nanotubes over other organic materials used in organic- Si composite photosensing materials. Possible mechanisms of charge phogeneration at CNT- Si in-terface and chargte transport are discussed. Perspectives and future trends in research of this novel class of PV nanohybrids are presented as well.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35493
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Zhu, Mingxuan. "Silicon nanowires for hybrid solar cells." Ecole centrale de Marseille, 2013. http://tel.archives-ouvertes.fr/docs/00/94/57/87/PDF/The_manuscript-4.pdf.
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Noel, Nakita K. "Advances in hybrid solar cells : from dye-sensitised to perovskite solar cells." Thesis, University of Oxford, 2014. https://ora.ox.ac.uk/objects/uuid:e0f54943-546a-49cd-8fd9-5ff07ec7bf0a.
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This thesis presents a study of hybrid solar cells, specifically looking at various methods which can be employed in order to increase the power conversion efficiency of these devices. The experiments and results contained herein also present a very accurate picture of how rapidly the field of hybrid solar cells has progressed within the past three years. Chapters 1 and 2 present the background and motivation for the investigations undertaken, as well as the relevant theory underpinning solar cell operation. Chapter 2 also gives a brief review of the literature pertinent to the main types of devices investigated in this thesis; dye-sensitised solar cells, semiconductor sensitized solar cells and perovskite solar cells. Descriptions of the synthetic procedures, as well as the details of device fabrication and any measurement techniques used are outlined in Chapter 3. The first set of experimental results is presented in Chapter 4. This chapter outlines the synthesis of mesoporous single crystals (MSCs) of anatase TiO2 as well as an investigation of its electronic properties. Having shown that this material has superior electronic properties to the conventionally used nanoparticle films, they were then integrated into low temperature processed dye-sensitised solar cells and achieved power conversion efficiencies of > 3%, exhibiting electron transport rates which were orders of magnitude higher than those obtained for the high temperature processed control films. Chapter 5 further investigates the use of MSCs in photovoltaic devices, this time utilising a more strongly absorbing inorganic sensitiser, Sb2S3. Utilising the readily tunable pore size of MSCs, these Sb2S3 devices showed an increase in voltage and fill factor which can be attributed to a decrease in recombination within these devices. This chapter also presents the use of Sb2S3 in the meso-superstructured configuration. This device architecture showed consistently higher voltages suggesting that in this architecture, charge transport occurs through the absorber and not the mesoporous scaffold. Chapters 6 and 7 focus on the use of hybrid organic-inorganic perovskites in photovoltaic devices. In Chapter 6 the mixed halide, lead-based perovskite, CH3NH3PbI3-xClx is employed in a planar heterojunction device architecture. The effects of Lewis base passivation on this material are investigated by determining the photoluminescence (PL) lifetimes and quantum efficiencies of treated and untreated films. It is found that passivating films of this material using Lewis bases causes an increase in the PLQE at low fluences as well as increasing the PL lifetime. By globally fitting these results to a model the trap densities are extracted and it is found that using these surface treatments decreases the trap density of the perovskite films. Finally, these treatments are used in complete solar cells resulting in increased power conversion efficiencies and an improvement in the stabilised power output of the devices. Chapter 7 describes the materials synthesis and characterisation of the tin-based perovskite CH3NH3SnI3 and presents the first operational, lead-free perovskite solar cell. The work presented in this thesis describes significant advances in the field of hybrid solar cells, specifically with regards to improvements made to the nanostructured electrode, and the development and implementation of more highly absorbing sensitizers. The improvements discussed here will prove to be quite important in the drive towards exploiting solar power as a clean, affordable source of energy.
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Ishwara, Thilini W. S. "Optimisation of hybrid organic/ inorganic solar cells." Thesis, Imperial College London, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510746.
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Böhm, Marcus. "Hybrid ligands in quantum dot solar cells." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708460.
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Lentz, Levi (Levi Carl). "Rational design of hybrid organic solar cells." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92219.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 113-117).
In this thesis, we will present a novel design for a nano-structured organic-inorganic hybrid photovoltaic material that will address current challenges in bulk heterojunction (BHJ) organic-based solar cell materials. Utilizing first principles Density Functional Theory (DFT), we show that layered inorganic phosphates and tradition organic dyes can be combined to form a new class of bulk heterojunction photovoltaic with high electron and hole mobilities with low exciton recombination, potentially enabling very high efficiency with existing organic-based solar-cell molecules. We will discuss the physical origin of these properties and investigate several approaches for engineering the electronic structure of these materials. By using these methods, it will be possible to engineer the transport and optical properties of these materials, with potential applications beyond photovoltaics in areas from organic electronics to photoactuators.
by Levi Lentz.
S.M.
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Weickert, Jonas [Verfasser]. "Nanostructured Interfaces in Hybrid Solar Cells / Jonas Weickert." Konstanz : Bibliothek der Universität Konstanz, 2014. http://d-nb.info/1058326031/34.
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Cacovich, Stefania. "Electron microscopy studies of hybrid perovskite solar cells." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/276753.
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Over the last five years hybrid organic-inorganic metal halide perovskites have attracted strong interest in the solar cell community as a result of their high power conversion efficiency and the solid opportunity to realise a low-cost as well as industry-scalable technology. Nevertheless, several aspects of this novel class of materials still need to be explored and the level of our understanding is rapidly and constantly evolving, from month to month. This dissertation reports investigations of perovskite solar cells with a particular focus on their local chemical composition. The analytical characterisation of such devices is very challenging due to the intrinsic instability of the organic component in the nanostructured compounds building up the cell. STEM-EDX (Scanning Transmission Electron Microscopy - Energy Dispersive X-ray spectroscopy) was employed to resolve at the nanoscale the morphology and the elemental composition of the devices. Firstly, a powerful procedure, involving FIB (Focus Ion Beam) sample preparation, the acquisition of STEM-EDX maps and the application of cutting edge post-processing data techniques based on multivariate analysis was developed and tested. The application of this method has drastically improved the quality of the signal that can be extracted from perovskite thin films before the onset of beam-induced transformations. Morphology, composition and interfaces in devices deposited by using different methodologies and external conditions were then explored in detail by combining multiple complementary advanced characterisation tools. The observed variations in the nanostructure of the cells were related to different photovoltaic performance, providing instructive indications for the synthesis and fabrication routes of the devices. Finally, the main degradation processes that affect perovskite solar cells were probed. STEM-EDX was used in conjunction with the application of in situ heating, leading to the direct observation of elemental species migration within the device, reported here for the first time with nanometric spatial resolution. Further analyses, involving a set of experiments aimed to study the effects of air exposure and light soaking on the cells, were designed and performed, providing evidence of the main pathways leading to the drastic drop in the device performance.
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Xu, Huajun. "Near-IR Dye Sensitization of Polymer Solar Cells." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188604.
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Dickerson, Jeramy Ray. "Heterostructure polarization charge engineering for improved and novel III-V semiconductor devices." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51793.
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Innovative electronic device concepts that use polarization charges to provide improved performance were validated. The strength of the electric fields created by polarization charges (PCs) was suggested to act as an additional design parameter in the creation of devices using III-nitride and other highly polar materials. Results indicated that polarization induced electric fields can replace conventional doping schemes to create the charge separation region of solar cells and would allow for a decoupling of device performance from doping requirements. Additionally, a model for calculating current through polarization induced tunnel diodes was proposed. The model was found to agree well with experimental current values. Several polarization induced tunnel junction (PTJ) designs were analyzed. A novel double-barrier PTJ was conceived that would allow for the creation of a multi-junction solar cell using strained InGaN absorption layers. Future research would include the fabrication of these devices and the inclusion of thermal effects in the model for calculating current through PTJs.
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Hyung, Do Kim. "Development of Highly Efficient Organic-Inorganic Hybrid Solar Cells." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225630.
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MacLachlan, Andrew. "Tuning morphology of hybrid organic/metal sulfide solar cells." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/25766.
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This thesis explores the influence that morphology plays in hybrid organic/inorganic solar cells. This is studied for a range of different materials systems. A series of cadmium xanthate complexes were synthesised, for use as in-situ precursors to CdS nanoparticles in hybrid poly(3-hexylthiophene-2,5-diyl (P3HT)/CdS solar cells. The heterojunction morphology of these hybrid P3HT/CdS blends was found to be dependent on the ligand moiety of the precursor used. The formation of CdS domains was studied by time-resolved materials characterisation techniques and directly imaged using electron microscopy. A combination of transient absorption spectroscopy (TAS) and photovoltaic device performance measurements was used to show the intricate balance required between charge photogeneration and having percolated domains in order to effectively extract charges to maximize device power conversion efficiencies. An analogous method was also applied to a P3HT/Sb_2 S_3 system. Following on from the previous work, a non-toxic alternative to CdS and Sb2S3 was explored. Bismuth xanthates were thermally decomposed to form hybrid polymer/Bi_2 S_3 heterojunctions with two distinctly different morphologies. The bismuth xanthates were found to form nanorods in-situ, within the solid-state polymer matrix, as well as mesostructured arrays of Bi_2 S_3 rods that were later infiltrated with a polymer, using a two-step method. TAS was used to study the charge generation yield in both these systems and hybrid photovoltaic devices were also fabricated. Finally, through a collaboration with The Institute of Photonic Sciences (ICFO), TAS was used to study two separate organic semiconductor/Bi_2 S_3 BHJs. The first of which was a P3HT/Bi_2 S_3 nanoparticle blend solar cell. The charge generation yield in this system was investigated and then compared to a novel thiol-functionalised P3HT based block copolymer (P3HT-SH). Secondly, TAS was used to obtain a better understanding of the charge transfer at several interfaces in a vertically structured Bi_2 S_3 nanorod array that was filled with 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (SPIRO).
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Lander, Sanna. "Polymer/silicon hybrid solar cells : Fabrication and electrical properties." Thesis, Karlstads universitet, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-46945.
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In this thesis, the process of fabricating PEDOT:PSS/c-Si hybrid solar cells has been investigated with the goal of performing a proof of concept as well as to determine the influence on solar cell performance of some processing parameters. Properties of PEDOT:PSS film formation and metal contact formation were investigated as a first step. Additionally, the surface passivation properties of PEDOT:PSS on n-Si have been studied and carrier lifetimes of 300 I denna uppsats har tillverkningen av PEDOT:PSS/c-Si hybridsolceller undersökts med målet att tillverka en fungerande solcell samt att bestämma påverkan på cellens prestanda av vissa processparametrar. Polymerfilmbildning och metallkontaktbildning undersöktes som ett första steg. Dessutom studerades polymerfilmens förmåga att passivera n-Si ytor, och livstider hos laddningsbärare på ca 300
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Zimmermann, Eugen [Verfasser]. "Interfacial Metal Oxides for Hybrid Solar Cells / Eugen Zimmermann." Konstanz : KOPS Universität Konstanz, 2019. http://d-nb.info/1235327345/34.
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Manaf, Nor Azlian Binti Abdul. "Organic/inorganic hybrid solar cells based on electroplated CdTe." Thesis, Sheffield Hallam University, 2015. http://shura.shu.ac.uk/20010/.
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The purpose of this work is to develop organic/inorganic hybrid solar cells based on electroplated CdTe. The materials used in this research are CdS, CdTe and PAni. These materials have been characterised by XRD, Raman spectroscopy, EDX, SEM, AFM, UV-Vis spectroscopy, PEC, C-V and DC measurements, UPS and PL for their structural, compositional, morphological, optical, electrical and defect properties. CdS has electrodeposited from the electrolyte using (NH[4])[2]S[2]O[3] as the sulphur source. The optimum growth voltage (V[g]) and temperature (T[g]) are obtained at 1455 mV and 85°C, respectively. The best annealing condition is found to be at 400°C for 20 minutes in the presence of CdCl[2]+CdF[2]. CdTe thin films were electrodeposited from CdCl[2] precursor and a comprehensive study was carried out for the first time. The work has demonstrated a better understanding of material issues and some clues on the effect of CdCl[2] treatment. The optimum V[g] and annealing condition were obtained at 698 mV with respect to the calomel electrode and 420°C for 20 minutes in the presence of CdCl[2]+CdF[2] or CdCl[2]+CdF[2]+GaCl[3]. The development of PAni thin films has been established using anodic and cathodic deposition. The pernigraniline salt PAni grown from anodic has an amorphous structure, large bandgap and cementing growth effect while leucoemeraldine salt PAni grown from cathodic deposition shows the best crystallinity at V[g]=1654 mV with respect to carbon anode, smaller grain size, higher resistivity and lower bandgap. The CdS, CdTe and PAni thin films have been studied in device structures, assessing their solar cell device performance. The best of CdS/CdTe solar cell was observed with efficiency of 5.8% when using CdS thin film treated with CdCl[2]+CdF[2] at 400°C. The best solar cell from CdTe study shows the efficiency of 6.8% when using CdTe thin films treated with CdCl[2]+CdF[2] at 420°C. Further study demonstrates that a device with g/FTO/n-CdS(~200 nm)/n-CdTe(~1200 nm)/p-CdTe(~300 nm)/Au shows high J[sc] and highest efficiency (7.7%) due to the formation of n-n heterojunction, p-n homojuction and ohmic contact within the structure. The efficiency of the solar cell increased from -2.4% to -4.2% when incorporating -81 nm thick PAni layer grown from anodic deposition. The devices incorporating ZnS, ZnTe and CdSe layers show the prospect of graded bandgap solar cell, but proper optimisation on each material should be carried out before using in multi-layer device structures. The study on the lifetime of solar cells show slow degradation and it maintained more than 83% of its initial efficiency after 9,000 hours.
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DIANETTI, MARTINA. "Transparent Conductive Oxide-free hybrid and organic solar cells." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2014. http://hdl.handle.net/2108/202335.
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In organic Bulk Hetero Junction (BHJ) and hybrid/perovskite solar cells, the most employed material used as transparent electrode for the charges collection is transparent conductive oxide (TCO) such as indium doped tin oxide (ITO) or fluorine doped tin oxide (FTO). Beside the high transparency and conductivity (80% on glass substrates and 15 Ω/□, respectively) of ITO and FTO, there are many critical issues: i) limited indium sources, ii) high cost due to the deposition techniques (sputtering, evaporation, pulsed laser deposition and electroplating etc.), iii) high temperature processing and iv) high mechanical brittleness. For these reasons, it is necessary to investigate new materials.
The discovery of graphene, in 2004, that led Novoselov and Geim to win the Nobel Prize has opened up new areas of scientific research. In particular, its surprising physical, optical, mechanical and electrical properties have made the graphene one of the most promising material in the modern electronic applications and in particular in the 3rd generation solar cells technology that can be produced cheaply and very fast from solution with printing processes both on plastic and rigid substrates.
This work is mainly focused on the use of graphene as a replacement of the conventional transparent conductive oxides. In particular, most of the problems (wettability, annealing temperature etc.) for fabricate solar cells on graphene electrodes were solved. A simple way to decrease the sheet resistance of graphene electrode, by the addition of a metal grid, is presented as well. With the aim to realize high efficiency solar cells, both BHJ with low band gap polymers as active layer and perovskite-based solar cells have been investigated. Firstly, the effects of two different materials (Ni and MoO3), used as p-dopant on bare graphene, were studied and the thickness was optimized in order to reduce the graphene sheet resistance and increase the solar cells performances. Moreover, was investigated the feasibility to realize graphene-based solar cells starting to optimize the deposition of the organic active layer material (blend of P3HT: PC [60] BM or PTB7: PC [70] BM) in terms of annealing temperature and thickness.
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Furthermore, in order to increase the solar cells efficiency, organic-inorganic perovskite ( CH3NH3PbI3-xClx ) material was studied as active layer. As first step, the growth of perovskite active layer was optimized in terms of annealing temperature, photoluminescence and morphology both for direct and inverted architectures. Then, using a planar direct structure, efforts were made to solve the issues related to the realization of perovskite solar cells on graphene electrode. While, in the direct structure, Titania ordered photonics nanostructures were introduced as electron transporting layer (ETL) to increase the light absorbed by the perovskite active layer and the photo-generated current in the solar cells.
With the view to replace the conventional transparent conductive electrode, conductive polymers were also investigated. The most promising organic material is PEDOT: PSS, which is a semitransparent and conductive polymer. However, the pristine PEDOT: PSS film, deposited from aqueous solution, has a lower conductivity than the conventional transparent conductive oxide. For this reason, many strategies have been employed to improve the conductivity of this material to obtain a low cost, low temperature and TCO-free perovskite planar heterojunction solar cells on flexible substrate. In particular, it is demonstrated that the highly conductive polymeric material shows potential as a practical replacement for expensive and brittle ITO/PET. Moreover, in the bending test, the ITO-free perovskite solar cells with PEDOT anodes on flexible substrate manifested superior mechanical robustness compared with ITO-based cells, showing the high flexibility of perovskite layer.
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Hofer, Sandra. "Synthesis and characterisation of CuInS₂-nanoparticles for hybrid solar cells." Linz : Johannes Kepler Universität Linz, 2005. http://www.lios.at/Publications/thesis/thesis-hofer.pdf.
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Iza, Schmidt Diana Cristina. "Nanostructuring and processing of metal oxides in hybrid solar cells." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610689.
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Hey, Andrew Stuart. "Series interconnects and charge extraction interfaces for hybrid solar cells." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:f19e44a8-e394-4859-9649-734116bc22b8.
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This thesis investigates novel hole extraction interfaces and series interconnects for applications in organic photovoltaics, specifically in single junction solid-state dye-sensitized solar cells (DSSCs) and tandem DSSC/polymer bulk heterojunction solar cells. Improvements in hole extraction and device performance by using materials compatible with scalable deposition methods are presented, including tungsten- and molybdenum-disulphide (WS2 and MoS2), and p-type doped spiro-OMeTAD (2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)9,9'-spirobifluorene) nanoparticle dispersions. WS2 and MoS2 hole extraction layers increase averaged short circuit currents by 20% and 16% respectively, and power conversion efficiencies by 19% and 14% respectively when compared with control devices. Similarly, doped spiro-OMeTAD nano-particle layers improved short circuit current densities by 32% and efficiencies by 9%. Tandem device interconnects using these novel hole extraction formats have been fabricated, but although devices did exhibit rectification, overall performance was poor. Possible reasons for their limited success have been analysed. Dye-sensitized solar mini-modules are also reported. In order to assure the scalability of DSSC technology, these larger area devices were constructed using doctor blade coating to deposit the hole transporter material. As well as achieving a respectable maximum power conversion efficiency of 2.6%, it has also been shown that the extent to which hole transporter infiltrates the mesoporous photoanode of these devices may be tuned by altering substrate temperature during deposition. It was found that an optimal coating temperature of 70 degrees C produced the best efficiency, with a corresponding pore-filling fraction of 41%.
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Desta, Derese Gugsa. "Study of air-processed Si-NC/P3HT hybrid solar cells." Master's thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/6451.
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Mestrado em Ciência e Engenharia dos MateriaisNeste trabalho são estudadas células solares híbridas formadas por poli(3- hexiltiofeno-2,5-diyl) (P3HT) como condutor orgânico de buracos e nanocristais de silício (Si-NCs) como conductor de electrões inorgânico. Células solares híbridas têm atraído muita atenção nos últimos anos devido ao facto de serem potencialmente fabricadas a baixo custo, a sua flexibilidade e baixo peso. As possibilidades de processamento em solução e ajuste da região espectral de absorção, a baixa toxicidade, e a abundância fazem dos Si-NCs um material atractivo para aplicação em células solares. Si-NCs de elevada qualidade podem hoje em dia ser produzidos em larga escala a partir da fase gasosa através da decomposição de silano num plasma. Embora a superfícies destes Si-NCs seja terminada com ligações Si-H durante a sua síntese, estes desenvolvem uma camada de óxido na superfície quando são expostos ao ar. Até agora, células híbridas de Si-NC/P3HT foram fabricadas com Si- NCs que não foram expostos ao ar após a sua síntese e foram posteriormente estudadas em condições de atmosfera inerte, devido à expectativa de que a exposição ao ar resulta na sua degradação. No entanto, o processamento de dispositivos em atmosfera inerte impõe limitações em termos técnicos e custo. Nesta tese estudamos o efeito do processamento em atmosfera de ar na performance e degradação de células solares híbridas de Si-NC/P3HT. As células foram fabricadas em ar e em atmosfera de azoto e caracterizadas à temperatura ambiente e condições de exposição ao ar. Para produzir a células solares foram usados Si-NCs que foram expostos ao ar após a síntese e que por isso contêm uma camada de óxido na sua superfície. Para remover esta camada, nós usamos um método de erosão química com uma solução diluída de ácido hidroflurico (HF). Células solares fabricadas com uma mistura de 1:1 em percentagem de peso (wt.%) de Si-NC:P3HT não revelaram qualquer efeito fotovoltaico. Dispositivos fabricados com uma mistura de 2:1 wt.% de Si-NC:P3HT mostraram efeito fotovoltaico, devido à formação de uma rede interpenetrara de Si-NC e P3HT em toda a extensão do filme foto activo, tal como revelado em imagens de microscopia electrónica de varrimento. Dispositivos fabricados em atmosfera inerte não revelaram uma performance melhorada em relação aos dispositivos produzido em atmosfera de ar, indicando que a fabricação das células solares em ar não é o factor determinante da performance das nossas células solares. Células solares que mostraram um efeitos fotovoltaico degradaram-se rapidamente por exposição ao ar. Em contrate, filmes de P3HT e de misturas Si-NC/P3HT, estudados em experiências separadas, não revelaram uma degradação significativa por exposição ao ar. Estes resultados indicma que a degradação das células solares não deve resultar da degradação da camada foto activa de Si-NC/P3HT, mas poderá resultar da degradação de interfaces entre as varias camadas que compõem as células. Medidas de ressonância paramagnética electrónica (RPE) foram levadas a cabo com os Si-NCs usados nas nossas células e com Si-NCs usados para fabricar as células estudadas em trabalhos publicados anteriormente por outros grupos. Estas medidas revelaram que o número de defeitos superficiais por nanocristal nos nossos Si-NCs é cerca de três ordens de grandeza superior ao número encontrado nos Si- NCs usados anteriormente. Este facto poderá explicar a baixa performance fotovoltaica os nossos dispositivos.
We study-air-processed organic-inorganic hybrid solar cells, which incorporate poly(3-hexylthiophene-2,5-diyl) (P3HT) as organic hole conductor and silicon nanocrystals (Si-NCs) as inorganic electron conductor. Hybrid solar cells have received a lot of attention in recent years due to their low cost, flexibility and lightweight. Solution processability, nontoxicity, abundance and tunable absorption spectral range of Si-NCs make them attractive materials for application in solar cells. High quality Si-NCs can now a days be produced in large amounts from the gas phase decomposition of silane in a plasma. Although the surface of these Si-NCs is terminated with Si-H bonds immediately after synthesis, they develop an insulating native oxide shell after being exposed to air. So far, Si-NC/P3HT hybrid solar cells have only been fabricated using Si-NCs that have not been exposed to air after synthesis and afterwards characterized under inert atmosphere conditions due to the expectation that air exposure of the devices leads to their degradation. However, inert atmosphere processing has some technical and cost efficiency limitations. In this thesis, we study the effect of air-processing on the performance and degradation of solar cells based on Si-NC/P3HT. Hybrid solar cells were fabricated in air and under nitrogen ambient and characterized at room temperature under atmospheric air. To produce our solar cells we use Si-NCs that have been stored in air after plasma synthesis and, therefore, contain a native oxide at their surface. To remove this oxide layer we apply wet etching with a dilute hydrofluoric acid (HF) solution. Solar cells made from 1:1 wt.% (HF-etched Si-NC:P3HT) composition did not show detectable photovoltaic effect. A very small photovoltaic effect has been observed for devices made from 2:1 wt.% (HF-etched Si-NC:P3HT) composition as a result of the formation of an interpenetrated network throughout the photoactive film at higher NC concentration as seen from scanning electron microscopy. Device fabrication under inert atmosphere did not result in improved solar cell performance. This shows that fabrication of the devices in air was not the main reason for the poor performance of the hybrid solar cells. Moreover, solar cells that exhibited a photovoltaic effect were found to degrade within one day of air exposure. In contrast to this, the conductivity of P3HT, (unetched Si-NC)/P3HT and (HF-etched Si-NC)/P3HT films, studied in separate experiments, did not show significant degradation upon air exposure. These results indicate that the degradation of the solar cells is not due to degradation of individual photoactive layers, but could rather originate from degradation of interfaces between the different layers. Electron paramagnetic resonance measurements carried out with our Si- NCs and with Si-NCs used in previous investigations of Si-NC/P3HT solar cells revealed that the number of surface defects per NC is about three orders of magnitude larger in our NCs than in those used in the previous investigations. This could be a reason for the poor performance of our Si- NC/P3HT hybrid solar cells.
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Azzopardi, Brian. "Integration of hybrid organic-based solar cells for micro-generation." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/integration-of-hybrid-organicbased-solar-cells-for-microgeneration(6013d4a4-4702-4bfc-b3b3-c0ae155a83b9).html.
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Despite the fact that the global photovoltaic (PV) market has grown rapidly during the last two decades, driven by global climate change concerns and public policy supports of renewable energy sources, a PV system is still considered an expensive alternative energy source when compared to other sources of electricity. Emerging organic-based PV solar cells may lead to significant price reductions of a PV system. Though, in the short and medium term, the lifetime, efficiencies and reliability are expected to be lower than current commercially available silicon wafer-based and mature inorganic thin film PV modules.A consortium formed by inter-disciplinary scientists and engineers between the University of Manchester and Imperial College London was set-up to investigate organic-based hybrid solar cells. Potential solar cell materials with higher resultant conversion efficiency in research, targeting lower costs than other PV technologies were developed. The designs investigated feature hybrid organic-based quantum dot (QD) solar cells topology.This research seeks to integrate this new PV technology concept into future PV micro-generators. The challenges faced by emerging PV technologies with regard to PV module lifetime, efficiency and cost / price were summarised. The uniqueness of this work is that, throughout this research, the issues for commercialisation of emerging PV technologies for micro-generation; in particular with regards to low efficiency, short lifetime and high efficiency degradation, and low-cost / price were extensively analysed in every aspect.The technical, economic and also environmental viability perspectives of emerging PV technologies for micro-generation were found. A wide range of models and / or methodologies were developed, extended or applied for the first time to PV technologies for micro-generation, with particular focus where possible on the hybrid organic-based QD solar cells. Lifetime-adjusted calculations and life cycle costing were used to determine cost boundaries and PV electricity costs. Life cycle environmental impacts were determined by the use of life cycle analysis. A mixed integer single / multi-objective optimisation program was developed to determine optimal, compromise and trade-off relationships on PV system characteristics. These PV system characteristics, which are analysed on a systems level included module efficiency, grid interconnection rating, solar fraction, energy storage capacities, annualised life cycle costs, project worth value and environmental CO2 impacts / benefit. Finally, PV technologies for micro-generation were ranked by the use of multi-criteria decision analysis. The results clarify, inform and suggest concepts for emerging PV technologies integration for micro-generation by providing boundaries, trade-offs and suggestions to all stakeholder including commercial, domestic and public bodies.The direction for future research in emerging PV technologies for micro-generation is identified to be the development of customer decision tools for diversified PV technologies, policy adaptation for the inclusion of emerging PV technologies and large-scale manufacturing investigations on emerging PV modules that makes use of an organic-based PV technology.
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Sarvari, Hojjatollah. "FABRICATION AND CHARACTERIZATION OF ORGANIC-INORGANIC HYBRID PEROVSKITE SOLAR CELLS." UKnowledge, 2018. https://uknowledge.uky.edu/ece_etds/123.
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Solar energy as the most abundant source of energy is clean, non-pollutant, and completely renewable, which provides energy security, independence, and reliability. Organic-inorganic hybrid perovskite solar cells (PSCs) revolutionized the photovoltaics field not only by showing high efficiency of above 22% in just a few years but also by providing cheap and facile fabrication methods.
In this dissertation, fabrication of PSCs in both ambient air conditions and environmentally controlled N2-filled glove-box are studied. Several characterization methods such as SEM, XRD, EDS, Profilometry, four-point probe measurement, EQE, and current-voltage measurements were employed to examine the quality of thin films and the performance of the PSCs. A few issues with the use of equipment for the fabrication of thin films are addressed, and the solutions are provided.
It is suggested to fabricate PSCs in ambient air conditions entirely, to reduce the production cost. So, in this part, the preparation of the solutions, the fabrication of thin films, and the storage of materials were performed in ambient air conditions regardless of their humidity sensitivity. Thus, for the first part, the fabrication of PSCs in ambient air conditions with relative humidity above ~36% with and without moisture sensitive material, i.e., Li-TFSI are provided. Perovskite materials including MAPbI3 and mixed cation MAyFA(1-y)PbIxBr(1-x) compositions are investigated. Many solution-process parameters such as the spin-coating speed for deposition of the hole transporting layer (HTL), preparation of the HTL solution, impact of air and light on the HTL conductivity, and the effect of repetitive measurement of PSCs are investigated. The results show that the higher spin speed of PbI2 is critical for high-quality PbI2 film formation. The author also found that exposure of samples to air and light are both crucial for fabrication of solar cells with larger current density and better fill factor. The aging characteristics of the PSCs in air and vacuum environments are also investigated. Each performance parameter of air-stored samples shows a drastic change compared with that of the vacuum-stored samples, and both moisture and oxygen in air are found to influence the PSCs performances. These results are essential towards the fabrication of low-cost, high-efficiency PSCs in ambient air conditions.
In the second part, the research is focused on the fabrication of high-efficiency PSCs using the glove-box. Both single-step and two-step spin-coating methods with perovskite precursors such as MAyFA(1-y)PbIxBr(1-x) and Cesium-doped mixed cation perovskite with a final formula of Cs0.07MA0.1581FA0.7719Pb1I2.49Br0.51 were considered. The effect of several materials and process parameters on the performance of PSCs are investigated. A new solution which consists of titanium dioxide (TiO2), hydrochloric acid (HCl), and anhydrous ethanol is introduced and optimized for fabrication of quick, pinhole-free, and efficient hole-blocking layer using the spin-coating method. Highly reproducible PSCs with an average power conversion efficiency (PCE) of 15.4% are fabricated using this solution by spin-coating method compared to the conventional solution utilizing both spin-coating with an average PCE of 10.6% and spray pyrolysis with an average PCE of 13.78%. Moreover, a thin layer of silver is introduced as an interlayer between the HTL and the back contact. Interestingly, it improved the current density and, finally the PCEs of devices by improving the adhesion of the back electrode onto the organic HTL and increasing the light reflection in the PSC. Finally, a highly reproducible fabrication procedure for cesium-doped PSCs using the anti-solvent method with an average PCE of 16.5%, and a maximum PCE of ~17.5% is provided.
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Shen, Zhangfeng. "Engineering Carbon-Semiconductor Hybrid Materials for Photocatalysis and Solar Cells." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/66005.
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Carbon-semiconductor hybrid materials (CSHMs) are promising candidates for solar energy conversion because of their enhanced light harvesting ability and the prolonged charge carrier separation. In this thesis, a series of CSHMs has been successfully fabricated and applied in photocatalysis and dye-sensitized solar cells. The aim of this thesis is to develop cost-effective methods to prepare CSHMs with appropriate morphologies, compositions, and interfacial contact to promote the efficiency of photocatalysis and solar energy conversion.
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Unger, Eva. "XDSC : Excitonic Dye Solar Cells." Doctoral thesis, Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-168608.
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Solar energy is the foremost power source of our planet. Driving photosynthesis on our planet for 3 billion years the energy stored in the form of fossil fuels also originates from the sun. Consumption of fossil fuels to generate energy is accompanied with CO2 emission which affects the earth's climate in a serious manner. Therefore, alternative ways of converting energy have to be found. Solar cells convert sunlight directly into electricity and are therefore an important technology for future electricity generation. In this work solar cells based on the inorganic semiconductor titanium dioxide and hole-transporting dyes are investigated. These type of solar cells are categorized as hybrid solar cells and are conceptually related to both dye-sensitized solar cells and organic solar cells. Light absorption in the bulk of the hole-transporting dye layer leads to the formation of excitons that can be harvested at the organic/inorganic interface. Two design approaches were investigated: 1) utilizing a multilayer of a hole-transporting dye and 2) utilizing a hole-transporting dye as light harvesting antenna to another dye which is bound to the titanium dioxide surface. Using a multiple dye layer in titanium dioxide/hole transporting dye devices, leads to an improved device performance as light harvested in the consecutive dye layers can contribute to the photocurrent. In devices using both an inteface-bound dye and a hole-transporting dye, excitation energy can be transferred from the hole-transporting dye to the interface dye.
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Yao, Jizhong. "Studies of recombination in organic and hybrid solar cells using electroluminescence." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/52668.
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The performance of solution processed solar cells such as organic bulk heterojunction (OPV) devices is limited by strong recombination. However, the mechanisms are still unclear. In this thesis, I develop a toolbox using steady-state spectroscopy measurements to explore the recombination mechanisms in a range of solution-processed solar cells. In the first results chapter, I use the reciprocity relation between light absorption and light emission to explore theoretical and practical performance limits for solar cells based on organic semiconductors and perovskites and compare the results with data for state-of-the-art photovoltaic cells made from GaAs, c-Si, and CIGS. In OPV systems, I show that the energetic losses due to the mismatch of the bandgap have been significantly reduced through optimisation of the donor polymer, but the non-radiative recombination losses remain the same and become the major barrier to higher performance. In the next two chapters, I use light intensity dependence of open-circuit voltage measurement (suns-VOC) and electroluminescence – injection current measurement (EL-J) to disentangle recombination mechanisms in OPV and perovskite cells, respectively. First, I identify the present of Shockley-Read-Hall recombination and surface recombination in OPV devices. I intentionally control the sample geometry to modulate the amount of surface recombination and demonstrate that surface recombination can significantly affect the device performance. In the following chapter, I analyse time dependent suns-VOC and EL-J measurements on perovskite cells with different architectures and pre-conditioning regimes used. I identify the changes in recombination mechanisms with delay time and pre-conditions. The effects of ion migration are used to interpret the results. In the final chapter, I apply luminescence spectroscopy techniques to investigate the degree of fullerene crystallinity in polymer:fullerene blends. Charge-transfer state emission is used to probe the onset of the crystallisation of fullerenes in an amorphous polymer. I relate the CT peak shift directly to the change in microstructure of a blend film.
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Jiang, Yuanyuan. "Scalable Fabrication of High Efficiency Hybrid Perovskite Solar Cells by Electrospray." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/101052.
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Perovskite solar cells have attracted much attention both in research and industrial domains. An unprecedented progress in development of hybrid perovskite solar cells (HPSCs) has been seen in past few years. The power conversion efficiencies of HPSCs has been improved from 3.8% to 24.2% in less than a decade, rivaling that of silicon solar cells which currently dominate the solar cell market. Hybrid perovskite materials have exceptional opto-electrical properties and can be processed using cost-effective solution-based methods. In contrast, fabrication of silicon solar cells requires high-vacuum, high-temperature, and energy intensive processes. The combination of excellent opto-electrical properties and cost-effective manufacturing makes hybrid perovskite a winning candidate for solar cells.
As power conversion efficiencies of HPSCs improves beyond that of the established solar cell technology and their long-term stability increases, one of the crucial hurdles in the path to commercialization remaining to be adequately addressed is the cost-effective scalable fabrication. Spin-coating is the prevailing method for fabrication of HPSCs in laboratories. However, this technique is limited to small areas and results in excessive material waste. Two types of scalable manufacturing methods have been successfully demonstrated to fabricate HPSCs: (i) meniscus-assisted coating such as doctor-blade coating and slot-die coating; and (ii) dispersed deposition based on the coalescence of individual droplets, such as inkjet printing and spray coating. Electrospray printing belongs to the second category with advantages of high material utilization rate and patterning capability along with the scalability and roll-to-roll compatibility.
In Chapter 3 of this dissertation, electrospray printing process is described for manufacturing of HPSCs in ambient conditions below 150 C. All three functional layers were printed using electrospray printing including perovskite layer, electron transport layer, and hole transport layer. Strategies for successful electrospray printing of HPSCs include formulation of the precursor inks with solvents of low vapor pressures, judicial choice of droplet flight time, and tailoring the wetting property of the substrate to suppress coffee ring effects. Implementation of these strategies leads to pin-hole free, low surface roughness, and uniform perovskite layer, hole transport layer and electron transport layer. The power conversion efficiency of the all electrospray printed device reached up to 15.0%, which is among the highest to date for fully printed HPSCs.
The most efficient HPSCs rely on gold and organic hole-transport materials (HTMs) for achieving high performance. Gold is also chosen for its high stability. Unfortunately, the high price of gold and high-vacuum along with high-temperature processing requirements for gold film is not suitable for the large-scale fabrication of HPSCs. Carbon is a cheap alternative electrode material which is inert to hybrid perovskite layer. Due to the ambipolar transport property of hybrid perovskite, perovskite itself can act as a hole conductor, and the extra hole transport layer can be left out. Carbon films prepared by doctor-blade coating method have been reported as the top electrode in HPSCs. The efficiencies of these devices suffer from the poor interface between the doctor-blade coated carbon and the underlying perovskite layer. In Chapter 4, electrospray printing was applied for the fabrication of carbon films and by optimizing the working distance during electrospray printing, the interface between carbon and the underlying perovskite layer was greatly improved compared to the doctor-blade coated carbon film. The resulting HPSCs based on the electrospray printed carbon electrode achieved higher efficiency than that based on doctor-blade method and remarkably, this performance is close to that of gold based devices.
In Chapter 5, preliminary results are provided on the laser annealing of hybrid perovskite films to further advance their scalable manufacturing. All layers of HPSCs require thermal annealing at temperature over 150 C for about half an hour or longer. The time-consuming conventional thermal annealing complicates the fabrication process and is not suitable for continuous production. High temperature over150 C is also not compatible with flexible substrates such as PET. Laser annealing is a promising method for overcoming these issues. It has several other advantages including compatibility with continuous roll-to-roll printing, minimal influence on non-radiated surrounding area, and rapid processing. Laser annealing can be integrated with the electrospray process to realize the continuous fabrication of hybrid perovskite film. Rapid laser annealing process with optimized power density and scanning pattern is demonstrated here for annealing perovskite films. The resulting hybrid perovskite film is highly-crystalline and pin-hole free, similar to that obtained from conventional thermal annealing.Doctor of Philosophy
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Zellmeier, Matthias. "Characterization of hybrid solar cells prepared from poly-thiophenes and silicon." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17666.
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Das Hauptaugenmerk dieser Arbeit liegt auf der Entwicklung einer Hybridsolarzelle, in der der anorganische Halbleiter Silizium, das organische Polymer und das Kontaktsystem so aufeinander abgestimmt sind, dass ihre Kombination zu einem Bauelement mit hohem Wirkungsgrad führt. Um dieses Ziel zu erreichen wurden verschiedene Maßnahmen ergriffen. Neue Polymermaterialien, abgeleitet von dem prototypischen organischen Halbleiter poly(3-hexylthiophen 2,5 diyl) (P3HT), namentlich poly(3-[3,6-dioxaheptyl]-thiophen) (P3DOT) und poly(3-[2,5,8-trioxanonyl]-thiophen) (P3TOT), wurden umfassend hinsichtlich ihrer Struktur untersucht. Poly thiophen/c-Si hybride Solarzellen, hergestellt aus diesen neuen Polymeren, erreichten Effizienzen bis zu 11 %. Die vollständigen Banddiagramme dieser Poly thiophen/c-Si Hybridgrenzflächen wurden mittels Photoelektronenspektroskopie aufgenommen. Außerdem wurde der Einfluss des Kontaktsystems auf die darunter liegenden Schichten mittels Oberflächenspannungsspektroskopie untersucht. Das Resultat dieser Messungen weißt eine Inversionslage unter der Siliziumoberfläche nach, die sich aufgrund des verwendeten semitransparenten Metallkontaktes formt. Dadurch lassen sich diese Bauteile als MIS Inversionsschicht Solarzelle kategorisieren. Um die Hybridsolarzellen weiter zu verbessern, wurde versucht den semitransparenten Metallkontakt durch Graphen zu ersetzen. Das Graphen wurde durch einen CVD-Prozess gewachsen und erreichte eine laterale Ausdehnung von bis zu 1 cm2. Der Übertrag auf die Solarzelle erfolgte mittels eines Wasser und Zerstörungsfreiem Transferprozess. Trotz dem erfolgreichen Aufbringen des Graphen limitierte ein geringer Füllfaktor aufgrund der geringen Ladungsträgerdichte im Graphen den Wirkungsgrad der Solarzelle. In einem letzten Schritt wurde das Polymer P3HT zum ersten Mal mit polykristallinen Siliziumabsorbern kombiniert. Die invertierte Zellstruktur, die hierbei zu Anwendung kam, erhöhte die Lebensdauer der Solarzelle erheblich.The scope of this thesis was the development of a hybrid solar cell based on silicon in which the inorganic semiconductor, the organic polymer and the contact system are combined in such a manner to result in a photovoltaic device with high power conversion efficiency. To reach this goal several measures were taken. New polymer materials derived from the prototypical organic semiconductor poly(3-hexylthiophene 2,5 diyl) (P3HT), namely poly(3-[3,6-dioxaheptyl]-thiophene) (P3DOT) and poly(3-[2,5,8-trioxanonyl]-thiophene) (P3TOT), were extensively characterized regarding its structural properties. Poly thiophene/c-Si hybrid solar cells fabricated from these new polymers exhibited power conversion efficiencies up to 11 %. The energy level alignment of these poly thiophene/c Si hybrid interfaces was studied using photoelectron spectroscopy. Furthermore, the influence of the contact system on the underlying wafer is investigated with surface photovoltage measurements. The measurements revealed the formation of an inversion layer beneath the silicon surface due to the semitransparent metal contact used in the devices. Therefore, these devices can be classified as MIS inversion layer solar cells. To further improve the hybrid poly thiophene/c-Si solar cells by substituting the semitransparent metal contact, graphene was implemented in the device design as a transparent front contact. The CVD grown graphene sheet had a lateral size of up to 1 cm2 and was applied onto the solar cell using a non-destructive and water-free transfer process. However, despite the successful transfer the power conversion efficiency was restricted by the low fill factor due to a low charge carrier density in the graphene. As a last step, hybrid solar cells in the combination P3HT/polycrystalline silicon absorbers on glass were fabricated for the first time. The inverted device structure used for these solar cells proved beneficial for the lifetime. These devices were stable for up to 3 months.
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Dindault, Chloe. "Development of coevaporated hybrid perovskite thin films for solar cells applications." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX079/document.
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Les pérovskites hybrides célèbrent cette année leurs 10e anniversaire dans le domaine du photovoltaïque. En plus de la progression inégalée des rendements des cellules solaires, les pérovskites ont des propriétés optoélectroniques ajustables et peuvent être fabriquées par des procédés bas coûts, ce qui en fait de sérieuses candidates pour les cellules solaires multijunctions. Le réseau cristallin caractéristique des pérovskites hybrides offre une certaine liberté, supportant l’introduction partielle de cations et d’ions halogénures multiples. L’ajustement de la composition d’un matériau pérovskite se traduit par un ajustement de ces propriétés électroniques dont notamment sa structure de bandes. En adaptant la composition il est possible d’obtenir un matériau pérovskite avec une bande interdite de 1,7 eV qui serait parfaitement adapté pour une cellule tandem à base de Silicium cristallin. Les films minces de pérovskites peuvent être fabriqués par une grande diversité de techniques de dépôt, à partir de précurseurs ‘bon marché’ (CH3NH3I et PbI2 par exemple), par des procédés à basse température. Même si la grande majorité des films de pérovskites sont obtenus par la méthode d’enduction centrifuge, celle-ci ne permet pas l’obtention de films homogènes, sur grandes surfaces et de façon répétable. Etant donné l’enjeu industriel qui attend les pérovskites et l’intérêt croissant pour les structures tandems Silicium/Pérovskite, les méthodes sans solvant semblent plus adaptées. Déjà très largement utilisé dans l’industrie des OLEDs, le procédé de coévaporation thermique semble constituer une solution commercialement viable. Publiée pour la première fois en 2013, la synthèse par coévaporation des pérovskites est pour le moment encore étudiée par peu de groupes, car nécessitant des équipements plus coûteux. La présente thèse vise à mettre en place et développer la technique de coévaporation pour la fabrication de films de pérovskites hybrides pour des applications en cellules solaires.Afin d’évaluer la faisabilité du procédé, nous avons commencé notre travail sur un réacteur de démonstration, ce qui nous a permis d’appréhender la réponse à la sublimation des deux précurseurs. Nous avons très vite identifié le comportement du sel organique CH3NH3I comme étant problématique car difficilement contrôlable (s’évaporant sous forme de « nuage »), comme nous l’avions lu dans la littérature. En six mois d’utilisation de ce réacteur, nous avons fabriqué des films de pérovskites ayant permis d’atteindre des rendements de 9% sur des cellules solaires, malheureusement avec une faible reproductibilité (que nous expliquons en partie par le caractère aléatoire de l’évaporation du composé organique CH3NH3I). Nous nous sommes trouvés dans l’incapacité de comprendre plus en profondeur le procédé à cause d’un manque de fonctionnalités de l’équipement. Grâce à ces différents retours d’expérience nous avons pu concevoir, en étroite collaboration avec l’équipementier, un réacteur semi-industriel dédié à la fabrication de films de perovskites par coévaporation. Suite à sa mise en place, nous nous somme focalisé sur la problématique de la reproductibilité dans nos expériences en essayant de diminuer l’impact du nuage organique. Bien que les efficacités atteintes en cellules solaires pour des films coévaporés fussent moindres que pour des films déposés par la technique classique d’enduction centrifuge, nous soupçonnions néanmoins une meilleure homogénéité des films obtenus par voie sèche. Nous avons ainsi intégré à cette thèse une étude comparative voie liquide/voie sèche par le biais d’une technique de spectromicroscopie rayons X en SynchrotronHybrid perovskites celebrate this year their 10-year anniversary in the photovoltaic field. Besides the unprecedented rise in solar cells efficiencies, perovskite materials have tunable optical properties and can be manufactured at low cost, making them very promising candidates for the high efficiency, multijunction solar cells strategy. Perovskite crystal structure offers a relative degree of freedom, allowing the partial integration of multiple cations and halide ions. This chemical composition tuning translates into a bandgap tuning. Through fine chemical engineering, the 1.7 eV requirement for a c-Si-based tandem device can be achieved. Perovskite thin films can be prepared by a large variety of deposition techniques, from low cost precursors (CH3NH3I and PbI2 for instance), through low-temperature processes. While most of the reported works on perovskite thin films are based on the basic wet-process spincoating technique, this latter hardly allows large scale, homogeneous and reproducible deposition. With the future challenge of industrialization and the increasing interest for the Silicon/Perovskite tandem approach, solvent-free methods appear more suitable. Already widely implemented in the OLED industry, coevaporation stands as a viable option for perovskites’ future. Reported for the first time in 2013, coevaporated perovskites are still scarcely studied compared to wet-based techniques, requiring more expensive set ups. In the present thesis, we implemented and developed the coevaporation process to fabricate perovskite thin films for solar cells applications.Starting off on a proof-of-concept reactor to assess the feasibility of the technique, we got accustomed to the perovskite precursors behaviour and identify very early on the organic precursor to be hardly manageable, as reported in the literature. In six months, we were nonetheless able to obtain nice perovskite films leading to 9% efficient photovoltaic devices, unfortunately with a poor reproducibility that we think to be partially due to the cloud vapour behaviour of CH3NH3I. We eventually found ourselves missing some features on the equipment, preventing us from accurately get a grasp on the process. From this feedback we then designed, hand in hand with the manufacturer, a dedicated semi-industrial equipment for perovskite coevaporation. Following its implementation, we then focused on establishing the reproducibility of the method, trying to mitigate the parasitic effect of the organic compound. Even though the efficiencies in solar cells were still slightly lower for coevaporated perovskites, with respect to classical spincoated ones, we expected the material homogeneity to be in favour of the vacuum-based process. We then eventually integrated to this thesis a comparative study between wet- and dry-processed perovskite films using a Synchrotron-based X-ray spectromicroscopy technique
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DEGANI, MATTEO. "Design and Characterization of Hybrid Perovskite for New Generation Solar Cells." Doctoral thesis, Università degli studi di Pavia, 2023. https://hdl.handle.net/11571/1471734.
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Le perovskiti sono semiconduttori con caratteristiche optoelettroniche ideali per l’applicazione fotovoltaica (elevato assorbimento, alta mobilità di carica) e con un basso costo. Tuttavia, la loro applicazione commerciale è limitata dall’instabilità di questo materiale. Il degrado della perovskite è causato da alcuni fattori esterni come ossigeno e umidità.
In questa tesi sono state studiate entrambe le strutture (NIP e PIN) delle celle solari a perovskite. Per renderle più stabili ed efficienti sono state trattate con nuovi metodi di passivazione e con materiali di recente sintesi che hanno portato al raggiungimento dell’obiettivo. Sono state anche usate diverse tecniche di caratterizzazione per comprendere le ragioni dei miglioramenti nelle prestazioni di questi dispostivi. Questo ha permesso di ottenere una maggiore conoscenza dei meccanismi dei miglioramenti e di conseguenza a una più vicina commercializzazione di questo materiale.Perovskites are semiconductors with ideal optoelectronic properties (like high absorption and high charge mobility) for photovoltaic applications and at a low cost. However, their commercial application is limited by the instability of this material. The degradation of perovskite is caused by some external factors such as oxygen and humidity. In this thesis both structures (NIP and PIN) of perovskite solar cells have been studied. To make them more stable and efficient, they have been treated with new passivation methods and with recently synthesized materials that have led to the achievement of the goal. Various characterization techniques were also used to understand the reasons for the performance improvements of these devices. This allowed obtaining a greater knowledge of the mechanisms of the improvements and consequently to closer commercialization of these perovskites.
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CIAMMARUCHI, LAURA. "Studies on stability and degradation of hybrid and organic solar cells." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2013. http://hdl.handle.net/2108/203513.
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Yang, Hong-wei, and 楊鴻偉. "Flexible heterostructure organic solar cells." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/52789680157688338732.
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碩士國立成功大學
光電科學與工程研究所
97
The characteristics of pentacene/perylene derivatives based flexible organic solar cells (FOSCs), in which the pentacene and N,N′-diheptyl-3,4,9,10-tetracarboxylic diimide (PTCDI-C7H15) are donor and acceptor layers, respectively, are discussed in this thesis. The open circuit voltage (VOC) is given by the difference between the highest occupied molecular orbital of the donor molecules and the lowest unoccupied molecular orbital of the acceptor molecules. In this study, an obvious shift of the VOC was observed when the flexible substrate was under compressive bending or tensile bending. Photoluminescence (PL) and ultraviolet-Visible spectrophotometer were performed on the FOSC to investigate the correlations between VOC of the FOSC and energy gaps of the donor and acceptor for explaining the phenomenon of the shift of the VOC. Moreover, we applied micro Raman spectroscopy to study the degree of the strain for the pentacene film through the full width at half-maximum (FWHM) of Raman peak at various bending curvatures. Finally, the red shift of the energy gap of PTCDI-C7H15 was due to the compressive strain on PTCDI-C7H15 molecules was also confirmed by temperature dependent PL in which the compressive strain is induced by thermal effect.
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Chen, Chiang-Ting, and 陳建廷. "Inorganic/organic hybrid solar cells." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/82622061600534626215.
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碩士臺灣大學
物理研究所
98
At the time of energy crisis, it is urgent to find proper renewable energy. Among all the possibilities, solar cells are the most noticeable. There are many kinds of solar cells. Of all these solar cells, the crystalline based solar cells have the highest efficiency. But its production process is quite costly, lacking economical benefits. In contrast, organic solar cells have a great advantage of low cost. It only needs a spin coater to fabricate the active layer and then annealed with a hotplate. With its low cost and thin thickness, it would be practical to use them on plastic board to make flexible solar cells. This thesis is mainly focused on the research of inorganic/organic hybrid solar cells. The inorganic/organic hybrid solar cells are made from ZnO rods and polymer P3HT/PCBM. After cleaning the ITO glass, ZnO rods were fabricated by the hydrothermal method, and then P3HT/PCBM was spin coated on ZnO nanorods. Finally, Ag contact was evaporated for the measurement of photocurrent. We discover that a thin layer deposited by spin coated C60 solution before the fabrication of P3HT/PCBM layer can greatly improve the performance of solar cells. The main reasons for the increased efficiency of solar cells can be attributed to the enhanced exciton separation as well as the reduction of defect states. As a result, charges can transfer from polymer blend to ZnO-nanorod more effectively and subsequently travel to electrodes leading to the improved performance in the photovoltaic devices.
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Chen, Po-Han, and 陳柏翰. "Organic/Inorganic Hybrid Tandem Solar Cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/94021974960646421800.
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碩士國立交通大學
光電工程研究所
102
We propose a series-connected hybrid tandem solar cell which consists of an organic solar cell (P3HT/PC60BM) as the top cell and an organic/crystalline silicon hybrid solar cell (PEDOT:PSS/c-Si nanowires) as the bottom cell. Based on the device structure, the organic materials can be directly spun-cast onto the inorganic silicon substrate with thermally evaporated metal contacts, making solution-based processes possible for rapid and low-cost production. With a proper design, the hybrid tandem device architecture can achieve a high open-circuit voltage (VOC) and power conversion efficiency (PCE), offering a promising approach for next-generation, low-cost and high-efficiency photovoltaics. We established a device simulation model to investigate the photovoltaic characteristics of the proposed hybrid tandem solar cells by combining the organic and silicon-based hybrid solar cells with a hypothetic recombination layer. First, the model of single junction solar cells is fitted to the current-voltage curve of fabricated devices. Next, we investigate the properties of the recombination layer between the sub-cells and observe strong correlations with the photovoltaic performance of tandem cells. In our preliminary model, we have realized a tandem cell with an open-circuit voltage (VOC), short-circuit current (JSC), fill-factor (FF) and power conversion efficiency (PCE) of 0.949 (V), 6.794 (mA/cm2), 57.743 % and 3.724 %, respectively. We also designed the structures and processes for the sub-cells and hybrid tandem solar cells fabrication. The intermediate layer between the sub-cells strongly affects the photovoltaic performance of the tandem cells and can be presented with evaporation or solution process. Currently, the characteristics of real hybrid tandem solar cells remain significantly lower than the simulation results. For evaporation process, we obtained the tandem cell with an open-circuit voltage (VOC), short-circuit current (JSC), fill-factor (FF) and power conversion efficiency (PCE) of 0.745 (V), 3.895 (mA/cm2), 40.561 % and 1.177 %, respectively. For solution process, we obtained the tandem cell with an open-circuit voltage (VOC), short-circuit current (JSC), fill-factor (FF) and power conversion efficiency (PCE) of 0.772 (V), 3.132 (mA/cm2), 23.957 % and 0.58 %, respectively. A number of challenging issues, including interface physics、recombination layer and device design will be discussed in this thesis.
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Chang, Shun-Fa, and 張舜發. "Organic/Inorganic Hybrid Heterojunction Solar Cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/06616821514340569736.
Full textAbstract:
碩士國立交通大學
應用化學系分子科學碩博士班
102
Over the past few years, hybrid devices based on conjugated polymer/silicon heterojunction structures .In this paper, hybrid solar cell based on poly(3,4-ethylene- dioxythiophene):polystyrenesulfonate (PEDOT:PSS) directly spin-coating on n-type silicon wafer and n-type GaAs wafer. In the first part, a hybrid PEDOT:PSS/silicon heterojunction solar employed several n-type silicon substrate with different quality and thickness .Compared to the planar PEDOT:PSS/silicon cells,the maximal power conversion efficiency under AM 1.5 global one sun illumination is 9.76%. In the second part,A typical III–V solar cell requires a thickness of several micrometers to absorb all of the incoming photons. We present 3000-nm-thick GaAs absorbing layer based on heavily-doping GaAs grown by Molecular beam epitaxy ,coated with PEDOT:PSS. The highest power conversion efficiency under AM 1.5 global one sun illumination is 9.874%.
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"Optimization of Monocrystalline MgxCd1-xTe/MgyCd1-yTe Double-Heterostructure Solar Cells." Doctoral diss., 2017. http://hdl.handle.net/2286/R.I.44213.
Full textAbstract:
abstract: Polycrystalline CdS/CdTe solar cells continue to dominate the thin-film photovoltaics industry with an achieved record efficiency of over 22% demonstrated by First Solar, yet monocrystalline CdTe devices have received considerably less attention over the years. Monocrystalline CdTe double-heterostructure solar cells show great promise with respect to addressing the problem of low Voc with the passing of the 1 V benchmark. Rapid progress has been made in driving the efficiency in these devices ever closer to the record presently held by polycrystalline thin-films. This achievement is primarily due to the utilization of a remote p-n heterojunction in which the heavily doped contact materials, which are so problematic in terms of increasing non-radiative recombination inside the absorber, are moved outside of the CdTe double heterostructure with two MgyCd1-yTe barrier layers to provide confinement and passivation at the CdTe surfaces. Using this design, the pursuit and demonstration of efficiencies beyond 20% in CdTe solar cells is reported through the study and optimization of the structure barriers, contacts layers, and optical design. Further development of a wider bandgap MgxCd1-xTe solar cell based on the same design is included with the intention of applying this knowledge to the development of a tandem solar cell constructed on a silicon subcell. The exploration of different hole-contact materials—ZnTe, CuZnS, and a-Si:H—and their optimization is presented throughout the work. Devices utilizing a-Si:H hole contacts exhibit open-circuit voltages of up to 1.11 V, a maximum total-area efficiency of 18.5% measured under AM1.5G, and an active-area efficiency of 20.3% for CdTe absorber based devices. The achievement of voltages beyond 1.1V while still maintaining relatively high fill factors with no rollover, either before or after open-circuit, is a promising indicator that this approach can result in devices surpassing the 22% record set by polycrystalline designs. MgxCd1-xTe absorber based devices have been demonstrated with open-circuit voltages of up to 1.176 V and a maximum active-area efficiency of 11.2%. A discussion of the various loss mechanisms present within these devices, both optical and electrical, concludes with the presentation of a series of potential design changes meant to address these issues.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2017
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Cheng, Chieh-wen, and 鄭傑文. "Wafer-bonded PEDOT:PSS/GaAs thin-film hybrid solar cells and Wafer-scale PEDOT:PSS/Si hybrid solar cells." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/90953425913119300561.
Full textAbstract:
碩士國立交通大學
應用化學系碩博士班
104
In recent years, development of hybrid solar cells which combines the advantages from inorganic materials and organic solar cells provides a simple, low temperature process to fabricate solar cell devices with reduced cost. Content of this thesis work was divided into two parts. In the first part, we demonstrated a PEDOT:PSS on GaAs thin film hybrid solar cells by using wafer bonding and chemical wet etching techniques. The thin film hybrid solar cells reached an excellent power conversion efficiency efficiency of 8.93% when an additional p+ Al0.3Ga0.7As epi-layer is deposited on the surface of the solar cells to provide a front-surface field. However, we uncovered that the bonding materials was able to diffuse into the GaAs thin film during the wafer-bonding stage, which led to the decrease in efficiency. In the second part of the thesis, we demonstrated an 4 inch PEDOT:PSS/silicon hybrid solar cell device by adding the DuPont Capstone FS-31 surfactant into the spin-coated PEDOT:PSS layer. Effects of the non-uniformity of the PEDOT:PSS layer on cell performance was investigated. The device achieved an overall conversion efficiency of 10.25% and a total output current and voltage of 26.23 mA/cm2 and 0.46 V, respectively. The as-made large-area solar cells benefits from the reduction in the fabrication time and cost, and particularly in preventing the pollution from the wafer-cutting.
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Lin, Hung-Chou, and 林宏洲. "The Study of Utilizing Surface Periodic Structure on Silicon Heterostructure Solar Cells." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/24893819222580565811.
Full textAbstract:
碩士國立臺灣大學
電子工程學研究所
102
Cause the energy crisis, the solar photovoltaics(PV) technologies and conversion efficiency have been improved. The PV market is growing ever more noticeable year by year. Every kind of the solar cell are published on Journal or letters. However, crystalline silicon(c-Si)-base solar cell has a lots benefits that is like low cost, high yield quality and mass production. Silicon is the second abundant element on earth. The energy gap for silicon is very suitable to absorb energy in solar spectrum. Next decades, crystalline silicon (c-Si)-base solar cell still is the mainstream in the market. In order to increasing the PV power generation,efficient light trapping has become an important area of research. This study focus on the short current density of the 1D gratings with different period and depth on the heterojuction with intrinsic thin-layer(HIT) solar cell wafer. We use the E-beam lithography to identify the exposure region and use Reactive Ion Etch to fabricate the 1D grating. We confirm the light width and depth by Atomic force microscope and Focus Ion beam. After fabricated process, We measure the IV curve and external quantum efficiency. We find the best 1D grating period is 800nm. And the result shows that the period 800nm grating structure can promote the absorption in wavelength of 0.7-1.1μm. Compare with the flat solar cell, period 800nm grating s increase 14% current density.In addition, we change the arrangement like chessboard lattice and measure the IV curve. We find that the chessboard lattice could be enhanced 17%. By Rsoft CAD-Layout Simulation, we simulate the different period gratings total reflection and inner electric field plot.After simulation, we compare the experiment and the simulation, and so that find that the simulation result almost fit in with experiment data.
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"The Design and Demonstration of Monocrystalline CdTe/MgCdTe Double-Heterostructure Solar Cells." Doctoral diss., 2016. http://hdl.handle.net/2286/R.I.41252.
Full textAbstract:
abstract: Cadmium Telluride (CdTe) possesses preferable optical properties for photovoltaic (PV) applications: a near optimum bandgap of 1.5 eV, and a high absorption coefficient of over 15,000 cm-1 at the band edge. The detailed-balance limiting efficiency is 32.1% with an open-circuit voltage (Voc) of 1.23 V under the AM1.5G spectrum. The record polycrystalline CdTe thin-film cell efficiency has reached 22.1%, with excellent short-circuit current densities (Jsc) and fill-factors (FF). However, the Voc (~900 mV) is still far below the theoretical value, due to the large non-radiative recombination in the polycrystalline CdTe absorber, and the low-level p-type doping.
Monocrystalline CdTe/MgCdTe double-heterostructures (DHs) grown on lattice-matched InSb substrates have demonstrated impressively long carrier lifetimes in both unintentionally doped and Indium-doped n-type CdTe samples. The non-radiative recombination inside of, and at the interfaces of the CdTe absorbers in CdTe/MgCdTe DH samples has been significantly reduced due to the use of lattice-matched InSb substrates, and the excellent passivation provided by the MgCdTe barrier layers. The external luminescent quantum efficiency (η_ext) of n-type CdTe/MgCdTe DHs is up to 3.1%, observed from a 1-µm-thick CdTe/MgCdTe DH doped at 1017 cm-3. The 3.1% η_ext corresponds to an internal luminescent quantum efficiency (η_int) of 91%. Such a high η_ext gives an implied Voc, or quasi-Fermi-level splitting, of 1.13 V.
To obtain actual Voc, the quasi-Fermi-level splitting should be extracted to outside the circuit using a hole-selective contact layer. However, CdTe is difficult to be doped p-type, making it challenging to make efficient PN junction CdTe solar cells. With the use of MgCdTe barrier layers, the hole-contact layer can be defective without affecting the voltage. P-type hydrogenated amorphous silicon is an effective hole-selective contact for CdTe solar cells, enabling monocrystalline CdTe/MgCdTe DH solar cells to achieve Voc over 1.1 V, and a maximum active area efficiency of 18.8% (Jsc = 23.3 mA/cm2, Voc = 1.114 V, and FF = 72.3%). The knowledge gained through making the record-efficiency monocrystalline CdTe cell, particularly the n-type doping and the double-heterostructure design, may be transferable to polycrystalline CdTe thin-film cells and improve their competitiveness in the PV industry.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2016
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Pan, Huai-Te, and 潘懷德. "Gallium arsenide based heterojunction hybrid solar cells." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/17576530971613296864.
Full textAbstract:
碩士國立交通大學
光電工程研究所
102
The price of crude oil climbs progressively, which winds the horn of energy crisis. Photovoltaics have been one of the critical roles in various green energies. In order to reduce raw material and fabrication cost, hybrid solar cells combining organic conductive polymers and inorganic semiconductors have become rising topic in recent years. Due to the properties of direct energy gap and high electron mobility, GaAs has high absorption coefficient in visible wavelengths and good carrier transport characteristics. In this work, we substitute GaAs for Si to fabricate organic/inorganic hybrid devices. According to the analysis of one-dimensional simulation, at the same surface and bulk defect level, the open-circuit voltage of GaAs-based cell is larger, but the short-circuit current density is lower because of proper band alignment and larger bandgap resulting in shorter cut-off wavelength of absorption spectrum respectively. It is expected that the cell performance would exceed Si-based one. In conventional solar cell design, base doping should be lower in order that the width of depletion region on base side would lengthen, which is beneficial for carrier collection. Generally, doping concentration of GaAs wafer is hard to be manufactured below 1017cm-3, therefore we grow buffer layer and low-doped(1016cm-3) absorber by MOCVD. All electrical properties are enhanced, and average efficiency achieves 6.6%, which is 203% of the one without these epilayers. The pattern of top contact is composed of one bar and several grids connected together, so the shading ratio is a significant parameter that dominates the amount of incident light and the condition of carrier transport. Optimized planar devices with shading ratio around 14% (60μm width of grid) can reach a high efficiency of 7.66%. In addition, we perform simulations for planar devices to analyze the internal electrical properties. For further cell performance improvement, we etch nanostructure on front surface to reduce reflectance and increase light absorption. Preferring anisotropic etching and precise morphology control, we choose dry etching method. By use of self-assembly polystyrene nanosphere lithography technique, monolayer of nanospheres is deposited on substrate, followed by two stages of reactive ion etching. First step is to shrink spheres, reserving the spacing among nanorods and controlling the upper part morphology of nanorods. Second step is GaAs etching, dominating the length of nanorods. Although damage removal etching is performed, residual defects and enlarged surface area slightly lower the Voc. However, compared to planar devices, the average Jsc enhances 33%, leading to the highest efficiency of 7.74%.
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Lee, Yi-Hsuan, and 李宜璇. "Fabrication and characteristics of IZO/Cu2O heterostructure solar cells prepared by thermal oxidation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/fft6qf.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
99
In this dissertation, cuprous oxide(Cu2O) films were prepared by thermal oxidation using the Cu films were prepared by RF reactive magnetron sputtering, and changing the temperature and time of annealing to obtain the different performances of Cu2O thin films, After that, deposition of indium zinc oxide (IZO) by RF reactive magnetron sputtering on the Cu2O films to fabricated IZO/Cu2O heterostructure solar cells. For the analyses of thin films, elements,composition and surface structure of p-Cu2O and n-IZO thin films were characterized by SEM and XRD measurements. Mobility,carrier concentrations and resistances of p-Cu2O and n-IZO thin films were measured by and Hall measurement. For the analysis of solar cells,use In to be the metal electrode for I-V measurement. Performance of IZO/Cu2O heterostructure solar cells were compared. The best results were Voc = 0.05 V、Isc = 0.00705 mA/cm2、FF = 0.447 and η = 0.00158 % for the solar cell with 1.1 μm p-Cu2O by thermal oxidation on 500℃ in 10 minutes.
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Tonui, Joel Kipkorir. "Hybrid photovoltaic/thermal solar energy systems." Thesis, 2006. http://nemertes.lis.upatras.gr/jspui/handle/10889/3894.
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林建志. "Studies on inorganic-organic hybrid based solar cells." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/12438524384947146192.
Full textAbstract:
碩士國立臺北科技大學
化學工程系碩士班
91
Solar light is the most important source of safe and regenerative energy because it is the only inexhaustible energy source. The main purpose of this paper describes as follows: First, inorganic nanoparticles (TiO2) and organic conducting polymer (MEH-PPV) was synthesized and manufactured the double layers solar cells. Second, the dye molecule (mercurochrome) was added to fabricate as an all solid-state dye-sensitized solar cells (DSSCs). The characteristic I-V curve of these solar cells will be discussed. The TiO2 nanoparticles was synthesized by sol-gel method method. SEM and TEM could decide the size of nanoparicles. The morphology of nanoparticles on the substrate could be observed by AFM. The crystal structure of TiO2 particles could be analyzed by XRD. According to the characteristic peak of XRD, we can calculate the size with Scherrer equation. NMR and FT-IR will be characterized the structure of MEH-PPV. The Mw and PDI of MEH-PPV were decided by GPC. The maximum absorption peak of MEH-PPV was measured by UV-Vis spectra and could be calculated the energy gap via the equation.
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Yang, Po-Fan, and 楊博帆. "Photophysical and physical properties of hybrid solar cells." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/hqw483.
Full textAbstract:
碩士國立清華大學
材料科學工程學系
102
In this thesis, we focus on the photophysical and physical properties of hybrid solar cells, including dye-sensitized solar cells (DSSCs), Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)/Si organic/inorganic hybrid solar cells and novel perovskite solar cells. We utilized a series of measurement systems to analyze the charge recombination process and carrier concentration in DSSCs and organic/inorganic hybrid solar cells. We investigated the detailed physical properties of perovskite thin films deposited on different under-layer materials. The relationship between surface morphology of perovskite thin films and the device power conversion efficiencies is also discussed. In the first chapter, we briefly review the history of photovoltaics, especially recent development of hybrid solar cells. In the second chapter, the operation mechanisms and photovoltaic characteristics of the hybrid solar cells are described in detail. The measurement setups and principles of current-voltage curve, external quantum efficiency analysis, and transient photovoltage/photocurrent measurements are also shown in this chapter. In the third chapter, the photophysical measurement systems were employed to analyze the Ruthenium(II)-based, Osmium(II)-based and metal-free organic sensitizers in DSSCs. We find that the addition of spacial barrier in molecular structures can slow down the charge recombination from TiO2 to the electrolyte and enhance photovoltage. Besides, dye loading also affects the charge recombination. These two factors need to be considered in the future molecular design of high efficiency dye sensitizer. In the fourth chapter, the transient photovoltage/photocurrent measurements were utilized to investigate the influence of trap-state density on power conversion efficiency of PEDOT:PSS/Si organic/inorganic hybrid solar cells. We find that the SiOx passivation layer decreases the amount of trap-state density. However, thicker SiOx becomes a barrier for carrier transportation due to its non-conducting property. In the fifth chapter, we manufactured perovskite solar cells from the home-made precursor reactant CH3NH3I. We used planar ZnO thin films as an electron transporting under-layer layers. Poor efficiency was found in solution casted devices with the ZnO under-layer due to the non-uniform surface morphology of perovskite thin films. The surface morphology and surface coverage can be largely improved by vacuum evaporation of perovskite thin films on MoO3, TiO2, and PEDOT:PSS under-layers. We believe that efficient perovskite hybrid solar cells can be realized by utilizing these perovskite/under-layer pairs.
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Huang, Tse-Kai, and 黃則凱. "Hybrid P3HT/TiO2 Nanorods Bulk Heterojunction Solar Cells." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/52034833220423155708.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
95
The investigations focus on hybrid materials photovoltaic properties of organic conjugated polymer and inorganic nano-semiconductor. First of all, we discuss how TiO2 nanorods support charge separation and charge transport in TiO2/P3HT hybrid solar cells. Therefore we tune the TiO2 doping concentration to optimize devices performance. Secondly, we focus on the topic of thermal treatment effect on devices performance. It is observed that devices performance could significantly enhance after high temperature annealing. Based on optical properties, XRD, and Time-of-Flight carrier mobility measurement system, we discover that after annealing both the crystallite size and carrier mobility increasing. Finally, we use synthesis method to change the length of TiO2 nanorods and investigate the length dependent effect on devices performance. We know that TiO2 inclusion supports both charge separation and transport, therefore we focus on different length of TiO2 nanorods effect on charge separation and transport properties. At the same doping concentration, the shorter TiO2 nanorods result in more surface area and contribute to more efficient charge separation; the otherwise the longer TiO2 nanorods could easily form continuous transport path to support efficient charge transport. Based on the balance of these two effects, we try to find the maximal performance of TiO2/P3HT hybrid solar cells.
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Huang, Bo-Yu, and 黃柏瑜. "High Efficiency Organic/Inorganic Hybrid Heterojunction Solar Cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/00283989633257040581.
Full textAbstract:
碩士國立交通大學
光電工程學系
100
An organic/inorganic hybrid solar cells are cheap alternatives to conventional silicon-based solar cells. The devices take the advantages of high optical absorption and carrier mobility of inorganic semiconductors, while maintaining the easy processing attributes of polymers or other soft materials. However, the conduction of holes has been a major technical barrier for the advance of such novel devices. In this study, a hybrid PEDOT:PSS/silicon heterojunction solar cell is demonstrated with an average power conversion efficiency of 9.84% using rapid solution-based organic processes. Then we propose the use of silver nanowires (AgNWs) to improve the series resistance of the hybrid solar cells and further to realize solution-processed silicon-based photovoltaics. At last, the modeling of such devices predicts an efficiency exceeding 20% with improved reflection loss and material properties, shedding light into the attainment of high-efficiency and low-cost photovoltaics based on organic/inorganic hybrid devices. In the first section of my thesis, we discuss how to fabricate hybrid heterojunction solar cells with silicon nanowire and pyramidal surface textures. The hybrid heterojunction solar cells are demonstrated based on the composite of conductive polymer PEDOT:PSS directly spun-cast on a micro-textured n-type crystalline silicon wafer. Moreover, the industrial-standard microscale surface textures improve the antireflection and carrier collection without increasing much surface recombination. Then we replace the frontal metal contacts with the coating of AgNWs. The cross-linked AgNWs offer high transparency and low sheet resistance, which can be easily fabricated using low-cost and non-toxic materials. In the second section, we employed a self-consistent drift-diffusion and Poisson solver to theoretically investigate the effects of interface/bulk defects, doping concentration, and back surface recombination on the device performance. With a proper choice of band alignment, the modeling of such devices predicts an efficiency exceeding 20% with improved reflection loss and material properties.
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Su, Chun-Hsing, and 蘇峻興. "Fabrication and Characterization of Nanostructure Hybrid Solar Cells." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/01398068579599457796.
Full textAbstract:
碩士國立成功大學
航空太空工程學系碩博士班
97
The objective of this study is to fabricate ordered nanostructure organic solar cells by using thermal nanoimprinting technique. By using the technique, we are able to appropriately control the donor-accepter interfacial morphology. When the light is absorbed by the active layer of the organic semiconductor, a bounded electron-hole pairs can be generated, which is so called exciton. Because of the LUMO difference between the donor and acceptor, the excitons will separate when they diffuse across the donor-acceptor interface. We create a smooth, direct pathway to make sure that the excitons will reach the interface and then separate. This straight pathway let the charge carries transport to the electrode more effectively. We develop a new method of making silicon molds. It provides a low cost, highly efficient way to fabricate nanoimprinting molds. Because the thermal nanoimprinting condition is carefully monitored, there comes a significant improvement in the short-circuit current, fill factor, and the power efficiency. The current density rises from 0.15 to 1.08 mA/cm2, fill factor increases from the lowest level 0.25 to the highest 0.55.
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Lin, Yun-Yue, and 林雲躍. "Solution Processible Polymer/Inorganic Nanomaterials Hybrid Solar Cells." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/48879764143109742347.
Full textAbstract:
博士國立臺灣大學
材料科學與工程學研究所
97
This thesis aims to explore an alternative for silicon based solar cell. The hybrid materials, which are a combination of conjugated polymer and inorganic nanomaterial, provide numerous promising device properties such as effective carrier transport, strong light absorption and flexibility. Compared with conventional silicon based solar cell, this hybrid material can provide a low cost, environmental friendly, light weight and easy to process possibility. Though the performance of polymer based solar cell is still too low for large scale application, it is still possible to increase device conversion efficiency by improving carrier transport and extending light harvesting range. In chapter 3, we focus on studying organic-inorganic hybrid bulk heterojunction solar cell based on conjugated polymer P3HT and TiO2 nanocrystal. Our result show the optimal device performance can be achieved by introducing 50 weight percent TiO2 nanorod into P3HT matrix. By TiO2 surface modification, the optimal device performance has a power conversion efficiency of 2.2%. Compared with CdSe/conjugated polymer hybrid, this material system not only provides comparable device efficiency, but also develops a nontoxic, environmental friendly solar cell. In Chapter 4, we demonstrate enhanced the performance of polymer solar cell based on poly(3-hexylthiophene)(P3HT)/ZnO nanorods array heterojunction hybrid. By infiltrating P3HT polymer chain along ZnO nanorods array nanostructure, carrier mobility has been found a increase from 8.2×10-5 cm2/Vs to 7.7×10-4 cm2/Vs, companied with polymer chain were aligned perpendicularly to substrate surface. The optical anisotropic measurement revealed that chain orientation of P3HT prefers align along ZnO (l0Ī0) surface. Our experiments also showed that device performance can be further improved by surface modified ZnO nanorod surface. A novel approach to improve polymer solar cell using electric field assisting process was proposed in chapter 5. Our results showed better device performance can be achieved by carefully applied electric field during thin film process. Atomic force microscopy measurement showed higher polymer chain organization properties of blend film. By changing the natural orientation of polymer order, the electrical properties, including device performance, carrier mobility in vertical direction can both be enhanced. The optical anisotropic measurement also showed the optical anisotropic ratio is as a function of the magnitude of electric field. A solution process single wall carbon nanotube (SWCNT) thin film as a transparent electrode for organic solar cell application was studied in chapter 6. By chemical modified SWCNT thin films using nitric acid and thionyl chloride treatments, a significant decrease of sheet resistance can be achieved. Photovoltaic devices based on P3HT and PCBM fabricated on surface functionalized SWCNT electrode shows a promising device conversion efficiency of 1.87% can be performed. The variation of open circuit voltage (Voc) in P3HT and PCBM bulk heterojunction organic photovoltaic with functionalized transparent SWCNT networks indicated that the change of surface potential of SWCNT thin films resulted in correlated change in short circuit current density and open circuit voltage of the photovoltaic devices. In previous chapters, we have proposed several approaches to improve device performance. In chapter 7, we use new material for organic IR harvesting solar cells application based on P3HT/FeS2 blend. The devices exhibited high photo-electric current conversion efficiency in infrared region (>700 nm).where the external quantum efficiency was 6.5% at wavelength 650nm and 1% at 700 nm. The photoresponsed measurement also indicated that onset of photogenerated edge was about 900nm, which is contributed by FeS2 NCs. These results also pointed out that FeS2 NCs: P3HT hybrid can provide a low cost, environment friendly and easy process organic solar cell. Finally, polymer solar cells that have been constructed by hybrid materials are very promising. This thesis mainly studied polymer solar cells and has provided some approaches to improve device performance. Our findings showed carrier transport properties and excitons dynamics are both directly influenced by photoactive layer morphology. In the future, we believe device performance can be further improve by optimized morphology of polymer based heterojunction solar cell with a good percolation of both phases to the respective electrode.
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Chang, Chih-Wei, and 張志維. "Silicon solar cells with homo/heterojunction hybrid structures." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/97054749510679951137.
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碩士國立高雄應用科技大學
光電與通訊工程研究所
101
In this paper, HHHS (Homo-heterojunction hybrid structure) solar cells have better efficiencies than Sanyo HIT (Heterojunction with intrinsic thin layer) solar cells by AFORS-HET numerical simulation software. The hybrid heterogeneous structure is based on single-crystal silicon with two lateral depositions of amorphous silicon. The structure not only avoids patent issues of Sanyo HIT but also dispenses with the troubled production of amorphous silicon intrinsic layer with high purity. The conversion efficiency of 19.48% of HHHS solar cells is higher than that of 19.44% of HIT solar cells. There are two main reasons for HHHS’s outperformance to HIT. First, HHHS operates a better internal quantum efficiency in short wavelength interval than HIT does. Second, the tunneling barrier of HHHS is thinner than that of HIT; therefore, it is easier to reach the P electrode of HHHS compared to HIT. In view of the slope of the conversion efficiency to the thickness of the first middle layer, the slope of HHHS is smaller than HIT, so HHHS has a higher process tolerance during fabricating critical layers. Consequently, HHHS provides a better choice for silicon heterojunction solar cells than HIT which is well-known for a long time.