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Ehrler, Bruno. "Nanocrystalline solar cells." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607785.
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Musselman, Kevin Philip Duncan. "Nanostructured solar cells." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609003.
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Subbaiyan, Navaneetha Krishnan. "Supramolecular Solar Cells." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc149672/.
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Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-p and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.
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Stenberg, Jonas. "Perovskite solar cells." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-137302.
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Perovskite solar cells (PSC) performance has risen rapidly the last few years with the current record having power conversion efficiency (PCE) of 22.1 %. This has attracted a lot of attention towards this alternative solar cell that can be manufactured with less energy and toxic material than traditional silicon solar cells. The purpose of this thesis is to reproduce high performance PSC from known recipe by Zhang et al. with potential of PCE reaching above 18 %. The thesis covers the theory regarding how a PSC operates, how they are measured and which parameters are important for a high performance PSC. The thesis includes a detailed manuscript on how to manufacture high performance PSC layer by layer and how to characterize the performance of the cells by IV-measurements. Furthermore, it includes scanning electron microscopy (SEM), by which the cells surface layers and cross-section could be evaluated. The result shows that it is possible to reproduce the PSC from literature and achieve a PCE of 18.8 %. However, the cells PCE decrease by 15 % during 2 hours of constant illumination, due to lack of stability. The manufactured PSC was used to power two catalysts that splits water into O2 and H2 and managed to reach a solar to hydrogen conversion efficiency (STHCE) of 13 %.
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Bett, Alexander Jürgen [Verfasser], and Stefan [Akademischer Betreuer] Glunz. "Perovskite silicon tandem solar cells : : two-terminal perovskite silicon tandem solar cells using optimized n-i-p perovskite solar cells." Freiburg : Universität, 2020. http://d-nb.info/1214179703/34.
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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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Søiland, Anne Karin. "Silicon for Solar Cells." Doctoral thesis, Norwegian University of Science and Technology, Department of Materials Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-565.
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This thesis work consists of two parts, each with a different motivation. Part II is the main part and was partly conducted in industry, at ScanWafer ASA’s plant no.2 in Glomfjord.
The large growth in the Photo Voltaic industry necessitates a dedicated feedstock for this industry, a socalled Solar Grade (SoG) feedstock, since the currently used feedstock rejects from the electronic industry can not cover the demand. Part I of this work was motivated by this urge for a SoG- feedstock. It was a cooperation with the Sintef Materials and Chemistry group, where the aim was to study the kinetics of the removal reactions for dissolved carbon and boron in a silicon melt by oxidative gas treatment. The main focus was on carbon, since boron may be removed by other means. A plasma arc was employed in combination with inductive heating. The project was, however, closed after only two experiments. The main observations from these two experiments were a significant boron removal, and the formation of a silica layer on the melt surface when the oxygen content in the gas was increased from 2 to 4 vol%. This silica layer inhibited further reactions.
Multi-crystalline (mc) silicon produced by directional solidification constitutes a large part of the solar cell market today. Other techniques are emerging/developing and to keep its position in the market it is important to stay competitive. Therefore increasing the knowledge on the material produced is necessary. Gaining knowledge also on phenomenas occurring during the crystallisation process can give a better process control.
Part II of this work was motivated by the industry reporting high inclusion contents in certain areas of the material. The aim of the work was to increase the knowledge of inclusion formation in this system. The experimental work was divided into three different parts;
1) Inclusion study
2) Extraction of melt samples during crystallisation, these were to be analysed for carbon- and nitrogen. Giving thus information of the contents in the liquid phase during soldification.
3) Fourier Transform Infrared Spectroscopy (FTIR)-measurements of the substitutional carbon contents in wafers taken from similar height positions as the melt samples. Giving thus information of the dissolved carbon content in the solid phase.
The inclusion study showed that the large inclusions found in this material are β-SiC and β-Si3N4. They appear in particularly high quantities in the top-cuts. The nitrides grow into larger networks, while the carbide particles tend to grow on the nitrides. The latter seem to act as nucleating centers for carbide precipitation. The main part of inclusions in the topcuts lie in the size range from 100- 1000 µm in diameter when measured by the Coulter laser diffraction method.
A method for sampling of the melt during crystallisation under reduced pressure was developed, giving thus the possibility of indicating the bulk concentration in the melt of carbon and nitrogen. The initial carbon concentration was measured to ~30 and 40 ppm mass when recycled material was employed in the charge and ~ 20 ppm mass when no recycled material was added. Since the melt temperature at this initial stage is ~1500 °C these carbon levels are below the solubility limit. The carbon profiles increase with increasing fraction solidified. For two profiles there is a tendency of decreasing contents at high fraction solidified.
For nitrogen the initial contents were 10, 12 and 44 ppm mass. The nitrogen contents tend to decrease with increasing fraction solidified. The surface temperature also decreases with increasing fraction solidified. Indicating that the melt is saturated with nitrogen already at the initial stage. The proposed mechanism of formation is by dissolution of coating particles, giving a saturated melt, where β-Si3N4 precipitates when cooling. Supporting this mechanism are the findings of smaller nitride particles at low fraction solidified, that the precipitated phase are β-particles, and the decreasing nitrogen contents with increasing fraction solidified.
The carbon profile for the solid phase goes through a maximum value appearing at a fraction solidified from 0.4 to 0.7. The profiles flatten out after the peak and attains a value of ~ 8 ppma. This drop in carbon content is associated with a precipitation of silicon carbide. It is suggested that the precipitation of silicon carbide occurs after a build-up of carbon in the solute boundary layer.
FTIR-measurements for substitutional carbon and interstitial oxygen were initiated at the institute as a part of the work. A round robin test was conducted, with the Energy Research Centre of the Netherlands (ECN) and the University of Milano-Bicocci (UniMiB) as the participants. The measurements were controlled against Secondary Ion Mass Spectrometer analyses. For oxygen the results showed a good correspondence between the FTIR-measurements and the SIMS. For carbon the SIMS-measurements were significantly lower than the FTIR-measurements. This is probably due to the low resistivity of the samples (~1 Ω cm), giving free carrier absorption and an overestimation of the carbon content.
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Falkenberg, Christiane. "Optimizing Organic Solar Cells." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-89214.
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This thesis deals with the characterization and implementation of transparent electron transport materials (ETM) in vacuum deposited p-i-n type organic solar cells (OSC) for substituting the parasitically absorbing standard ETM composed of n-doped C60. In addition to transparency in the visible range of the sun spectrum, the desired material properties include high electron mobility and conductivity, thermal and morphological stability, as well as good energy level alignment relative to the adjacent acceptor layer which is commonly composed of intrinsic C60. In this work, representatives of three different material classes are evaluated with regard to the above mentioned criteria.
HATCN (hexaazatriphenylene hexacarbonitrile) is a small discoid molecule with six electron withdrawing nitrile groups at its periphery. It forms smooth thin films with an optical energy gap of 3.3eV, thus being transparent in the visible range of the sun spectrum. Doping with either 5wt% of the cationic n-dopant AOB or 7wt% of the proprietary material NDN1 effectively increases the conductivity to 7.6*10^-6 S/cm or 2.2*10^-4 S/cm, respectively. However, the fabrication of efficient OSC is impeded by the exceptionally high electron affinity (EA ) of approximately 4.8eV that causes the formation of an electron injection barrier between n-HATCN and intrinsic C60 (EA=4.0eV). This work presents a strategy to remove the barrier by introducing doped and undoped C60 intermediate layers, thus demonstrating the importance of energy level matching in a multi-layer structure and the advantages of Fermi level control by doping.
Next, a series of six Bis-Fl-NTCDI (N,N-bis(fluorene-2-yl)-naphthalenetetracarboxylic diimide) compounds, which only differ by the length of the alkyl chains attached to the C9 positions of the fluorene side groups, is examined. When increasing the chain length from 0 to 6 carbon atoms, the energy levels remain nearly unchanged: We find EA=3.5eV as estimated from cyclic voltammetry, an ionization potential (IP ) in the range between 6.45eV and 6.63eV, and Eg,opt=3.1eV which means that all compounds form transparent thin films. Concerning thin film morphology, the addition of side chains results in the formation of amorphous layers with a surface roughness <1nm on room temperature glass substrates, and (1.5+/-0.5)nm for deposition onto glass substrates heated to 100°C. In contrast, films composed of the side chain free compound Bis-HFl-NTCDI exhibit a larger surface roughness of (2.5+/-0.5)nm and 9nm, respectively, and are nanocrystalline already at room temperature. Moreover, the conductivity achievable by n-doping is very sensitive to the side chain length: Whereas doping of Bis-HFl-NTCDI with 7wt% NDN1 results in a conductivity in the range of 10^-4 S/cm, the attachment of alkyl chains causes a conductivity which is more than three orders of magnitude smaller despite equal or slightly higher doping concentrations. The insufficient transport properties of the alkylated derivatives lead to the formation of pronounced s-kinks in the jV -characteristics of p-i-n type OSC while the use of n-Bis-HFl-NTCDI results in well performing devices.
The last material, HATNA-Cl6 (2,3,8,9,14,15- hexachloro-5,6,11,12,17,18-hexaazatrinaphthylene), exhibits Eg,opt=2.7eV and is therefore not completely transparent in the visible range of the sun spectrum. However, its energy level positions of EA=4.1eV and IP=7.3eV are well suited for the application as ETM in combination with i-C60 as acceptor. The compound is dopable with all available n-dopants, resulting in maximum conductivities of sigma=1.6*10^-6, 3.5*10^-3, and 7.5*10^-3 S/cm at 7.5wt% AOB, Cr2(hpp)4, and NDN1, respectively. Applying n-HATNA-Cl6 instead of the reference ETM n-C60 results in a comparable or improved photocurrent density at an ETM thickness d(ETM)=40nm or 120nm, respectively. At d(ETM)=120nm, the efficiency eta is more than doubled as it increases from eta(n-C60)=0.4% to eta(n-HATNA-Cl6)=0.9% .
Optical simulations show that the replacement of n-C60 by n-Bis-HFl-NTCDI, n-HATNA-Cl6, or the previously studied n-NTCDA (naphthalenetretracarboxylic dianhydride) in p-i-n or n-i-p type device architectures is expected to result in an increased photocurrent due to reduced parasitic absorption. For quantifying the gain, the performance of p-i-n type OSC with varying ETM type and thickness is evaluated. Special care has to be taken when analyzing devices comprising the reference ETM n-C60 as its conductivity is sufficiently large to extend the area of the aluminum cathode and thus the effective device area which may lead to distorted results. Overall, the experiment is able to confirm the trends predicted by the optical simulation. At large ETM thickness in the range between 60 and 120nm, the window layer effect of the ETM is most pronounced. For instance, at d(ETM)=120nm, eta(C60) is more than doubled using n-HATNA-Cl6 and even more than tripled using n-Bis-HFl-NTCDI or n-NTCDA. At optimized device geometry the photocurrent gain is slightly less than expected but nonetheless, the efficiency is improved from eta(max)=2.1% for n-C60 and n-HATNA-Cl6 solar cells to eta(max)=2.3, and 2.4% for n-Bis-HFl-NTCDI and n-NTCDA devices, respectively. This development is supported by generally higher Voc and FF in solar cells with transparent ETM.
Finally, p-i-n type solar cells with varying ETM are aged at a temperature of 50°C and an illumination intensity of approximately 2 suns. Having extrapolated lifetimes t(80) of 36, 500, and 14000h and nearly unchanged jV-characteristics after 2000h, n-C60 and n-Bis-HFl-NTCDI devices exhibit the best stability. In contrast, n-NTCDA devices suffer from a constant decrease in Isc while n-HATNA-Cl6 solar cells show a rapid dscegradation of both Isc and FF associated with a decomposition of the material or a complete de-doping of the ETM. Here, lifetimes of only 4500h and 445hare achieved.
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Hadipour, Afshin. "Polymer tandem solar cells." [S.l. : Groningen : s.n. ; University Library of Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/305349066.
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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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Cattley, Christopher Andrew. "Quaternary nanocrystal solar cells." Thesis, University of Oxford, 2016. http://ora.ox.ac.uk/objects/uuid:977e0f75-e597-4c7a-8f72-6a26031f8f0b.
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This thesis studies quaternary chalcogenide nanocrystals and their photovoltaic applications. A temperature-dependent phase change between two distinct crystallographic phases of stoichiometric Cu2ZnSnS4 is investigated through the development of a one pot synthesis method. Characterisation of the Cu2ZnSnS4 nanocrystals was performed using absorption spectroscopy, transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). An investigation was conducted into the effects of using hexamethyldisilathiane (a volatile sulphur precursor) in the nucleation of small (<7nm), mono-dispersed and solution-stable quaternary Cu2ZnSnS4 nanocrystals. A strategy to synthesize high quality thermodynamically stable kesterite Cu2ZnSnS4 nanocrystals is established, which subsequently enabled the systematic study of Cu2ZnSnS4 nanocrystal formation mechanisms, using optical characterization, XRD, TEM and Raman spectroscopy. Further studies employed scanning transmission electron microscopy (STEM) energy dispersive x-ray (EDX) mapping to examine the elemental spatial distributions of Cu2ZnSnS4 nanocrystals, in order to analyse their compositional uniformity. In addition, the stability of nanocrystals synthesised using alternative ligands is investigated using Fourier transform infrared spectroscopy, without solution based ligand substitution protocol is used to replace aliphatic reaction ligands with short, aromatic pyridine ligands in order to further improve Cu2ZnSnS4 colloid stability. A layer-by-layer spin coating method is developed to fabricate a semiconductor heterojunction, using CdS as an n-type window, which is utilised to investigate the photovoltaic properties of Cu2ZnSnS4 nanocrystals. Finally, three novel passivation techniques are investigated, in order to optimise the optoelectronic properties of the solar cells to the point where a power conversion efficiency (PCE) of 1.00±0.04% is achieved. Although seemingly modest when compared to the performance of leading devices (PCE>12%) this represents one of the highest obtained for a Cu2ZnSnS4 nanocrystal solar cell, fabricated completely under ambient conditions at low temperatures.
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Essner, Jeremy. "Dye sensitized solar cells: optimization of Grätzel solar cells towards plasmonic enhanced photovoltaics." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/12416.
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Master of ScienceDepartment of Chemistry
Jun Li
With the worldly consumption of energy continually increasing and the main source of this energy, fossil fuels, slowly being depleted, the need for alternate sources of energy is becoming more and more pertinent. One promising approach for an alternate method of producing energy is using solar cells to convert sunlight into electrical energy through photovoltaic processes. Currently, the most widely commercialized solar cell is based on a single p-n junction with silicon. Silicon solar cells are able to obtain high efficiencies but the downfall is, in order to achieve this performance, expensive fabrication techniques and high purity materials must be employed. An encouraging cheaper alternative to silicon solar cells is the dye-sensitized solar cell (DSSC) which is based on a wide band gap semiconductor sensitized with a visible light absorbing species. While DSSCs are less expensive, their efficiencies are still quite low compared to silicon. In this thesis, Grätzel cells (DSSCs based on TiO2 NPs) were fabricated and optimized to establish a reliable standard for further improvement. Optimized single layer GSCs and double layer GSCs showing efficiencies >4% and efficiencies of ~6%, respectively, were obtained. Recently, the incorporation of metallic nanoparticles into silicon solar cells has shown improved efficiency and lowered material cost. By utilizing their plasmonic properties, incident light can be scattered, concentrated, or trapped thereby increasing the effective path length of the cell and allowing the physical thickness of the cell to be reduced. This concept can also be applied to DSSCs, which are cheaper and easier to fabricate than Si based solar cells but are limited by lower efficiency. By incorporating 20 nm diameter Au nanoparticles (Au NPs) into DSSCs at the FTO/TiO2 interface as sub wavelength antennae, average photocurrent enhancements of 14% (maximum up to ~32%) and average efficiency enhancements of 13% (maximum up to ~23% ) were achieved with well dispersed, low surface coverages of nanoparticles. However the Au nanoparticle solar cell (AuNPSC) performance is very sensitive to the surface coverage, the extent of nanoparticle aggregation, and the electrolyte employed, all of which can lead to detrimental effects (decreased performances) on the devices.
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Kwarikunda, Nicholas. "On the characterisation of solar cells using light beam induced current measurements." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/11147.
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The presence of inhomogeneities in semiconductor materials used to fabricate solar cell devices may result in spatial non uniformities in the device properties which may affect current generation in these devices. Besides, current reducing defects such as inclusions, local shunts and optical blockages may be introduced during the various device manufacturing processes which may adversely affect the performance and overall efficiency of solar cells. Diagnostic techniques are therefore needed to identify these defects so as to improve the production technology. This thesis presents the Light Beam Induced Current (LBIC) technique for mapping spatial non uniformities in solar cell devices. The LBIC is a non destructive characterisation technique that uses a focused light beam to raster scan a solar cell surface as the photo-generated current is recorded as a function of position to generate a photo-response map. The technique was used to obtain photoresponse maps for a mc-Si, Back contact Back junction (BC-BJ) silicon solar cell and the InGaP/InGaAs/Ge concentrating triple junction (CTJ) solar cell from which various local current reducing defects were mapped. A reflection signal detector was incorporated into the LBIC measurement system to enable us distinguish between optical blockages on the cell surface and current reducing defects within the solar cell devices. By dynamically biasing the solar cell devices, the electrical activity of the identified defects was investigated and also point-by-point current-voltage (I-V) characteristics were obtained. An interval division algorithm was applied to the measured point-by-point I-V characteristics to extract device and performance parameters from which device and performance parameter uniformity of the devices were mapped. Dark and full cell solar illumination I-V characteristics were also measured to extract device parameters. Analysis of extracted parameters revealed differences between extracted dark and illuminated device parameters which was attributed to departure from the superposition principle due to non-linearity of the semiconductor device equations with respect to carrier concentration. An investigation into the effect of illumination intensity on the I-V parameters of a spot illuminated BC-BJ Si solar cell showed a linear increase and a logarithmic increase of the short circuit current and open circuit voltage respectively with intensity while the series resistance decreased with intensity, which was attributed to increase in conductivity of the active layer. The ideality factor and saturation current were observed to increase while the shunt resistance initially increased before decreasing at higher intensity levels. Under monochromatic illumination, the photo-response of the BC-BJ Si cell was higher at 785nm than at 445nm due to low absorption coefficient of Si for longer wavelength radiations, resulting in carrier generation within the bulk, where there is a higher probability of carriers being collected at the p-n junction before they recombine. Under solar illumination, as the spectral content was altered using long pass colour filters with cut off wavelengths of 610nm and 1000nm, the performance parameters were observed to decrease and this was mainly due to decrease in intensity. For the CTJ solar cell, however, blocking of radiations below 610nm resulted in current mismatch that severely degraded the short circuit current (Isc). The current mismatch affected the extracted device and performance parameters. With a 1000nm long pass filter, a dark I-V was obtained since only the bottom Ge subcell was activated.
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Nygren, Martin Alexander. "Solar Simulation for the NTNU Test Satellite Solar Cells." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24434.
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The relevant energy theory behind intensity and spectral irradiance from the sun is discussed with regard to how it changes due to factors like Earth-Sun distance, solid angle of the sun disk and circumsolar region, angle of incidence and atmospheric mass. This translates to how the experienced conditions for solar cells vary, how and why solar simulation is done the way it is with such stringent requirements, as well as what can be expected in terms of difference between controlled, fixed conditions and operation in environments where we are not free to modify the variables as easily. The most essential theory of solar cell structure and performance is reviewed, with emphasis on the theory needed to understand the design principles, characteristics and behavior of the high-efficiency multijunction solar cells available for the NUTS project. The most commonly encountered components of a solar simulator is discussed to the point where the information provided should allow for a well-informed evaluation and selection of design for most applications, and be of guidance if one were to wish to attempt to create a device able to simulate aspects of the solar irradiation.Solar cell characteristics are developed by the use of a solar simulator under controlled testing conditions to ensure reproducible results. The effect of controlled sunlight from a range of different angles onto a solar cell is investigated in terms of current-voltage characteristics, and in particular the effect on short circuit current as compared to what is expected of theory. It is found that the angle of incidence of light can be calculated from the measured current with a general accuracy of about 1 degree, when compensating for reflectivity in the solar cell cover glass.
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Kang, Moon Hee. "Development of high-efficiency silicon solar cells and modeling the impact of system parameters on levelized cost of electricity." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47647.
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The objective of this thesis is to develop low-cost high-efficiency crystalline silicon solar cells which are at the right intersection of cost and performance to make photovoltaics (PV) affordable. The goal was addressed by improving the optical and electrical performance of silicon solar cells through process optimization, device modeling, clever cell design, fundamental understanding, and minimization of loss mechanisms. To define the right intersection of cost and performance, analytical models to assess the premium or value associated with efficiency, temperature coefficient, balance of system cost, and solar insolation were developed and detailed cost analysis was performed to quantify the impact of key system and financial parameters in the levelized cost of electricity from PV.
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Tarabsheh, Anas al. "Amorphous silicon based solar cells." kostenfrei, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29491.
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Anderson, Ingrid E. "All-inorganic nanoparticle solar cells /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2009. http://uclibs.org/PID/11984.
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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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Guram, Prabhjot Kaur. "Modeling solar cells with recombination." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39887.
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An elementary model for the analysis of a photovoltaic solar cell is proposed.
This analysis is rooted in the current-voltage device characteristics
associated with a p-n junction in conjunction with a model for a solar
flux
controlled current source; this follows the approach of Prince [M. B. Prince,
Journal of Applied Physics, vol. 26, pp. 553-540, 1955], the p-n junction architecture
being that underlying the photovoltaic solar cell. Recombination
processes were modeled through two means: (1) an empirical expression for
the current-voltage device characteristics with an associated ideality factor, whose value determines the importance of recombination processes, and
(2) a more advanced expression that includes a recombination current. It is
shown that the simplified empirical expression is overly simplified and that
its use leads to artifacts, i.e., the suggestion that recombination processes
could actually enhance the fill-factor. In contrast, the more realistic current voltage
device characteristic, which includes both ideal and recombination
related current densities, suggests that recombination processes actually will
reduce the fill-factor. This later observation is in accord with the experimental
observation.
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鄺頌賢 and Chung-yin Calvin Kwong. "Phthalocyanine based organic solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226152.
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鄭旭 and Yuk Cheng. "Interdiffused quantum well solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31213996.
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Li, Xuanhua, and 李炫华. "Plasmonic-enhanced organic solar cells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/197526.
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Organic solar cells (OSCs) have recently attracted considerable research interest. However, there is a mismatch between their optical absorption length and charge transport scale. Attempts to optimize both the optical and electrical properties of the photoactive layer of OSCs have inevitably resulted in demands for rationally designed device architecture. Plasmonic nanostructures have recently been introduced into solar cells to achieve highly efficient light harvesting. The remaining challenge is to improve OSC performance using plasmonic nanotechnology, a challenge taken up by the research reported in this thesis. I systematically investigated two types of plasmonic effect: localized plasmonic resonances (LPRs) and surface plasmonic resonances (SPRs).
Broadband plasmonic absorption is obviously highly desirable when the LPR effect is adopted in OSCs. Unfortunately, typical nanomaterials possess only a single resonant absorption peak, which inevitably limits the power conversion efficiency (PCE) enhancement to a narrow spectral range. To address this issue, I combined Ag nanomaterials of different shapes, including nanoparticles and nanoprisms. The incorporation of these mixed nanomaterials into the active layer resulted in wide band absorption improvement. My results suggest a new approach to achieving greater overall enhancement through an improvement in broadband absorption.
I also explored the SPR effect induced by a metal patterned electrode with two parts. Most reports to date on back reflector realization involve complicated and costly techniques. In this research, however, I adopted a polydimethylsiloxane (PDMS)-nanoimprinted method to produce patterned back electrodes in OSCs directly, which is a very simple and efficient technique for realizing high-performance OSCs in industrial processes. Besides, a remaining challenge is that plasmonic effects are strongly sensitive to light polarization, which limits plasmonic applications in practice. To address this issue, I designed three-dimensional patterns as the back electrode of inverted OSCs, which simultaneously achieved highly efficient and polarization-independent plasmonic OSCs.
In addition to investigating the two types of plasmonic effect individually, I also investigated their integrated function by introducing both LPRs and SPRs in one device structure. With the aim of achieving high-performance OSCs, I first demonstrated experimentally a dual metal nanostructure composed of Au nanoparticles (i.e. LPRs) embedded in the active layer and an Ag nanograting electrode (i.e. SPRs) as the back reflectors in inverted OSCs, which can generate a very strong electric field, in a single junction to improve the light absorption of solar cells. As a result, the PCE of the OSC reached 9.1%, making it one of the best-performing OSCs reported to date. In addition, as an important extension, I subsequently achieved tremendous near-field enhancement owing to multiple couplings, including nanoparticle-nanoparticle (LPR-LPR) couplings and nanoparticle-film (LPR-SPR) couplings, by designing a novel nanoparticle-film coupling system through the introduction of ultrathin monolayer graphene as a well-defined sub-nanogap between the Ag nanoparticles and Ag film. The graphene sub-nanogap is the thinnest nanogap (in atomic scale terms) to date, and thus constitutes a promising light-trapping strategy for improving future OSC performance.published_or_final_version
Electrical and Electronic Engineering
Doctoral
Doctor of Philosophy
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Awan, G. R. "Cadmium telluride for solar cells." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6852/.
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Cadmium telluride is an attractive material for solar cell applications because of its near optimum bandgap and high absorption coefficient. This thesis presents the results of a study into the use of CdTe for solar cells. Three types of cell have been investigated, namely; CdS/CdTe devices fabricated by the vacuum evaporation of CdS onto either: (a) single crystal p-CdTe substrates or (b) p-CdTe thin films, and (c) p-Cu(_2)Te/n-CdTe devices made by a chemiplating process onto single crystal n-CdTe. The effects of substrate polishing and preparation on the performance of CdS/CdTe bulk crystal cells have been Investigated together with the problems of doping and contacting to p-type CdTe. These studies have shown that the best results are obtained with devices that have been prepared on pad polished, phosphorus doped substrates using carbon contacts (efficiency = 7.2%). The influence of deposition conditions on the electrical and structural properties of thin CdS and CdTe layers, and their effect on CdS/CdTe device efficiency were also studied, and optimum growth conditions established. In the third group of CU(_2)Te/CdTe solar cells a number of structural and electrical aspects such as the phase of Cu(_2)Te, and the Influence of dopants, substrate resistivity and preparation and ageing on cell efficiency have been examined. As secondary objectives, an investigation Into the epitaxial growth of CdS on CdTe, and the characterisation of as-grown and doped CdTe have been carried out. It has been shown that epitaxy is possible on the {111} and {221} faces of CdTe. The characterisation of CdTe has revealed the presence of dominant levels at energies above the valence band of 0.50 eV in the as-grown crystals; 0.53, 0.71 and 0.84 eV in Te-annealed single crystals; and 0.35 eV in Cu doped CdTe thin films.
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Heffernan, Shane. "Nanostructured CU₂O solar cells." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709220.
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Risbridger, Thomas Arthur George. "Aqueous dye sensitized solar cells." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607628.
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Dye sensitized solar cells (DSSCs) have typically been produced using organic liquids such as acetonitrile as the electrolyte solvent. In real world situations water can permeate into the cell through sealing materials and is also likely to be introduced during the fabrication process. This is a problem as the introduction of water into cells optimized to use an organic solvent tends to be detrimental to cell performance. In this work DSSCs which are optimized to use water as the main electrolyte solvent are produced and characterized. Optimization of aqueous DSSCs resulted in cells with efficiencies up to 3.5% being produced. In terms of characterization, it is generally seen in this work that aqueous DSSCs produce a lower photocurrent but similar photovoltage compared to DSSCs made using acetonitrile and reasons for this are examined in detail. The decreased ability of the aqueous electrolyte to wet the nanoporous TiO2 compared to an acetonitrile electrolyte is found to be a key difficulty and several possible solutions to this problem are examined. By measuring the photocurrent output of aqueous cells as a function of xy position it can be seen that there is some dye dissolution near to the electrolyte filling holes. This is thought to be linked to pH and the effect of 4-tert-butylpyridine and may also decrease the photocurrent. It is found that there is little difference between the two types of cells in terms of the conduction band position and the reaction of electrons in the semiconductor with triiodide in the electrolyte, explaining the similarity in photovoltage. By altering the pH of the electrolyte in an aqueous cell it is found to be possible to change the TiO2 conduction band position in the DSSC. This has a significant effect on the open circuit voltage and short circuit current of the cell, though the pH range available is limited by the fact that dye desorbs at high pH values.
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Pockett, Adam. "Characterization of perovskite solar cells." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715261.
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A range of electrical characterization techniques previously used for DSSC have been transferred to the study of planar perovskite devices. These include impedance spectroscopy (EIS), intensity modulated photovoltage spectroscopy (IMVS) and open-circuit voltage decay measurements (OCVD). An investigation into the observed response from these measurements has been carried out in order to gain a deeper understanding of device operation. Multiple processes with time constants on the microsecond, millisecond and second timescale were observed. The complimentary frequency and time domain techniques have been employed, showing excellent agreement between the two types of measurement. The high frequency (microsecond) process was found to be purely electronic in nature, which was linked to recombination. The geometric capacitance was shown to dominate this response, with accumulation of charge in the planar perovskite layer not observed. The lower frequency (millisecond and second timescale) processes were found to be linked to the coupling between recombination and the movement of ions. The low frequency EIS and IMVS measurements revealed that the recombination resistance was frequency dependent. The rate of change of the recombination resistance was found to be linked to the diffusion of ionic species. Activation energies for these processes were obtained (EA=0.55-0.66 eV) and shown to be in good agreement to computationally calculated values from literature for iodide vacancy migration. The same slow processes were also studied in the time domain using open-circuit photovoltage rise and decay measurements from well-defined equilibrium conditions. Comparable activation energies were also found using these techniques. The vacancy defect concentration was calculated to be 3x1019 cm-3, which is high enough for ionic double layers at the contacts to completely screen the built-in voltage across the perovskite at equilibrium in the dark. The slow dynamic processes observed under illumination or applied bias are therefore due to the rearrangement of ions in response to a changing electric field. As this rearrangement occurs, the rate of recombination is altered.
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Vandamme, Nicolas. "Nanostructured ultrathin GaAs solar cells." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112111/document.
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L’amincissement des cellules solaires semi-conductrices est motivé par la réduction des coûts de production et l’augmentation des rendements de conversion. Mais en deçà de quelques centaines de nanomètres, il requiert de nouvelles stratégies de piégeage optique. Nous proposons d’utiliser des concepts de la nanophotonique et de la plasmonique pour absorber la lumière sur une large bande spectrale dans des couches ultrafines de GaAs. Nous concevons et fabriquons pour ce faire des structures multi-résonantes formées de réseaux de nanostructures métalliques. Dans un premier temps, nous montrons qu’il est possible de confiner la lumière dans une couche de 25 nm de GaAs à l’aide d’une nanogrille bidimensionnelle pouvant servir de contact électrique en face avant. Nous analysons numériquement les modes résonants qui conduisent à une absorption moyenne de 80% de la lumière incidente entre 450 nm et 850 nm. Ces résultats sont validés par la fabrication et la caractérisation de super-absorbeurs ultrafins multi-résonants. Dans un second temps, nous appliquons une approche similaire dans le but d’obtenir des cellules photovoltaïques dix fois plus fines que les cellules GaAs records, avec des absorbeurs de 120 nm et 220 nm seulement. Un miroir arrière nanostructuré en argent, associé à des contacts ohmiques localisés, permet d’améliorer l’absorption tout en garantissant une collecte optimale des porteurs photo-générés. Nos calculs montrent que les densités de courant de court-circuit (Jsc) dans ces structures optimisées peuvent atteindre 22.4 mA/cm2 et 26.0 mA/cm2 pour les absorbeurs d’épaisseurs respectives t=120 nm et t=220 nm. Ces performances sont obtenues grâce à l’excitation d’une grande variété de modes résonants (Fabry-Pérot, modes guidés,…). En parallèle, nous avons développé un procédé de fabrication complet de ces cellules utilisant la nano-impression et le transfert des couches actives. Les mesures montrent des Jsc records de 17.5 mA/cm2 (t=120 nm) et 22.8 mA/cm2 (t=220 nm). Ces résultats ouvrent la voie à l’obtention de rendements supérieurs à 20% avec des cellules solaires simple jonction d’épaisseur inférieure à 200 nmThe thickness reduction of solar cells is motivated by the reduction of production costs and the enhancement of conversion efficiencies. However, for thicknesses below a few hundreds of nanometers, new light trapping strategies are required. We propose to introduce nanophotonics and plasmonics concepts to absorb light on a wide spectral range in ultrathin GaAs layers. We conceive and fabricate multi-resonant structures made of arrays of metal nanostructures. First, we design a super-absorber made of a 25 nm-thick GaAs slab transferred on a back metallic mirror with a top metal nanogrid that can serve as an alternative front electrode. We analyze numerically the resonance mechanisms that result in an average light absorption of 80% over the 450nm-850nm spectral range. The results are validated by the fabrication and characterization of these multi-resonant super-absorbers made of ultrathin GaAs. Second, we use a similar strategy for GaAs solar cells with thicknesses 10 times thinner than record single-junction photovoltaic devices. A silver nanostructured back mirror is used to enhance the absorption efficiency by the excitation of various resonant modes (Fabry-Perot, guided modes,…). It is combined with localized ohmic contacts in order to enhance the absorption efficiency and to optimize the collection of photogenerated carriers. According to numerical calculations, the short-circuit current densities (Jsc) can reach 22.4 mA/cm2 and 26.0 mA/cm2 for absorber thicknesses of t=120 nm and t=220 nm, respectively. We have developed a fabrication process based on nano-imprint lithography and on the transfer of the active layers. Measurements exhibit record short-circuit currents up to 17.5 mA/cm2 (t=120 nm) and 22.8 mA/cm2 (t=220 nm). These results pave the way toward conversion efficiencies above 20% with single junction solar cells made of absorbers thinner than 200 nm
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Howells, Thomas J. "Asymmetric tandem organic solar cells." Thesis, University of Warwick, 2011. http://wrap.warwick.ac.uk/50330/.
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Organic photovoltaics (OPVs) is an area that has attracted much attention recently as a potential low cost, sustainable source of energy with a good potential for full-scale commercialisation. Understanding the factors that determine the efficiency of such cells is therefore a high priority, as well as developing ways to boost efficiency to commercially-useful levels. In addition to an intensive search for new materials, significant effort has been spent on ways to squeeze more performance out of existing materials, such as multijunction cells. This thesis investigates double junction tandem cells in the context of small molecule organic materials. Two different organic electron donor materials, boron subphthalocyanine chloride (SubPc) and aluminium phthalocyanine chloride (ClAlPc) were used as donors in heterojunctions with C60 to create tandem cells for this thesis. These materials have been previously used for solar cells and the absorption spectra of the donor materials complement each other, making them good candidates for tandem cell architectures. The design of the recombination layer between the cells is considered first, with silver nanoparticles demonstrated to work well as recombination centres for charges from the front and back sub-cells, necessary to avoid a charge build-up at the interface. The growth conditions for the nanoparticles are optimised, with the tandem cells outperforming the single heterojunction architecture. Optical modelling is considered as a method to improve the understanding of thin film solar cells, where interference effects from the reflective aluminium electrode are important in determining the magnitude of absorption a cell can achieve. The use of such modelling is first demonstrated in hybrid solar cells based on a SubPc donor with a titanium oxide (TiOx) acceptor; this system is ideal for observing the effects of interference as only the SubPc layer has significant absorption. The modelling is then applied to tandem cells where it is used to predict the short-circuit current (Jsc) generation of the sub-cells, which is not accessible experimentally. Current-matching is then used to predict the Jsc of the complete tandem device. As a support to the optical modelling, ellipsometry measurements of thin films of ClAlPc are presented. These films of known thickness are analysed to extract the complex refractive index for use in optical modelling calculations. A dependence of the complex refractive index on film thickness and substrate is also noted. Finally, the external quantum efficiency (EQE) technique is considered as applied to solar cells, and an additional method is proposed to characterise current balancing in asymmetric tandem cells under illumination. This technique is verified experimentally by two separate sets of data.
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Gunaicha, Purnaansh Prakash. "Optical Modeling of Solar Cells." University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1344815193.
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Gowrishankar, Vignesh. "Nanostructured inorganic / polymer solar cells /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Al, Tarabsheh Anas. "Amorphous silicon based solar cells." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29491.
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Cheng, Yuk. "Interdiffused quantum well solar cells /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19740049.
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Kwong, Chung-yin Calvin. "Phthalocyanine based organic solar cells /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25100701.
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Zhang, Nanlin. "Collodial quantum dot solar cells." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:76dd4ff5-abc6-4f47-91d1-8cdc65362b12.
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This thesis presents three specific strategies to enhance colloidal quantum dot (CQD) solar cells' performances, including band alignment engineering, quantum dot passivation, and smart device architecture design. Firstly, by inserting a PbS CQD layer with a relatively smaller band gap as the hole transport layer (HTL), the carrier extraction of the solar cells is much improved, so as the efficiency. The improvement is due to a better interfacial band alignment between the HTLs and the absorber layer, proved by Kelvin probe and cyclic voltammetry results. Small band gap PbS CQDs have deeper Fermi levels because of the easy oxidation. Coupled with a p-type inducing ligand, 1,2-ethanedithiol (EDT), a better valence band alignment is achieved to extract the holes more efficiently. Secondly, alcohol-dissolvable CsI is used as the ligands to passivate QDs' surface with the aim of reducing dangling bonds and defects on the surface. Compared to the commonly used ligand, tetrabutylammonium iodide (TBAI), CsI resulted in better passivation, which was proved by the full ligand exchange, a narrow photoluminescence peak, fewer oxide defects, and the existence of Cs-S bond. A high efficiency of 10% is achieved, which is attributed to that fewer defects and better passivation lead to larger depletion region pushing its optimal thickness and current output higher, as well as the efficiency. Thirdly, a microgroove-structured flexible PbS CQD micro-module solar cell is reported for the first time with a record Voc of 9.2 V. This device was fabricated by automatic dip coating methods, and it avoids the complex recombination layers required in monolithic tandem devices. By e-beam depositing two electrodes on the two walls of the V-shape grooves, devices were connected in series in less than 100 Î1⁄4m width. By using three-dimensional characterisations, the reasons for low efficiency were explained.
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Griffitts, Fletcher G. "Fullerenes in Solar Energy Cells." Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/honors/394.
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This project involves controlling and characterizing the morphology of the active layer in a special type of organic photovoltaics (OPVs), consisting of porphyrin-fullerene composites, with emphasis on electron exchange interactions between the two components. The Vienna Ab Initio Simulation Package (VASP) is applied to model a variety of donor-acceptor complexes containing fullerene and porphyrin in terms of their stabilities as well as their geometric, electronic, and charge transfer features. The goal is to identify supramolecular chain structures with highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) that may serve as electron (hole) transfer channels in a photovoltaic device.
A stable structure, involving the planar adsorption of a porphyrin unit on a C60 hexagon, has been identified. The results for fullerene have been extended to phthalocyanine–fullerene dyads where the fullerene-derived unit Phenyl-C61-butyric acid methyl ester (PCBM) is connected to a porphyrin analogous electron donor through two oxygen-linked benzene rings. In both cases, the HOMO is located on the porphyrin segment, the LUMO on the fullerene component. As a fullerene, PCBM is a material of very high electron affinity, but it has better solubility properties than fullerene. It is often used in plastic solar cells or flexible electronics in conjunction with electron donor materials such as P3HT or other polymers. The results of our work contribute to the ongoing effort of using computational modeling to identify fullerene-based materials of potential relevance for organic photovoltaics.
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Palma, Giuseppina. "Nanostructured dye-sensitized solar cells." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9972.
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2012/2013Dye-sensitized solar cells (DSSCs) represent a promising alternative to silicon-based technology. From the first publications about DSSCs in the 90s, they are considered an important breakthrough for achieving high efficiency by using relatively inexpensive and abundant materials. Stability and efficiency are two crucial points in the development of this new class of hybrid photovoltaic devices. Most of the DSSC studies carried out over the past twenty years are based on the optimization of these two aspects. In particular, no particular efficiency improvement was obtained in the last period, although many efforts have been made for the research of appropriate solutions able to allow to fabricate more efficient devices. In this scenario, the topic of interest for this thesis is to further enhance the photovoltaic performance of DSSCs by integrating a nano-engineered TiOx photoanode obtained by means of a new nanostructuring method. This novel method, called ASB-SANS (Auxiliary Solvent-Based Sublimation-Aided NanoStructuring) allows the fast nanostructuring of a material in conditions of room temperature and atmospheric pressure. The nanostructuring process occurs by means of an auxiliary sublimating substance that, after having influenced the spatial arrangement of the material to be nanostructured, sublimates away from the system spontaneously. So-obtained TiOx photoanodes are characterized by an inner surface area which is higher than that of commonly used photoanodes. This implies that higher dye loading values are possible, in turn meaning an increase of photogenerated charge carriers upon sunlight absorption, hence an overall increase of the DSSC efficiency. This thesis is structured as following: - Chapter 1 is a general introduction to the photovoltaics and dye-sensitized solar cells, such as the operating principles and the characteristics of the dye cell; - Chapter 2 presents the motivation and objectives of PhD work, with particular interest in the state of art on the semiconductor layer optimization; - Chapter 3 contains a description of the two instrumental systems assembled by the author and colleagues for the characterization of photovoltaic devices (current/voltage recording system and IPCE system). A particular focus is put on the development of a tool for the determination of the photovoltaic quantum efficiency obtained by the conversion of a common UV-Vis spectrometer; - Chapter 4 is focused on the description of two methods for the determination of the active sites (dye grafting points) of the TiOx surface: the first based on the acetic acid adsorption and the second on the dye molecules adsorption. These methods are used for the characterization of all fabricated photoanodes; - Chapter 5 starts with the proven effectiveness of the ASB-SANS method applied to nanostructuring, over relatively large areas, a semiconducting polymer widely used in organic solar cells. The chapter is then focused on the description of the ASB-SANS method applied to fabricate our nano-engineered photoanodes; - Chapter 6 presents the results obtained by the application of the nano-engineered photoanodes in photovoltaic devices; - Chapter 7 reports some final conclusions together with our outlooks in the future research and development of the nano-engineered photoanodes for dye-sensitized solar cells.
Le celle solari a colorante organico (DSSC) proposte da Grätzel rappresentano una promettente alternativa alle tecnologie basate sul silicio già in commercio. Dalle prime pubblicazioni negli anni 90 esse hanno reppresentato un importante passo avanti per raggiungere un’efficienza relativamente alta utilizzando materiali poco costosi e abbondanti in natura. Gli aspetti più importanti per lo sviluppo di questa tecnologia sono la stabilità e l’efficienza, su cui si fonda la maggior parte degli studi sulle DSSC condotti negli ultimi vent’anni. In particolare, nonostante gli sforzi enormi nella ricerca di soluzioni appropriate che consentissero di fabbricare dispositivi più efficienti, nessun particolare incremento di efficienze è stato registrato. In questo scenario, il presente lavoro di tesi ha come scopo il miglioramento della performance fotovoltaica di DSSC attraverso l’integrazione al loro interno di un fotoanodo di TiOx nanostrutturato utilizzando un nuovo metodo di fabbricazione. Questo metodo, denominato ASB-SANS (Auxiliary Solvent- Based Sublimation-Aided NanoStructuring) permette la nanostrutturazione di un materiale senza dispendio di tempo ed in condizioni di temperatura ambiente e pressione atmosferica. La nanostrutturazione di un materiale avviene per mezzo di un sublimante ausiliario che, dopo aver influenzato la disposizione spaziale del materiale, si allontana dal sistema spontaneamente per semplice sublimazione. I fotoanodi di TiOx così ottenuti presentano una superficie esposta all’attacco del colorante maggiore di quella esposta generalmente dai fotoanodi comunemente impiegati. Ciò comporta un aumento della quantità di colorante che il fotoanodo può adsorbire che si traduce in un aumento della quantità di portatori di carica che si possono generare per effetto dell’assorbimento della luce solare. Il miglioramento della corrente generata nel dispositivo influenzerà positivamente l’efficienza globale della cella DSSC. Il presente lavoro di tesi è strutturato nel seguente modo: - il Capitolo 1 costituisce l’introduzione alla tematica di interesse con un approfondimento descrittivo dei componenti di una DSSC e del suo funzionamento; - il Capitolo 2 espone la motivazione e gli obbiettivi del lavoro di dottorato con particolare interesse verso lo stato dell’arte inerente alla motivazione espressa; - il Capitolo 3 contiene la descrizione accurata dei sistemi di caratterizzazione di dispositivi fotovoltaici. Di particolare rilievo è la messa a punto di uno strumento per la determinazione dell’efficienza quantica. Quest’ultimo è stato ottenuto assemblando un comune spettrometro UV-Vis con un multimetro per la registrazione delle correnti generate dalla cella; - il Capitolo 4 improntato sulla descrizione di due metodi per la determinazione dei siti attivi (punti di attacco del colorante) presenti sulla superficie del TiOx: il primo basato sull’adsorbimento dell’acido acetico e il secondo sull’adsorbimento delle molecole di colorante. Tali metodi serviranno per la caratterizzazione dei fotoanodi nanostrutturati; - il Capitolo 5 si apre con la provata efficacia del metodo di nanostrutturazione ASB-SANS applicato su polimeri di interesse fotovoltaico. Il fulcro del capitolo è tutto rivolto alla descrizione del metodo applicato al sistema di nanoparticelle di TiOx, con tute le soluzioni tecniche adottate per renderlo altrettanto efficace su questo genere di sistemi; - il Capitolo 6 riporta i risultati ottenuti per l’applicazione dei fotoanodi del capitolo 5 all’interno dei dispositivi fotovoltaici; - il capitolo 7 conclude il lavoro e riporta le eventuali prospettive per il futuro.
XXVI Ciclo
1984
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Wei, Rongsheng. "Modelling of perovskite solar cells." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/119218/1/Rongsheng_Wei_Thesis.pdf.
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This project focuses on simulation performance of perovskite solar cells using two models. One is a simplified model developed for perovskite absorber layer of PSCs by using matlab program to investigate the effect of density of state, relative dielectric permittivity and band gap energy of the perovskite material on the device performance. The other model is based on SCAPS to investigate the influence of hole mobility and band gap offset of different hole transport materials on device performance.
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Tessema, Misle M. "Shunt passivation process for CdTe solar cell : new post deposition technique /." Connect to full text in OhioLINK ETD Center, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1252430254.
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Thesis (M.S.)--University of Toledo, 2009.Typescript. "Submitted as partial fulfillment of the requirements for The Master of Science degree in Chemistry." "A thesis entitled"--at head of title. Bibliography: leaves 75-77.
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Gugole, Marika. "Development and characterisation of silicon solar cells with recombination interconnects for future tandem solar cells." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355765.
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In this project commercial BSF Si solar cells have been processed in order to develop a suitable interconnect for a possible tandem solar cell. The Ag original top contacts have been removed and replaced with TiSi2 formed using the SALICIDE process at 3 different temperatures: 500 °C, 650 °C and 750 °C. Raman spectroscopy and EDS maps have been used to prove the successful formation of the TiSi2 contacts for the 750 °C temperature. As part of this work we also developed a MATLAB script which successfully fits the measured IV curve of a Si solar cell and extrapolates the values of the components of the equivalent circuit. The script also identifies and quantifies the energy losses percentage for different loss mechanisms. The script was used to characterize commercial BSF Si solar cells and to simulate their behavior in a tandem configuration by IV measurements under filtered light. The results of this characterization was used to predict the requirements of a possible top solar cell for a tandem configuration.
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Pan, Jie. "MATERIAL PROPERTY STUDY ON DYE SENSITIZED SOLAR CELLS AND CU(GA,IN)SE2 SOLAR CELLS." Miami University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=miami1240594917.
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Pan, Jie. "Material property study on dye sensitized solar cells and cu(ga,in)se2 solar cells." Oxford, Ohio : Miami University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=miami1240594917.
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Mat-Teridi, Mohd. "Construction of photosensitised semiconductor cathodes." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10286.
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Recent studies suggest that the performance of dye-sensitised solar cells (DSC) has appeared to have reached a limit, therefore solar cells based on semiconductor materials, such as extremely thin absorber (ETA) solar cells and tandem solar cells are currently the subject of intense research in the framework of low-cost photovoltaic devices as sources of harvesting sunlight to generate electricity. Generally, semiconductor solar cells have been divided into two different types, namely anodic and cathodic type solar cells. Extensive research and development work has been focused on anodic semiconductor sensitised solar cells to date. In contrast, the cathodic semiconductor sensitised solar cells have received no attention which is very surprising. Developing the cathodic semiconductor sensitised solar cell concept is very important in the development of tandem solar cells as well as other new solar cell configurations. The main reason for the lack of research in this area was due to the rarity of p-type semiconductor materials, which made it difficult to find suitable materials to match the energy band edges for cathodic semiconductor sensitised solar cells (CSSC) as well as solid-state cathodic semiconductor solar cells (SS-CSSC). The primary aim of this thesis was to construct cathodic semiconductor sensitised solar cells as well as their solid-state analogues (SS-CSSC). The work conducted within this doctoral study presents state-of-art materials and thin film processing/preparation methods, their characterisation and developing CSSCs and SS-CSSCs employing such films in cascade configurations. No reports have been published in the literature on SS-CSSC to date. The first stage of this thesis is focused on optimising the morphology and the texture (porosity) of the CuI and NiO semiconductor photocathode, by the introduction of new deposition methods namely, pulsed-electrodeposition (PED) and Aerosol-Assisted Deposition (AAD) and Aerosol-Assisted Chemical Vapour Deposition (AACVD). The electrodes prepared by employing the methods mentioned above and controlling the deposition parameters systematically, we have achieved significant improvement in the film morphology and the texture of the deposited films. The resulting electrodes showed excellent improvement in the photoelectrochemical performance which made it suitable for application in construction of both CSSC and SS-CSSC. The photoelectrochemical performance of the electrodes can be seen clearly through the photocurrent density data. For the case of bare CuI, the PEC performance of electrode prepared by the AAD and PED compared against that of continuous-electrodeposition (ED) electrodes. The photocurrent density achieved for the electrodes prepared by AAD and PED was reported around 175 and 75 µAcm-2 respectively which are way higher than the ED case. At the second stage of this study, the work focused on fabrication and characterisation of the CSSCs. Cathodic sensitised PEC solar cells (CuI/Cu2S/(Eu2+/Eu3+) and NiO/Cu2S/(I3-/I-)) were fabricated by deposition of p-Cu2S on the texture controlled CuI and NiO photocathodes. The morphological properties of the photocathode, in particular layer thickness, particle size and film porosity, play an important role in the PEC performance of CSSCs. Optimisation of these parameters led to increased adsorption of the Cu2S light harvester on the photocathode s surface. As a result, the charge injection from Cu2S to the wide band gap photocathode material (CuI and NiO) was significantly improved. Due to this, the CSSC performance showed significant improvement as semiconductor sensitised cathodic solar cells (CSSC). The IPCE and photocurrent density of the CSSC achieved in this study was around (19 and 7 %) and (1 and 0.5 mAcm-2) for the CuI/Cu2S and NiO/Cu2S electrodes respectively. Finally, the SS-CSSC has been fabricated by employing n-Fe2O3 electron transport layer. The construction of SS-CSSC for the first time using the n-Fe2O3 electron transport layer (CuI/Cu2S/Fe2O3 and NiO/Cu2S/Fe2O3) allowed us to study the materials, optical and photoelectrochemical properties of this device. Under AM 1.5 illumination, the SS-CSSC shows a photocurrent density of 6 and 9 µAcm-2 for CuI/Cu2S/Fe2O3 and NiO/Cu2S/Fe2O3 solar cells, respectively. The results of this work indicated low performance for both SS-CSSC compared to CSSC results, due to the lack of adsorption between the absorber and Fe2O3 electrode. However, this study proved the concept of SS-CSSC based on semiconductor material, which is valuable for the future work of cathodic semiconductor sensitised solar cells as well as solid-state tandem solar cells.
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Sholin, Veronica. "Luminescent solar concentrators and all-inorganic nanoparticle solar cells for solar energy harvesting /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2008. http://uclibs.org/PID/11984.
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Mathiazhagan, Gayathri [Verfasser], and Stefan [Akademischer Betreuer] Glunz. "Interfacial analysis of perovskite solar cells using sub-cells." Freiburg : Universität, 2020. http://d-nb.info/1221523961/34.
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Slade, Alexander Mason Electrical Engineering UNSW. "Boron tribromide sourced boron diffusions for silicon solar cells." Awarded by:University of New South Wales. Electrical Engineering, 2005. http://handle.unsw.edu.au/1959.4/21850.
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This thesis undertakes the development, characterization and optimization of boron diffusion for silicon solar cells. Heavy diffusions (sheet resistance < 40 Ohm/square) to form a back surface field, and light diffusions (sheet resistance > 100 Ohm/square) to form oxide-passivated emitters were developed. Test structures and solar cells were fabricated to assess uniformity, lifetime and recombination effects due to the light and heavy boron diffusions. It was found that the growth of a thin ~200 ??, thermal oxide, during stabilization ??? immediately prior to the boron diffusion - was required to maintain high lifetime and reduce surface recombination (reducing the emitter saturation current density) for all boron diffusions. The heavy boron diffusion process was incorporated into the single side buried contact solar cell processing sequence. The solar cells fabricated had both boron diffused and Al/Si alloyed P+ regions for comparison. This research conclusively showed that boron diffused solar cells had significantly higher open circuit voltage compared to Al/Si alloyed devices. Fabrication of n-type solar cells, and their subsequent characterization by overlayed secondary electron image and the electron beam induced current map showed that the Al/Si alloy varied in depth from 5 to 25 micrometers deep. Methodology and characterization for light, oxide-passivated boron diffusions are also presented. This study yielded boron diffused emitters (sheet resistance > 100 Ohm/square) with low emitter saturation current. It was observed that this was possible only when the thermal oxidation after the boron diffusion was minimal, less than 1,000 ??. This was due to the segregation effect of boron with oxide, decreasing the surface concentration that in turn decreased the electric field repulsion of electrons from the surface. Device modelling of n-type solar cells is presented where the parameters of the modelling include the results of the light, oxide-passivated boron diffusions. This modelling shows n-type-base material with light oxide-passivated boron diffusion has higher potential conversion efficiency than forming a solar cell from phosphorous diffused p-type material.
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Timmreck, Ronny. "Characterization of tandem organic solar cells." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-183130.
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The tandem solar cell concept is a promising approach to improve the efficiency of photovoltaic devices. However, characterization of tandem solar cell devices is challenging since correct efficiency determination demands special experimental infrastructure as well as suitable characterization procedures. Even though the appropriate IEC and ASTM measurement standards define all that very precisely, they cannot be applied without special care to organic photovoltaics (OPV) because they were originally developed for inorganic devices. As a consequence, nowadays almost all tandem organic solar cell publications are not using correct characterization procedures, often resulting in questionable efficiency values.
The aim of this work is developing a measurement procedure for tandem organic solar cells assuring their correct characterization. Therefore, at first the existing standards and measurement procedures for tandem solar cells are reviewed and challenges when applying these standards to organic solar cells are identified. As main challenges the relatively low fill factors and distinct nonlinearities of organic solar cells are identified.
As preliminary experiments, single junction organic solar cells are investigated to analyze the influence of measurement parameters like bias irradiance, bias voltage, and chopper frequency on the external quantum efficiency (EQE) of organic solar cells. This results in parameter sets assuring minimized artifacts for the subsequent EQE determination of the subcells of tandem organic solar cells.
The main part of this thesis presents the detailed characterization of a tandem OPV example device. First, EQE is measured and validated by two independent institutes. The EQE results are used to calculate the illumination conditions to reach AM1.5g conditions for both subcells with a multi-source sun simulator. The resulting efficiency value under standard reporting conditions (SRC) is found to be 5% lower than the efficiency measured with a single-source sun simulator. A full spectrometric characterization shows that differing fill factors of the subcells are the reason for this behavior.
To overcome the main reason for the complicated measurement procedure of tandem solar cells, the inaccessibility of the individual subcells, three different approaches for the jV-characteristics determination of the subcells are presented. The so-called Bias Voltage Approach is based on EQE-measurements under varying bias voltage and needs no additional electrical contacts. Therefore, it can be applied to existing devices. The Voltage Contact Approach as well as the Current Contact Approach require in changed stack designs. Therefore, they cannot be applied to existing devices but give more accurate results.
Finally, a procedure for characterizing tandem organic solar cells is formulated. This procedures aims at giving practical advice how to characterize tandem organic solar cells to achieve results conforming to the measurement standards and being as accurate and reproducible as possible. Hence, this thesis attempts to establish standards for a correct measurement of tandem organic solar cells of which other emerging solar cell technologies can profit as well.
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Schumacher, Jürgen Otto. "Numerical simulation of silicon solar cells with novel cell structures." [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9170598.
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Reusswig, Philip David. "Sensitized energy transfer for organic solar cells, optical solar concentrators, and solar pumped lasers." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93831.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 123-130).
The separation of chromophore absorption and excitonic processes, such as singlet exciton fission and photoluminescence, offers several advantages to the design of organic solar cells and luminescent solar concentrators (LSCs) for the end goal of achieving a lower cost solar energy generation. This thesis explores three new device architectures to overcome limited solar absorption in singlet-exciton-fission based solar cells and neodymium based LSCs. The process of singlet exciton fission is de-coupled from photon absorption, exciton diffusion, and charge transport in singlet-exciton-fission based solar cells by inserting a singlet fission material at the donor-acceptor interface of an organic solar cell. Singlet excitons generated in the singlet exciton donor are transferred to the singlet fission material through near field energy transfer. In this device structure, the singlet donor can be chosen for high photon absorption, exciton diffusion, and charge transport, and the singlet fission sensitizer can be selected for high singlet fission efficiency. We demonstrated a doubling of the external quantum efficiency from 12.8% to 27.6% in a singlet donor (TPTPA) through the introduction of thin film singlet fission sensitizer (rubrene) for high efficiency organic solar cells. To reduce the cost of electricity generated by sunlight via LSC systems, replacing the expensive high efficiency visible photovoltaic (PV) elements with cheap, high efficiency, earth abundant near-infrared PV elements made with silicon. This requires replacing within the LSC the visible emitting chromophores with near infrared emitters. Here, we present the use of a lanthanide ion, neodymium--colloidal nanocrystal energy cascade system as a promising LSC emitter scheme for the silicon spectral region. Peak optical quantum efficiencies of 43% in a Nd³+:glass based LSC are demonstrated with simulated high geometric gain performance. With cascade energy transfer, the optical quantum efficiency in the visible of a Nd³+:glass is significantly improved with peak efficiency of 28%. The enhanced solar absorption of Nd³+:glass through cascade energy transfer can be extended into the infrared with more optimal sensitizers. The idea of directly converting broad-band solar radiation into coherent and narrow-band laser radiation could enable many attractive technologies for solar energy. Here, we present an architecture for solar pumped lasers that uses a luminescent solar concentrator to decouple the conventional trade-off between solar absorption efficiency and the mode volume of the optical gain material. We report a 750-[mu]m-thick Nd³+-doped YAG planar waveguide sensitized by a luminescent CdSe/CdZnS (core/shell) colloidal nanocrystal, yielding a peak cascade energy transfer of 14%, a broad spectral response in the visible portion of the solar spectrum, and an equivalent quasi-CW solar lasing threshold of 20 W-cm2 , or approximately 200 suns. The efficient coupling of incoherent, spectrally broad sunlight in small gain volumes should allow the generation of coherent laser light from intensities of less than 100 suns.
by Philip David Reusswig.
Ph. D.
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Marín, Beloqui José Manuel. "Solution processed inorganic semiconductor solar cells." Doctoral thesis, Universitat Rovira i Virgili, 2015. http://hdl.handle.net/10803/334407.
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En aquesta tesi, l'estudi optoelectrònica i fabricació de diferents solució de processament de semiconductors inorgànics com ara PBS Quantum Dots i cèl·lules solars perovskita s'han fabricat. Al llarg d'aquesta tesi mesuraments optoelectrònics com fotoinducidas càrrega Extracció (PICE), fotoinducidas transitòria fotovoltaje (PIT-PV), fotoinducidas transitòria fotocorriente (PIT-PC) Laser transitòria Espectroscòpia d'Absorció (L-TAS) s'han realitzat a les cèl·lules solars eficients per tal de estudiar els diferents processos elèctrics interns presents en el dispositiu sota condicions de treball.
Usant aquestes tècniques, el desdoblament dels nivells de Fermi s'han trobat per ser l'origen de la tensió en PBS QD cèl·lules solars (Capítol 2).
A més, en el capítol 4.1 d'un estudi optoelectrònic intensiva s'ha realitzat a les cèl·lules solars perovskita mesoporosos, on es van descobrir decaïments biexponenciales de TPV i càrrega diferencial es va proposar manera tan adequada per obtenir la càrrega generada en el dispositiu.
D'altra banda, els dispositius van ser fabricats utilitzant diferents polímers com HTM, i els resultats proporcionats van confirmar que la regeneració va ser superior al 90%, i que PIT-PV realitzat en condicions de foscor corresponen a la recombinació entre els orificis de la HTM i els electrons en el TiO2, com presentat en el capítol 4.2.
A més, els resultats presentats en el capítol 4.3 mostrar que una capa de Al2O3 monoatòmic alentir el recombinació en el dispositiu d'augment de la tensió del dispositiu.En esta tesis, el estudio optoelectrónico y la fabricación de diferentes solución de procesado de semiconductores inorgánicos tales como PbS Quantum Dots y células solares de perovskita se han fabricado. A lo largo de esta tesis medidas optoelectrónicos como fotoinducidas carga Extracción (PICE), fotoinducidas transitoria fotovoltaje (PIT-PV), fotoinducidas transitoria fotocorriente (PIT-PC) Laser transitoria Espectroscopia de Absorción (L-TAS) se han realizado a las células solares eficientes con el fin de estudiar los diferentes procesos eléctricos internos presentes en el dispositivo bajo condiciones de trabajo. Usando estas técnicas, el desdoblamiento de los niveles de Fermi ha sido encontrado como el origen de la tensión en PbS QD células solares (Capítulo 2). Además, en el capítulo 4.1 de un estudio optoelectrónico intensiva se ha realizado a las células solares perovskita mesoporosos, donde se descubrieron decaimientos biexponenciales de TPV y carga diferencial se propuso manera tan adecuada para obtener la carga generada en el dispositivo. Por otra parte, los dispositivos fueron fabricados utilizando diferentes polímeros como HTM, y los resultados proporcionados confirmaron que la regeneración fue superior al 90%, y que PIT-PV realizado en condiciones de oscuridad corresponden a la recombinación entre los huecos de la HTM y los electrones en el TiO2, como presentado en el capítulo 4.2. También, los resultados presentados en el capítulo 4.3 mostraron que una capa de Al2O3 monoatómico ralentiza la recombinación en el dispositivo de aumento de la tensión del dispositivo.
In this thesis, the optoelectronic study and fabrication of different solution processed inorganic semiconductor such as PbS Quantum Dots and perovskite solar cells have been fabricated. Along this thesis optoelectronic measurements such as PhotoInduced Charge Extraction (PICE), PhotoInduced Transient PhotoVoltage (PIT-PV), PhotoInduced Transient PhotoCurrent (PIT-PC) Laser Transient Absorption Spectroscopy (L-TAS) have been performed to efficient solar cells in order to study the different inner electrical processes present in the device under working conditions. Using these techniques, the splitting of Fermi levels have found to be the origin of the voltage in PbS QD solar cells (Chapter 2). Besides, in chapter 4.1 an intensive optoelectronic study has been performed to mesoporous perovskite solar cells, where biexponential decays of TPV were discovered and Differential Charging was proposed as suitable way to obtain the charge generated in the device. Moreover, devices were fabricated using different polymers as HTM, and results provided confirmed that the regeneration was over 90%, and that PIT-PV performed in dark conditions correspond to the recombination between the holes in the HTM and the electrons in the TiO2, as presented in chapter 4.2. Also, results presented in chapter 4.3 showed that a monoatomic layer of Al2O3 slow down the recombination in the device increasing the device voltage..
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Kvanes, Kirsti. "Modeling of intermediate band solar cells." Thesis, Norwegian University of Science and Technology, Department of Physics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-6348.
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