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1
Liška, Petr. "Optická charakterizace pokročilých nanomateriálů s vysokým laterálním rozlišením." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443725.
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Advanced nanomaterials show a significant improvement in certain physical or functional properties compared to conventional materials. Such advanced materials are, for example, lead halide perovskites (LHP). It is a group of hybrid organic-inorganic materials with a direct bandgap exhibiting unique optical properties. The high quantum efficiency of photoluminescence makes nanocrystals or thin films of LHP suitable candidates for the production of light-emitting diodes, solar cells and LCD displays. Their inexpensive and simple fabrication together with their unique optical properties makes LHP one of the most developed materials of the last decade. This diploma thesis aims to study the optical properties of CsPbBr3 perovskite nanocrystals using high lateral resolution methods. CsPbBr3 perovskite nanocrystals show intense anti-Stokes photoluminescence. These nanocrystals can emit light with a lower wavelength than that of the light that causes their photoluminescence. The nanocrystals are prepared in two different ways: by evaporation or by crystallization of the precursor in a solution of dimethylformamide. The morphology, photoluminescence properties and chemical composition of individual nanocrystals are studied. Each nanocrystal is studied individually and its size, shape, photoluminescence properties and chemical compounds are determined, which leads to a deeper understanding of the anti-Stokes photoluminescence of perovskite nanocrystals.
2
Pan, Lei. "Development of perovskite for X-ray detection and gamma-ray spectroscopy." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu161886103349645.
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Ashner, Matthew N. (Matthew Nickol). "Data-driven approach to understanding exciton-exciton interactions in CsPbBr₃ nanocrystals." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122847.
Full textAbstract:
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 105-109).
Lead halide perovskites are a rapidly developing class of materials of interest for optoelectronic applications. They have a number of desirable properties such as long carrier diffusion lengths and defect tolerance that arise from the materials' unique dielectric properties. Although much of the initial interest in lead halide perovskites was geared towards producing highly efficient solar cells from the bulk material, cubic perovskite nanocrystals are a strong candidate system for light-emitting applications. Optical gain in semiconductor nanocrystals relies on emission from biexciton or doubly excited states. Knowledge of the spectral properties of biexciton states is critical for understanding optical gain development as well as many-body interactions between charge carriers more broadly. In this thesis, we develop and demonstrate a data-driven approach to characterizing the energetics and dynamics of biexciton states in CsPbBr₃ nanocrystals using TA spectroscopy.
We then use the understanding developed using the TA data to guide experiments using other techniques and further examine the physical phenomena that influence these excited states. In Chapter 2, we describe our data-driven method in detail and demonstrate its effectiveness in extracting spectral information about CsPbBr₃ nanocrystals. The method combines the target analysis fit commonly employed in organic systems with Bayesian inference and a Markov chain Monte Carlo sampler to accurately characterize the model uncertainty and vet the model itself. In Chapter 3, we apply the analysis developed in Chapter 2 to a size-series of CsPbBr₃ nanocrystals to extract the biexciton and exciton component TA spectra as a function of nanocrystal size. We find that the exciton and biexciton spectra have distinctive shapes, in contrast with the common assumption about these spectra.
The biexciton spectra a broader and slightly blue-shifted from the exciton spectrum, and the broadening and blue-shifting both increase as the nanocrystal size decreases. We verify this with our own time-resolved photoluminescence experiments. In Chapter 4, we propose and discuss in detail the development of an experiment to verify our hypothesis for why the exciton-exciton interaction is repulsive - the effect of polaron formation. We describe the development of a femtosecond stimulated Raman spectroscopy experiment to directly observe polaron formation and the challenges of performing this technique at high repetition rate. The central goal of this thesis is to describe a more careful approach to analyzing spectroscopic data.
by Matthew N. Ashner.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering
4
Vaills, Yann. "Contribution à l'étude des transitions de phase structurales des pérovskites CsCaCl3 et CsPbCI3 par résonance paramagnétique électronique de l'ion Gd3+." Paris 6, 1986. http://www.theses.fr/1986PA066149.
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Les composés du titre synthétisés par la méthode Bridgman-Stockbaerger ont été étudiés à l'aide des sondes paramagnétiques Gd3+-S2-. Le groupe d'espace de CsCaCl3 en phase quadratique a été déterminé par diffraction RX. Détermination des paramètres des hamiltoniens de spin des sondes et interprétation dans le cadre des modèles de superposition et électrostatique. Etude des transformations de phase dans les deux composes.
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Becker, Pascal [Verfasser]. "Structural and Optoelectronic Properties, Phase Transitions, and Degradation of Semiconducting CsPbI3-Perovskite Thin-Films for Photovoltaics / Pascal Becker." Wuppertal : Universitätsbibliothek Wuppertal, 2019. http://d-nb.info/120422255X/34.
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Hsieh, Yu-Hsuan, and 謝宇軒. "Ab initio study of topological insulator of perovskite CsPbBr3 and CsPbI3." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5693032%22.&searchmode=basic.
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碩士國立中興大學
精密工程學系所
107
By using the first principle calculation, the topological insulators including perovskite structure CsPbBr3 and peroskite CsPbI3 was investigated in this work. The calculation on equi-triaxial compressive strain of bulk perovskite CsPbBr3 shows that an inverse insulator band could be observed in the CsPbBr3 as subjected to 6% strain. Meanwhile the Dirac cone feature is also confirmed at the 54th layer of perovskite CsPbBr3 under 6% strain by the surface state band calculation with the insertion of 20 Å-thick vaccum layer along [001] orientation. We can conclude that CsPbBr3 acts as a topological insulator. For bulk perovskite CsPbI3, the inverse insulator band could be obtained with 4% strain according to the calculation on equi-triaxal compressive strain. Furthermore it is showed that the magnitude of band inversion increase as the strain increases from 4% to 6%. By inserting 20 Å-thick vaccum layer along [001] orientation of CsPbI3 in the surface state band calculation, the Dirac cone feature appears at the 40th layer when 4% strain is applied. However, the Dirac cone feature could even be found within first 10 layers when the strain is increased from 4% to 6%, inducating that higher the strain is exerted to perovskite CsPbI3, the fewer film layers are required for making a topological insulator.
7
CHIANG, PEI-SHAN, and 蔣佩珊. "Study single crystal CsPbBr3 perovskite photodetector." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/uw9msp.
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碩士國立臺南大學
材料科學系碩士班
107
In recent years, perovskite materials have attracted more and more attention because they have good photoelectric properties and are inexpensive, and can be prepared at room temperature. In this study, electron beam lithography was used to implant electrostatic charges between electrodes to absorb DNA molecules. Nanoparticles and DNA were used as medium to adsorb perovskite (CsPbBr3) nanoparticles as crystal seed which then grew into a single crystal across the electrodes as a light sensor. Since the obstruction of the polycrystalline interface is avoided, the photo electron-hole pair generated when the single crystal perovskite is irradiated with light is directly transmitted to the electrodes, thereby efficiently performing high-efficiency light sensing.
8
CHEN, JHAO-CHENG, and 陳昭誠. "Flexible CsPbBr3/ZnO Nanocomposites for UV Photodetectors Applications." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/33bdm2.
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碩士國立臺北科技大學
製造科技研究所
107
In this study, we separate it to three steps, first polar ZnO thin films were used to be a buffer layer for synthesizing the second step’s one dimensional polar ZnO nanorods, then we start using these samples to be the UV photodetectors to discuss the reproducibility and stability of this sample. Lastly, spin coating CsPbBr3 perovskite quantum dots on top for UV photodetector sensing. First, polar ZnO thin films were deposited onto the p-type (100) Si and mica substrate by using Plasma Enhanced Chemical Vapor Deposition (PECVD)system. Second, utilizing the as-prepared thin films from two different substrates to synthesize ZnO nanorods by a simple hydrothermal method. Herein, we discovered the influence of the different growth time. Moreover, we used spin coaters to spin coating CsPbBr3 perovskite on top, and study these nanocomposites by using these samples as UV photodetectors then discuss the responsivity and sensitivity. According to the flexibility of mica substrate, we bend the mica substrate and discuss that with different direction of the force whether the substrate is changed and how. As a result, we successfully synthesized the vertical polar ZnO nanorods. After finishing one dimensional polar ZnO nanorods, we spin coating CsPbBr3 ¬perovskite ontop and identify these samples. After finish these nanocomposites we used platinum as top electrodes to fabricate horizontal structures of metal-semiconductor-metal (MSM) with Schottky contact behavior. As a result, the performance of ZnO-based photodetector platinum electrodes, it is showing the good reproducibility and stability after 5 times switching of UV illumination. Moreover, the sensitivity was enhanced after synthesized the nanorods structure on the polar ZnO buffer layer. For ZnO-based photodetector, the polar ZnO thin films photo gain increased by growth ZnO nanorods with 1hr growth time. What’s more, after spin coating perovskite we make the photo gain become larger and both the responsivity, to find out the self-powered ability we give 0V and still get the response. Lastly, we compare the force from the opposite direction to bend the mica substrate and found out with tensile force show good reproducibility and stability, with further 25 times bent, although the responsivity decay, we can still get a good reproducibility and stability.
9
LUO, ZHENG-MING, and 羅政銘. "Preparation and Properties of Inorganic Perovskite CsPbBr3 Solar Cells." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/x528z2.
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碩士國立臺南大學
材料科學系碩士班
107
In the face of global energy crisis and environmental pollution, environmentally friendly and renewable energy is what everyone expects, and solar energy is a good choice. Perovskite solar cells, which have been experiencing rapid development since 2009, are one of the emerging materials that scholars have paid attention to in recent years. Their material properties have high photoelectric conversion efficiency, low preparation cost and low pollution. Properties, and organic-inorganic hybrid perovskite solar cells have so far approached the photoelectric conversion efficiency level of commercially available polycrystalline silicon solar cells. However, the organic-inorganic hybrid perovskite is easy to react with water and oxygen in the atmosphere, so that the life of the organic-inorganic hybrid perovskite solar cell is short. In this study, inorganic perovskite is used as the light absorbing layer, and the preparation of inorganic perovskite solar cells was discussed, and the influence of process parameters on cell characteristics and related mechanisms were clarified. The first part is to synthesize the CsPbBr3 light absorbing layer by a multiple spin coating method modified from the two-step solution method. Different spin coating speed and spin coating times are used to control the phase composition of the perovskite light absorbing layer, and its different photoelectric properties are discussed. The second part is to discusses the effect of polydimethylsiloxane (PDMS) anti-reflection layer made from different sandpaper on the transmittance of fluorine-doped tin oide (FTO) substrate. The effect of PDMS layer on the performance of inorganic perovskite solar cells is discussed. The third part is to return to the method of making the light absorbing layer. In order to reduce the temperature of the whole process, the research uses IR irradiation instead of heat treatment to discusses the formation of perovskite layer and their photoelectric properties. The results show that the inorganic perovskite solar cell fabricated by multiple spin coating method can control the phase composition of inorganic perovskite by using different spin coating speed and number of spin coating. The best experimental parameter is 2000 rpm five times deposition of PbBr2 solution. The CsPbBr3 inorganic perovskite, which is closest to the pure phase in the product, can be obtained with an efficiency of up to 4.03%. The PDMS anti-reflective layer cast on the 240C sandpaper combined with FTO can improve light penetration and obtain the highest tranmittance. The highest penetration in the visible range is 88%, and the haze is as high as 84.24%. The photoelectric conversion efficiency of the all-inorganic perovskite perovskite solar cell is increased to 4.56% from 4.03%. At the same time, in this study the use of IR-assisted growth of all-inorganic perovskite light-absorbing layer was successful to prepare all-inorganic perovskite solar cells in a low-temperature environment below 400C, and the photoelectric conversion efficiency was up to 1.19%. The proposed IR-assisted method can help the use other low temperature substrate materials for flexible all-inorganic perovskite solar cells.
10
LIN, TANG-YU, and 林唐鈺. "The Characteristics of Hybrid Graphene-CsPbBr3 Perovskite Nanocrystals Photodetector." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/t89e5w.
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碩士國立臺南大學
材料科學系碩士班
107
Inorganic perovskite nanoparticles (CsPbBr3) have high absorbance for ultraviolet (UV), while graphene has high carrier mobility. This study combines the properties of both CsPbBr3 and graphene to produce photo-sensing device that are driven at very low voltages (0.001V) and have high responsivity. In this study, graphene was used as the electrical current channel between the two electrodes, and CsPbBr3 NCs were distributed on graphene as a UV-sensing material to make a photo-electrical sensing device. UV light of 254 nm was used as a light source in the experiment, and sensing was performed with a very small bias of 0.001 V. When the sensor is irradiated with UV light, the CsPbBr3 particles will generate a pair of photo-generated electron-holes pair, and the charge in the particles affects the carrier mobility of the graphene and also forms a gate (Gating) effect, thereby performing UV light sensing. In the research, it is found that the sensing current will increase or decrease with the different semiconductor characteristics of graphene and CsPbBr3 NCs. When sensing in a vacuum environment, the current will have a significant difference in the degree of current change due to the presence of negative ions in the bromine defect or not.
11
Hui-PingJian and 簡輝平. "Characteristics Study of Microelectronic Devices Incorporated with CsPbBr3 Quantum Dots." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ykbf7p.
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LEE, ZONG-YAN, and 李宗諺. "Synthesis and Modification of Inorganic Perovskite CsPbBr3 and Its Solar Cell Characteristics." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/736v9u.
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碩士國立臺南大學
材料科學系碩士班
106
In recent years there has been a record breakthrough in the conversion efficiency of the emerging field of perovskite solar cells (PSC), however, organic-inorganic hybrid perovskites and common transport layer materials suffer from the stability issues. In this study, all-inorganic PSCs will be fabricated without any unstable or expensive organic components. The manufacturing process can be operated under ambient conditions. The research covers the formation mechanism of all-inorganic CsPbBr3 and the control of its formation conditions, study of CsPbBr3 modification using lead iodide and PEO addition, study the planar tin dioxide to replace mesoporous titania. In the first part, the effects of concentration, temperature and isopropanol alcohol on the formation of CsPbBr3 were studied. The results of PbBr2 + CsBr two-step synthesis with different molar ratios and the resulting phases CsPbBr3, Cs4PbBr6 and CsPb2Br5 in the products were discussed. In the second part, we studied the improvement of the efficiency and related mechanism by adding lead iodide and PEO. The third part studied the possibility of preparing planar tin dioxide instead of mesoporous titanium dioxide and compared the difference in conversion efficiency and hysteresis between them. According to the results, when 1M PbBr2 + 0.06M CsBr was employed and the major phase CsPbBr3 was formed at a temperature of 50℃,and after soaking in isopropanol alcohol gave a power conversion efficiency of 2.35%. Adding lead iodide and PEO modification can effectively change the characteristics of the active layer and improve the carrier transport characteristics at the interface, so that a power conversion efficiency of 3.2% can be pbtained and the battery maintains 68% of the initial efficiency value in the ambient condition for 4056 hours. Finally, the present invention uses a simple planar tin dioxide process to successfully replace the mesoporous titanium dioxide in the fabrication of CsPbBr3 solar cells and achieves an efficiency of 1.63%.
13
Chen, Hui-Hsin, and 陳慧芯. "Influence of the Polymer Matrix on Perovskite CsPbBr3 Quantum Dots Thin Films." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/35a5a2.
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碩士國立臺北科技大學
光電工程系
106
Inorganic perovskite quantum dots (CsPbX3, X=Cl, Br, I) have the characteristics of narrow FWHM, high quantum yield, and simple synthesis methods, and the emission wavelength can be adjusted from 410 nm to 700 nm. However, the poor stability of CsPbX3 QDs under wet conditions is still considered to be a problem. To overcome this problem, we have incorporated high molecular weight polymers (PMMA) into CsPbBr3 QDs to improve their stability and maintain their excellent optical properties. In this dissertation, the solution of CsPbBr3 perovskite quantum dots was prepared by uniformly mixing Cs2CO3, PbO, TOAB powder, oleic acid, toluene and other solvents, and using a centrifuge and a vacuum pump to prepare high-quality quantum dot powders. Hexane was used as a dispersant for the quantum dot powder to complete the preparation of the quantum dot solution. Finally, a solution with different proportions of quantum dots CsPbBr3 and PMMA was prepared and discussed. In the preparation of thin films, firstly, a thin film with the structure of Glass / QD-CsPbBr3 / PMMA was fabricated in a Glove box using a well-developed quantum dot CsPbBr3 solution by changing the ratio of CsPbBr3:PMMA. Observe the differences in photoluminescence intensity, absorbance, and material properties. For the thin film and material analysis of quantum dot CsPbBr3, the analysis was performed with photoluminescence (PL), transmittance and absorbance (Transmittance/Absorbance), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The properties of optical properties, structures, and morphology were further investigated to investigate the effect of doped PMMA on perovskite CsPbBr3 quantum dots.
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CHEN, HAO-TIAN, and 陳浩田. "Perovskite CsPbBr3 quantum dots prepared by recoverd waste lead from lead-acid battery." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/u9vn33.
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碩士中華科技大學
機電光工程研究所碩士班
106
In recent years, organic perovskite quantum dot semiconductors have become an integral part of the solar field and planar light-emitting devices, and they are also indispensable. The high-efficiency perovskite quantum dots have also attracted widespread attention, and have also attracted attention in many photovoltaic fields. The important application space therefore makes the material difficult to obtain and expensive. This paper proposes the use of recycled recycling of environmental protection issues, the use of lead scraped lead batteries as the material for the production of perovskite quantum dots, and its material properties for further research and analysis. The recovery of the perovskite quantum dot CsPbBr3 was performed by recovering lead scrap from lead storage batteries. The characteristics of CsPbBr3 were analyzed using different ratios. The scanning electron microscope was used to observe the surface morphology and cross section of the film. The structure and PL optical excitation spectrum measurement system were used to analyze the optical properties. Finally, the analysis situation and influence of the dispersion solution were further discussed, and the influence and results of the recovery of the lead scrap from the lead battery to produce the perovskite quantum dot were thoroughly studied. The results show that the use of lead scrap from lead-acid batteries as a material for the production of perovskite quantum dots, CsPbBr3, can be successfully synthesized. It not only saves material, but also proves that recycling is valuable, and it is helpful for future shortages of materials and materials not easily accessible to achieve a major advantage in the future, although the efficiency is not very high, it will be purified using recycled lead in the future to achieve higher efficiency.
15
KAO, YU-TING, and 高于庭. "Propertices of MAPbI3 perovskite solar cells with gold nanoparticles doped CsPbBr3 quantum dots." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/9gs68c.
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碩士國立臺北科技大學
光電工程系
107
In this study, Au-CsPbBr3 and PEDOT:PSS were spin-coated on an etched ITO (Indium Tin Oxide) substrate using a spin coater under normal atmosphere, and then moved to a nitrogen-filled glove box, MAPbI3 was coated on ITO substrate with Au-CsPbBr3 and PEDOT:PSS thin film. Then Evaporation of C60 using a vapor deposition system to form a film, return to glove box and then carry out the MAPbI3 layer heating action to make the film more uniform, and sent back to the thermal evaportation of Ag, and finally made into a perovskite solar cell of Glass/ITO/Au-CsPbBr3/PEDOT:PSS/MAPBI3/C60/Ag, with Au-CsPbBr3 as increase light trapping into the PEDOT:PSS hole transmission layer by the nano-particles through the surface plasmon resonance, MAPbI3 as a light absorbing layer, and C60 a crts as an electron transport layer. This study is mainly to addition of nano-gold particles in QD CsPbBr3 was achieved by local surface plasmon resonance. Then applied to cell, further synthesize of QD CsPbBr3 and added nano-gold particles on the characteristics of solar cells on the tradition structure of MAPbI3. For the characteristic analysis of the components,using a field emission scanning electron microscope(SEM) to analysis morphology of the thin film, X-Ray diffractometer analyzes crystal orientation, lattice constant, and grain size changes, the Ultraviolet/visible spectrophotometer analysis of its penetration, absorption spectrum, optical excitation light measurement system to analyze the optical properties, the component part is measured by a solar simulator to measure its J-V curve to obtain its open-circuit voltage (Voc), current density (Jsc), fill factor (FF), and photoelectric conversion efficiency (EQE).
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Lin, Zi-Jun, and 林子鈞. "High-quality perovskite CsPbBr3 quantum dots thin films and applications of light-emitting diodes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9xq4jz.
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碩士國立臺北科技大學
光電工程系
106
In this study, the perovskite CsPbBr3 quantum dots was prepared by using the ultrasonic oscillation method to prepare high-quality quantum dot solution. The preparation method is simple and the yield can be provided according to requirements. The different halogens are added through the ion exchange method. Under the compound, QD-CsPbX3 quantum dot solutions of different wavelengths can be synthesized in the visible light wavelength range. In order to make the use of the perovskite quantum dots solution more widely, the QD-CsPbBr3 quantum dot solution was prepared as a thin film by spin coating and used as an active layer on the light-emitting diode device. In this study, the preparation of the film through the purification process, the synthesis of the ligand (oleic acid) is removed, the purified QD-CsPbBr3 powder as hexane (Hexane) as a dispersion solvent, coated in the device structure is Glass/ITO/PEDOT: PSS/PVK/QD-CsPbBr3/TPBI/Ag light-emitting diode transparent conductive glass, wherein PEDOT:PSS and PVK are used as the hole transport layer, QD-CsPbBr3 is used as the working layer, and TPBI is used as the electron transport Layer, Ag electrode. For material analysis of QD-CsPbBr3, scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet/visible spectrophotometer, photoluminescence (PL), time-resolved photoluminescence (TRPL), photoluminescence quantum yield ( PLQY) analysis of differences in optical properties between unpurified and purified, the devices will be discussed in the ultrasonic oscillation and general synthesis method. The light-emitting diodes are further characterized by the current density vs. voltage (J-V) and electroluminescence (EL) measurements.
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Hsu, Bing-Kuan, and 徐秉寬. "Study on luminescent properties of CsPbBr3 Nanoparticles/chlorophylls Inorganic semiconductor/organic polymer hybrids and their light-emitting applications." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/5cca7t.
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碩士國立臺灣海洋大學
光電科學研究所
106
The coupling between carriers of chlorophylls in ethanol solutions and cesium lead halide perovskites (CsPbBr₃) nanoparticles (NPs) in toluene solutions has been studied by UV-vis absorption, photoluminescence (PL) , photoluminescence excitation (PLE) and time-resolved PL (TRPL) measurements. The results of PL measurement showed the PL intensity of chlorophylls in ethanol solutions was substantially enhanced by adding CsPbBr₃ NPs. Furthermore, the TRPL results showed that the decay time of chlorophylls decreased with the additions of CsPbBr₃ NPs compared with that of the corresponding pure chlorophylls, while the decay time of added CsPbBr₃ NPs in chlorophylls mixture decreased compared with that of the corresponding pure CsPbBr₃ NPs. The phenomena can be understood by the carrier transfer from CsPbBr₃ NPs into chlorophylls excited singlet states upon the photoexcitations which is supported by the results of PLE and absorption spectra. Finally, the light-emitting applications of such inorganic semiconductor/organic polymer hybrids have been developed
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TSENG, PO-WEI, and 曾柏崴. "Effects of Different Solutions Used to Purify Perovskite CsPbBr3 Quantum Dots on Their Films and Quantum-dot Light-emitting Diodes." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3p3jps.
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碩士國立臺北科技大學
光電工程系
107
In the past few years, all-inorganic perovskite quantum dots (QDs), i.e. CsPbX3, X = Cl, Br and I, have been more popular due to its excellent optoelectronic properties and multiple application. In order to develop high-performance quantum-dot light-emitting diodes (QLEDs), the quality of QD films should be improved. Therefore, different solutions (ethyl acetate, acetone, hexane, and mix solutions) were used to purify perovskite QDs to increase the quality of QD films. In this work, our CsPbBr3 QDs, were synthesized by using hot-injection and ice-water bath methods. Then they were treated by purification processes with different solutions. The QD films were prepared by spin coater. The result shows the best performance of the devices was obtained by using the mixed ethyl acetate and hexane (3:2) solution. The PL wavelength of the best QD kept at 508 nm with (high photoluminescence quantum yield) PLQY of 99 %. On the other hand, the films prepared by the best QD became more brilliant and their PL wavelength is not shift. Surprisingly, the PLQY of the films can achieve more than 90 %. Moreover, the SEM and AFM images exhibited the surface characteristics were flatter than those synthesized using other conditions. Finally, we conclude the purification processes of QLED device play a significant role to improve quality of QD films and our results may provide an outlook for the future development of QDs and QLEDs.
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Liu, Hsiao-Hsien, and 劉驍賢. "The Study of CsPbX3 Perovskite Light Emitting Diodes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/bxrum9.
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碩士國立臺灣科技大學
化學工程系
106
In this work, we focused on the studies of cesium lead bromide (CsPbBr3) perovskite light-emitting diode (LED). In the architecture of CsPbBr3 LED, CsPbBr3 thin film can be regarded as emission layer because electrons and holes will inject into CsPbBr3 thin film for radiation recombination; otherwise, home-made zinc oxide (ZnO) nanoparticles synthesized by wet chemical reaction was employed as electron transport layer (ETL); poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and poly(N-vinylcarbazole) (PVK) were used as hole injection layer (HIL) and hole transport layer (HTL), respectively. For preparation of CsPbBr3 thin film, one-step spin coating was employed. The properties of CsPbBr3 thin film were modulated by the molar ratio of precursors and the amount of additive, poly(oxyethylene) (PEO). The optical, optoelectronic and structural analyses were conducted by UV-visible absorption spectroscopy, micro-photoluminescence (-PL) and X-ray diffraction pattern (XRD), respectively. From -PL spectrum, we could obtain the emission of CsPbBr3 thin film was around 527 nm. When CsPbBr3 thin film was assembled as LED, the current density and brightness of CsPbBr3-LED under 4.5 V bias could achieve 560.68 mA/cm2 and 0.18 cd/m2 when the molar ratio of CsBr to PbBr2 and PEO addition amount were 3 : 2 and 0.005 g, respectively. To adjust the emission wavelengths of perovskite LED, part of bromide precursor was replaced by iodide precursor. CsPbBr3-xIx thin film could be prepared by spin coating and the emission wavelengths could cover 527~690 nm. Finally, CsPbBr3-xIx thin films were assembled as LED for analyzing the performance of electroluminescences.
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YAH, YU-CHUN, and 葉育淳. "Preparation and Application of CsPbI3 Perovskite Quantum Structure." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5f6ne7.
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碩士國立臺北科技大學
光電工程系
107
In recent years, Various properties of all-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, I,) quantum dots (QDs), including high photoluminescence (PL), quantum yield (QY), size-tunable band gap, improved air stability, and narrow emission peak widths, render these materials extremely attractive for a range of potential applications, such as lasers, photodetectors, light-emitting diodes, and solar cells. In this study, the preparation of the perovskite CsPbI3 quantum structure is divided into two steps，first we synthesized CsPbI3 QDs using a hot-injection method，wherein we was prepared by uniformly mixing Cs2CO3，1-octadecene (ODE) , oleic acid(OA) and quickly injected into an 1-octadecene (ODE) solution containing PbI2, oleic acid (OA), and oleyl amine (OAm)，then we have incorporated Tri-n-octylphosphine oxide (TOPO) as an additive into CsPbI3 QDs to explore its optical properties, structures and morphologies, and other characteristics. In the preparation of fluorescent films, firstly the UV glue was added to the prepared CsPbI3 solution and stir it evenly. Then, the thin film with the structure of glass/ QD-CsPbI3: UV glue was fabricated in glove box by using a Wire Bar Coaters, by changing the ratio of QDs to UV glue, it can achieve protection QDs and expect to get better absorption. For the material and fluorescent film analysis of CsPbI3 quantum structure, Aasorbance and transmittance, photoluminescence (PL), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffractometer were performed to explore its optical properties, structure and morphology, and other characteristics.
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LIN, NIEN-CHEN, and 林念辰. "Preparation of perovskite CsPbI3 quantum dots and application for solar cells." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/2wq4fe.
Full textAbstract:
碩士國立臺北科技大學
光電工程系
106
The dissertation discusses the fabrication of QDs of perovskite CsPbI3 by adding various concentrations of TBAI compounds to the synthesis to convert CsPbBr3 to CsPbI3 through ion exchange. However, it was also found that this change was observed at the same wavelength. The light source can excite different light emission wavelengths after excitation, and red shift from the original green light band to the red light wave band. In order to further optimize the quantum dot solution, the addition of a modified ligand oleic acid (OA) was chosen to achieve longer emission wavelengths.Since in the future the process is intended to be applied to the device, the properties of the quantum dot on the thin film will be further explored, and it will be spin-coated on the ITO glass for observation. For solar cell applications, all-inorganic hybrid perovskite solar cells are used in this paper. In this paper, I use the structure of glass / ITO / PEDOT: PSS / QD-CsPbI3 / TPBI / Ag for solar cell fabrication. PEDOT : PSS, QD-CsPbI3, and TPBI are the hole transport layer, active layer, and electron transport layer, respectively. In order to understand the material properties of perovskite CsPbI3 quantum dots, field emission scanning electron microscopy (FESEM), field emission transmissive electron microscopy (FETEM), ultraviolet/visible spectroscopy, and photoluminescence (PL) were used in the paper. , to observe the surface morphology of the film, the size of the crystal phase and size, luminous wavelengths and other optical properties. The solar cells are observed and analyzed through the solar simulator J-V curve, open circuit voltage, short-circuit current, fill factor, and power conversion efficiency.
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YANG, YA-ZHU, and 楊雅筑. "Preparation of CsPbX3 Quantum Dots and the Application in White Light-Emitting Diodes." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/k8k36t.
Full textAbstract:
碩士國立虎尾科技大學
材料科學與工程系材料科學與綠色能源工程碩士班
106
With the development of technologies, white light-emitting diodes (WLEDs) have been instead incandescent and fluorescent lamps and widely used in lighting and display. In the WLED fabrication, the quantum dots (QDs) or phosphors with different colors were added. Most of the commercialize phosphors have width of full width at half maximum (FWHM) and irregular morphologies, resulting in a little bit enhancement of color gamut compared to fluorescent lamps. Therefore, all inorganic perovskite QDs (CsPbX3 X=Cl, Br, I) with narrow FWHM and high quantum yield (QY) is the first choice for the backlight materials. However, fast ion exchange between halogens and poor thermal stability are the two major shortcomings for CsPbX3 QDs. This study, we use saturated alkyl amines with different of carbon chain length to prepare perovskite QDs with controllable emission wavelengths. Moreover, the QDs were coated with silica to prevent anion exchange and enhance thermal stability for backlight applications. This study includes three major parts. The first part is controlled the emission wavelength of CsPbX3 QDs through the alkyl amines (DDA, HDA and ODA) of different carbon chain length. The results show that the smaller size and short emission wavelength of QDs can be obtained with longer carbon chain length of amine. The second part is the coating of silica on the outer layer of CsPbX3 QDs. We can find that the anion exchange between red and green QDs can be avoided after coating, and the emission intensity of G-OLA/SiO2 is obviously maintained after aging at 100 oC for one day. The emission wavelength of R-QDs have blue shift more than 90 nm, that is caused by the iodine ion dissociation after aging at atmosphere for 40 days, while the shift of the R-QDs/SiO2 are less than 20 nm. The results show that the QDs coated with silica can avoid anion exchange and enhance thermal and moisture stability. The third part discusses the characteristics of the CsPbX3 QD-based WLED. We prepare the WLED in two types. First type, mixing QDs with PMMA to form fluorescent films with different QD concentrations and thickness. Second type is that incorporate R-QD/SiO2 and G-QD/SiO2 with silicone and pumping by blue chip. The Commission International d’Eclairage (CIE) chromaticity coordinates, NTSC, and sRGB of two types of WLED are (0.31, 0.33), 119 %, 167 % and (0.33, 0.31), 109 %, 153 %, respectively. Based on the above results we can find that the carbon chain length of alkyl amines affect the particle size of QDs, resulting in the emission wavelength blue shift with increasing amines chain length. The QDs coated with silica can avoid anion exchange successfully and increase thermal and moisture stability. Moreover, a high color gamut WLEDs can be obtained.
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Wang, Cheng-Ming, and 王晟名. "Color Tuning of Light-Emitting Electrochemical Cells by Employing CsPbX3 Perovskite Color Conversion Layers." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/564xu4.
Full textAbstract:
碩士國立交通大學
照明與能源光電研究所
106
Recently, light-emitting electrochemical cells (LECs) have attracted intense attention due to solution processablility, simple device architecture and allow using air stable metals. Ionic transition metal complexes (iTMCs) can provide significantly higher device efficiencies when using in emissive layers of LECs. However, iTMCs show relative broader electroluminescence (EL) spectrum (full width at half maximum (FWHM) > 50 nm), leading to color saturation problem. Using lead halide perovskite materials, which have highly color saturation (FWHM <50 nm) can provide saturated EL. In this study, green, yellow, red and deep red color conversion layers (CCLs) based on CsPbX3 perovskites are combined with LECs based on a blue-emitting iTMC to achieve saturated EL spectrum. In addition, CCLs containing these four CsPbX3 perovskites mixed in proper ratios can be integrated with blue iTMC-LECs to obtain a white spectrum with a high color rendering index (CRI) > 90. Different colors of perovskite materials can be mixed without mutual interaction. Such CRI of white EL is among the highest reported values for white LECs. This technique is thus useful for both display and lighting applications.
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Li, Zhe-Cheng, and 李哲誠. "Synthesizing CsPbX3 Quantum Dots via Hot Injection Method and Optimizing the Process for Stability." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4k4948.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
107
In this study, a hot-injection process was used to synthesized all-inorganic perovskite cesium lead bromide quantum dots (CsPbBr3 -QDs) and dodecyldimethylammonium bromide (DDABr) molecule or water molecules were used for post-treatment. Structural analyses and optical properties measurement were used to characterize without or with post-treated CsPbBr3 ¬QDs. From analysis results, we could know that after DDAB post-treated CsPbBr3 ¬QDs could obtain photoluminescence quantum yield (PL-QY) of 91.8 % and storage in toluene for 90 days, and after H2O post-treated CsPbBr3 ¬QDs could obtain PL-QY of 91.5 % and storage in n-hexane for 60 days. In addition, for red emission CsPb(I/Br)3 QDs, manganese (Mn) was used as dopant for improving the PL-QY and stability. According to analysis results, Mn doped CsPb(I/Br)3 QDs could obtain PL-QY of 96.1 % and storage in octane for 180 days. For the stability of CsPbX3 (X=Br, I) ¬QDs, tetramethyl orthosilicate (TMOS) was used as precursor for silica shell formation enclosed on the surfaces of CsPbX3 QDs. Silica shell could be regarded as humidity and oxygen barrier layer and powder fabrication. From analysis results, we could know that the stability of CsPbX3 QDs could be improved by silica barrier layer due to reduce the influence of humidity. In the next, CsPbBr3/SiO2 and [CsPb(Br/I)3]/SiO2 powders were blended together to mix with poly (methyl methacrylate) (PMMA) as light convert layer. Combing the light convert layer with blue indium gallium nitride (InGaN) light emitting diode (LED) chip with 460 nm, CIE 1931 uniform chromaticity color space, color temperature, luminous efficiency and luminance were (0.3376, 0.3366), 5400 K, 35 lmW-1 and 1787 cdm-2 under 2.5 volt. In addition, the color gamut could achieve 128 % of NTSC standard.
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Lin, Chih-Yueh, and 林志嶽. "The study of properties of CsPbX3 perovskite quantum dots and its application in emission devices." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/9ra4t2.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
105
In this study, a room temperature process was used to synthesized all-inorganic perovskite cesium lead bromide quantum dots (CsPbBr3 ¬QDs) and structural analyses and optical measurement were used to characterize as-synthesized CsPbBr3 ¬QDs. From analysis results, we can know that the room process is suitable to synthesize CsPbBr3 ¬QDs and its quantum yield approaching 82 %. The properties of CsPbBr3 ¬QDs prepared by the room temperature process are similar to that prepared by hot injection process. Comparing to hot injection, the room temperature process is more quickly and easily and with the feasibility of mass production. In addition, we can adjust the composition and emission wavelength of CsPbBr3 ¬QDs rapidly by using anion exchange process, such as Cl- and I- ions, to obtain CsPbCl3 and CsPbI3 ¬QDs. There quantum yield approach 7.6 % and 67.7%. For the study of stability of CsPbX3 (X=Cl, Br, I) ¬QDs, CsPbBr3 and CsPbI3¬ QDs were embedded on polyhedral oligomeric silsesquioxane (POSS), carry out powder production to avoid the influence of water and oxygen for long time. The CsPbBr3-POSS and CsPbI3-POSS QDs powder were mixed together on the UV gel to form the white light converter layer and the white light could be observed under the illumination of 365 nm indium gallium nitride light-emitting diode (InGaN LED). According to analyses of CIE 1931 uniform chromaticity-scale diagram and photoluminescence spectrum, our white LED device for backlight display passed through a color filter with a NTSC value of 107 % and the gamut is (0.354, 0.334).
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Hsu, Chung-En, and 徐仲恩. "Stabilizing the cubic perovskite phase of CsPbI3 nanocrystals by using small molecules bis(trimethylsilyl)sulfide." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ztkd62.
Full textAbstract:
碩士國立臺灣師範大學
化學系
105
Perovskite nanocrystals have a good application in solar cells and light-emitting diodes because of their optical properties such as high absorption coefficient, bipolar, direct energy gap and so on, so they become one of the most popular luminescent materials , But because of its low stability in the atmosphere, resulting in its practical application of the difficulties. This study is mainly for the stability of this material. This kind of material in the atmosphere due to the intrusion of water and oxygen to its crystal disintegration, but its own high optical activity crystal phase at room temperature also, will spontaneous conversion Non-optically active crystal phase, so that it lost the value of application. In this study, the use of ligand replacement, the original oleic acid as the main ligand of the perovskite nanocrystals, replaced by small molecules of hexamethyldisilane, improved its stability in the atmosphere, from Visible light absorption spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, fluorescence emission spectroscopy, etc. The observed optical properties of perovskite nanocrystals with hexamethyldisilane as ligand Which is more stable than the perovskite nanocrystals with oleic acid as ligand, which indicates that this method enhances the stability of the optically active cubic crystal phase of perovskite nanocrystals in the atmosphere to optimize its application.
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CHEN, YI-CHIA, and 陳奕嘉. "Study of Enhanced Luminescence and Stability of Cesium Lead Halide Perovskite CsPbX3 Nanocrystals by Cu2+-Assisted Anion Exchange Reactions." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/w8qtff.
Full textAbstract:
碩士東海大學
化學系
107
All inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) have good application for optoelectronic devices such as solar cell and LEDs due to their excellent optical properties such as tunable emission wavelength, bright PL emission, and high photoluminescence quantum yield (PLQY). However, owing to its unstable crystal structure, it cannot maintain the great optical properties, and its synthesis process is too cumbersome. Here, we used a simple anion exchange reaction of CsPbCl3 perovskite NCs to obtain CsPbCl3 and CsPbBr3-xClx NCs, which treated by CuX2-OLA and CuX-OLA (X = Cl, Br), respectively. We observed that the optical properties such as PLQY and stability of CsPbCl3 and CsPbBr3-xClx treated by CuX2-OLA complex are better than those treated by CuX-OLA. Furthermore, we also used in-situ PL and in-situ XRD to investigate the mechanism of anion exchange. At the in-situ PL measurement of CsPbCl3 treated by CuCl2-OLA, we observed that the PL intensity decrease sharply when CuCl2-OLA was added, and then gradually rise again in a short time. And a similar phenomenon was also observed in the in-situ XRD measurement. Therefore, we infer that the mechanism of anion exchange involved structural destruction and recrystallization. This work is already published in The Journal of Physical Chemistry C.