open access

https://doi.org/10.14943/doctoral.k15728

https://hdl.handle.net/2115/93145

MAPbBr3ペロブスカイト微結晶の結晶サイズ、フォトルミネッセンスおよびエレクトロルミネッセンスの最適化

英語

2024-03-25

Hokkaido University

Recently, lead halide perovskites are the most attractive semiconductor materials for light-harvesting and light-emitting applications, which is attributed to their excellent properties, such as high photoluminescence quantum yield, large absorption coefficient, low formation energy, and tunable bandgap. However, there are still issues limiting its large-scale applications, like instability and efficiency roll-off. In this thesis, I mainly focus on the study of isotropic and high-quality perovskite microcrystal synthesis, light- induced ion migration and its effect on electroluminescence blinking, and time-resolved electroluminescence of MAPbBr3 microcrystals. The thesis is summarized in five chapters. In Chapter 1, I introduce the general information about halide perovskite. First, I introduce the structure of one unit cell, chemical compositions and stability factors. Following, I introduce different size halide perovskite synthesis methods, including micro-sized single crystal, nanocrystals and quantum dots. Then I introduce the characteristics of halide perovskite, including optical properties, bandgaps, charge carrier dynamics and blinking. Finally, I introduce applications of halide perovskites, especially to solar cells and light-emitting diodes. I also present my study motivation. In chapter 2, I introduce the materials, sample preparation methods and instruments I used throughout the studies. I show the synthesis the MAPbBr3 microcrystals by various methods, such as room temperature crystallization (RTC), anti-solvent vapor-assisted crystallization (AVC), inverse temperature crystallization (ITC), modified-ITC and blade-coating methods. I investigate the properties of the microcrystals using optical microscopy and fluorescence microscopy. I study the photoluminescence and electroluminescence blinking of perovskite microcrystals using single particle micro spectroscope, and the photoluminescence and electroluminescence decays by time-resolved photoluminescence and electroluminescence spectroscopy. In chapter 3, I demonstrated the synthesis of isotropic high quality MAPbBr3 microcrystals. I investigate the role of an additive N- Cyclohexyl-2-pyrrolidone and reaction temperature on the crystal size, shape, quality, and density. I also discuss the crystal nucleation mechanism and crystal growth kinetics. Finally, I expand the modified ITC method to various types of halide perovskites. In chapter 4, I investigate the light-soaking effect on the photoluminescence lifetime and electroluminescence blinking of MAPbBr3 microcrystals, the ON and OFF probability distribution of electroluminescence blinking statistics has been studied. The mechanism of light-induced halide ion migration and trap healing is correlated with the electroluminescence intensities and photoluminescence lifetime. In chapter 5, I investigate the time-resolved electroluminescence of MAPbBr3 microcrystals. First, I measure the optical spectra and electroluminescence decay of commercial blue, green and red LEDs, and confirm the instrument reliability for time-resolved electroluminescence measurements. Then, I study the photoluminescence spectra, electroluminescence, and photoluminescence decays of MAPbBr3 microcrystals. Finally, I investigate the influence of MABr treatment on electroluminescence and photoluminescence decays of MAPbBr3 microcrystals, where Br vacancies are filled. The mechanism of halide ion vacancy filling enhanced electroluminescence and photoluminescence decays increase are discussed.

2024-03-25

甲第15728号

博士(環境科学)

(主査) 教授 Biju Vasudevan Pillai, 教授 小西 克明, 准教授 髙野 勇太

環境科学院（環境物質科学専攻）

博士論文

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