open access

https://doi.org/10.14943/doctoral.k16049

https://hdl.handle.net/2115/95672

高発光効率セシウムスズハライドペロブスカイトナノ粒子の合成

英語

2024-06-28

Hokkaido University

155p.

Colloidal halide perovskite nanocrystals (NCs) have garnered substantial attention in recent years due to their excellent optoelectronic properties, which include tunable bandgaps, high photoluminescence efficiency, and substantial absorption coefficients. These attributes have propelled their widespread utilization across diverse optoelectronic applications, including lasers, light-emitting diodes, and solar cells. However, with the growing interest in using metal halide perovskite for optoelectronic devices, concerns about the toxicity of lead in lead-based halide perovskite materials make it necessary to look for lead-free alternatives. Tin halide perovskites have emerged as promising substitutes owing to their reduced toxicity and comparable perovskite-like characteristics. Nonetheless, the synthesis of high-quality colloidal CsSnX3 (X= Cl, Br, I) perovskite NCs presents a formidable challenge, impeding their widespread adoption in next-generation optoelectronic applications. This thesis delves into the synthesis mechanism and precursor chemistry governing the formation of tin halide perovskite NCs, culminating in the development of effective synthetic methodologies conducive to yielding high-quality products. Chapter 1 provides an introduction to the research background of metal halide perovskite materials, including synthetic methods for metal halide perovskites, and summarizes the effective strategies reported to enhance the optical properties of metal halide perovskite materials. Additionally, it outlines the research progress of tin-based halide perovskite NCs. Finally, it elucidates the research topic's conceptual framework. In chapter 2, the investigation focuses on elucidating the precursor chemistry involved in the hot-injection synthesis method for representative tin halide perovskite NCs, particularly CsSnI3 NCs. Through comprehensive analysis, including nuclear magnetic resonance (NMR) spectroscopy, significant insights are gleaned regarding the role of polymeric alkanoate iodides, formed as intermediate products during the reaction between tin and iodide precursors, in modulating NCs properties such as photoluminescence quantum yield (PLQY), size, morphology, and uniformity. In chapter 3, straightforward method based on ion exchange is proposed, showcasing its effectiveness in generating high-quality CsSnX3 NCs with excellent PLQY and adjustable size. CsSnI3 NCs with a remarkable PLQY of 34.4% were obtained, surpassing the previously reported maximum value of 18.4%. The controlled reaction kinetics inherent in this approach enable the synthesis of NCs with excellent size uniformity, crucial for optoelectronic applications. In chapter 4, further exploration into controlled ion exchange processes, facilitated by incorporating an additional tin source during the synthesis of CsSnI3 NCs, unveils a pathway to enhance crystal quality. This endeavor resulted in a significant enhancement of the PLQY of CsSnI3 NCs to 49.7%, accompanied by uniform size distribution. In-depth analysis, including in-situ photoluminescence (PL) and high-resolution transmission electron microscopy (HRTEM), elucidates the role of the additional tin source in accelerating the reaction rate that minimizes uncoordinated Sn and I atoms and thus boosts the PLQY of CsSnI3 NCs. Additionally, the versatility of this methods is demonstrated through the synthesis of tin halide perovskite NCs with varied halide compositions. In summary, this thesis advances the understanding of synthesis strategies for high-quality tin halide perovskite NCs, offering valuable insights into precursor chemistry, reaction mechanisms, and synthetic methodologies. The developed approaches hold immense potential for facilitating the widespread utilization of tin halide perovskite NCs in diverse optoelectronic applications, thereby propelling the evolution of next-generation optoelectronic devices.

2024-06-28

甲第16049号

博士(理学)

(主査) 教授 松井 雅樹, 教授 長谷川 靖哉, 客員教授 野口 秀典, 客員教授 白幡 直人

総合化学院（総合化学専攻）

博士論文

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