新型有机-无机复合钙钛矿结构晶体生长及其性能研究

The hybrid organic-inorganic perovskite materials have attracted great attention due to their excellent optoelectronic properties, such as photoconductivity, conductivity and luminescence. The champion power conversion efficiencies (PCEs) based on hybrid perovskite materials have reached over 22.1 %. However, the toxicity of Pb and the instability of hybrid perovskite materials are the two key issues to hinder the development in the application of photoelectric field. The preparation of high quality single crystals and the characterization of intrinsic properties of hybrid organic-inorganic perovskite materials are the best way to solve these problems. The purposes of this project are to investigate growth and the physic properties of the novel hybrid perovskite materials. The main focus of the proposal is centered into four key aspects: ① The novel hybrid perovskite materials with mixed organic cation, mixed metal cation and mixed halogen anion will be designed, and the large crystals with high quality will be grown by solution method. ② The influence of structure and component on the stability of the crystals will be systematically investigated for unveiling the origin of the instability for hybrid perovskite materials. ③ The gas induced phase-changes for single crystals and the healing process of photoelectric devices will be thoroughly studied，to open a new route to design new hybrid perovskite crystals. ④Based on some of these single crystals, the thermal, optical, ferroelectric properties, especially the semiconducting properties will be characterized. This project aims to obtain the intrinsic properties, and make progress in solving the problems of instability and non-environmental friendly of Pb based materials.

有机-无机复合钙钛矿材料具有优异的光导、电导、发光等光电性能，成为目前材料研究领域的热点之一。虽然钙钛矿太阳能电池的转换效率已高达22.1%，但是材料的不稳定性和Pb的毒性仍是影响其应用的关键问题。高质量单晶的制备及本征性能的表征是解决上述问题的基础。本项目拟开展新型有机-无机复合钙钛矿晶体的生长及性能研究：①通过混合阴、阳离子等设计出多种新型化合物，并探索其晶体生长工艺，制备出一系列的高质量的单晶材料。②深入研究晶体结构和成分对材料稳定性的影响规律，探索影响稳定性的本源，制备出系列高稳定性的无Pb或少Pb的单晶材料。③探索新型气体诱导单晶相转变的工艺和机理，开辟制备复合单晶的新途征。④表征晶体的热学、光学、半导体性能等本征物理性质。本项目的开展有助于解决新型高效有机-无机复合钙钛矿材料的不稳定性及环境非友好问题。

有机-无机杂化钙钛矿材料在太阳能电池、光电探测器、LED等光电领域表现出了无可比拟的应用潜力，引起了全世界的关注。此外，这类材料可以采用溶液法在较低的温度下制备，成本低。它们已成为一种廉价、高效的新型太阳能电池材料。从 2009年至今短短六年多时间，其光电转换效率已经从最初的3.8% 提高到22.1% 以上。近年来，有机-无机复合钙钛矿材料引起了世界上各国研究人员的极大的兴趣，已成为材料研究领域的热点之一。.目前限制有机无机 复合钙钛矿材料广泛应用的主要问题也非常明确：一是这类材料对温度、湿度和光照等较为敏感，不能长时间保持结构、组分和性能上的稳定性。二是这类材料大多含有Pb 元素，在大面积的太阳能电池板和发光器件的应用中，Pb 的毒性对环境的危害不容小觑。针对此问题，我们开展了钙钛矿晶体材料的生长、物理性能表征以及稳定性机理和无Pb化的研究，探索新型高效有机-无机复合钙钛矿结构材料，解决其在空气中的不稳定性和环境非友好的问题。.本项目针对新型含铅有机-无机复合钙钛矿晶体的分子设计及晶体生长，力求解决其稳定性、环境友好等问题，重点完成了有机-无机复合钙钛矿分子设计、晶体生长、晶体稳定性、器件制备以及性能表征等研究内容；突破了单晶生长以及单晶器件优化制备等关键技术；通过分子设计制备合成了一系列高稳定性新型低维钙钛矿材料，对其性能与结构之间的关系进行了探索；进行了大尺寸、高质量Cs3Bi2Br9单晶生长，并研制了Cs3Bi2Br9晶体(1 ̅20)晶面垂直结构和平行结构器件，在100 V的电压下，平行结构器件的X射线探测灵敏度为181 μC Gy−1 cm−2；采用控温控速反溶剂扩散法生长了高质量、大尺寸MAPbBr3单晶，对其物理性质各向异性进行了研究。