锡基钙钛矿薄膜的微结构调控与电致发光性能研究

Metal halide perovskites have shown great potential in the field of high performance and low cost lighting and display, due to their high photoluminescence quantum efficiency, good color purity and solution processability. However, the commercialization of perovskite light-emitting diodes (LEDs) is seriously hindered by the toxicity of traditional lead-based perovskites. Previous research of the applicant shows that, the multiple quantum well (MQW)-structured tin-based perovskites are promising candidates for achieving high performance lead-free perovskite LEDs due to their excellent optoelectronic properties, good film formability, and good stability. Nevertheless, due to the short research period, it is insufficient for understanding how to further improve the performance of tin-based perovskite LEDs. Investigation on the relationship between the microstructure of tin-based perovskite MQW films and the performance of perovskite LEDs is especially lacking. Therefore, this proposal will reveal the regulation rule of the microstructure (such as morphology and defect) of tin-based perovskite MQW films through investigating the crystallization process. The influence of the microstructure of tin-based perovskite MQW films on the processes of carrier injection, transport and recombination will be investigated. The relationship between the microstructure of tin-based perovskite MQW films, the carrier dynamics, and the LED performances will be clarified, which will provide new ideas for achieving high performance tin-based perovskite LEDs. The successful completion of this project is not only important for the development of tin-based perovskite LEDs, but also instructive and meaningful for the development of lead-free perovskite in other fields.

金属卤化物钙钛矿具有荧光量子效率高、色纯度好和可溶液加工等优点，在高性能、低成本发光显示领域展现出巨大潜力，但传统铅基钙钛矿的毒性严重制约了钙钛矿发光二极管（LED）的商业化。申请人前期研究发现，多量子阱结构的锡基钙钛矿具有光电性质优异、成膜性和稳定性较好等优势，有望实现高性能无铅钙钛矿LED。但由于研究时间较短，对如何进一步提高锡基钙钛矿LED性能的认识尚显不足，尤其缺乏锡基钙钛矿多量子阱薄膜微结构与LED性能之间关系的研究。鉴于此，本项目拟通过研究锡基钙钛矿多量子阱的结晶过程，揭示薄膜形貌和缺陷等微观结构的调控规律；通过研究多量子阱薄膜微结构对载流子注入、输运和复合过程的影响，阐明薄膜微结构、载流子动力学和LED性能之间的内在关系，为实现高性能锡基钙钛矿LED提供新思路。本项目的顺利实施，不仅对锡基钙钛矿LED的发展意义重大，而且对钙钛矿在其他领域的无铅化发展也具有指导意义。

显示与照明是国民经济的战略性支柱产业，开发高性能、低成本的新型发光材料与器件是推动该产业快速发展的关键。相比于传统的无机和有机半导体发光材料，金属卤化物钙钛矿具有荧光量子效率高、载流子迁移率高、缺陷容忍度高、低温可溶液加工等优势，有望实现兼具无机和有机发光器件（LED）优点的新型发光技术，在低成本、大面积、高亮度、柔性显示与发光领域具有重要的研究价值和经济价值。经过几年的发展，钙钛矿LED器件的外量子效率已逐渐接近商业化的有机LED。但是，该领域仍存在一些尚未解决的关键性难题。首先，溶液法制备的钙钛矿在制备过程中原位结晶生长的机理尚不清晰；其次，高效率钙钛矿LED中的铅元素严重制约了其商业化发展。针对上述问题，首先，我们通过改变前驱体溶液组分和添加剂种类，揭示了具有优异光电性能的多量子阱钙钛矿中，量子阱阱宽分布的形成机制和化学根源；阐明了添加剂分子上的有机功能团对钙钛矿结晶取向和缺陷钝化的调控机理，分别获得了高效率的绿光（10.8%）和近红外（22.2%）钙钛矿LED。其次，我们开发了一种制备高质量锡基无铅钙钛矿发光薄膜和器件的普适性方法，即通过调控薄膜旋涂过程中的溶剂氛围，实现薄膜的原位重结晶和二次生长，从而减少缺陷态，获得了外量子效率达5.3%的高效锡基钙钛矿LED。该项目的实施积极推动了我国在钙钛矿发光领域的快速发展。已发表包括Nature Communications和Advanced Materials在内的SCI论文4篇，申请中国发明专利2项，培养硕士研究生4人。