共轭有机元对杂化钙钛矿基异质结太阳能电池性能的影响机制

The properties of organic-inorganic hybrid perovskite crystalline are closely related to the composition and structure of organic and .inorganic components. Comparing to the inorganics, the organics are more various, thus have wider rang of choices. The internal bonding state, band structure, as well as the electronic properties of the hybrid perovskite are affected significantly by different species and structure of the organics. This project will focus on the hybrid perovskites which have different conjugated organics. Fluorescence spectroscopy, femtosecond transient optical spectra and in-situ photoluminescence-quenching measurements are introduced to investigate the quantum well structure, electron-hole diffusion lengths and lifetime. Solid heterojunction solar cells are assembled based on these hybrid perovskites, and the relationship between crystal properties and photoelectric transformation efficiency is also analyzed, in order to reveal the influence mechanism of crystal structure and electronic properties on devices performance, and determine the crystal structure which is benefit to improving the device function. This project clarifies the fundamental photophysical mechanisms according to the photoinduced intra-crystal charge separation and transfer. Moreover, it will not only provide new ideas for design and synthesis of complex organic components based hybrid perovskite whit excellent photo electronic properties, but also lay a theoretical and experimental foundation for construction of the novel and optimized all-solid state organic-inorganic hybrid perovskite based heterojunction solar cells.

有机-无机杂化钙钛矿晶体的性能与有机元和无机元的组成与结构密切相关。而有机元比无机元更加丰富多样，选择范围更大。有机元的种类和结构的改变会影响整个杂化钙钛矿晶体的内部结合状态、能带结构和电子特性。本项目以含不同共轭有机元的杂化钙钛矿结构晶体为对象：利用荧光光谱，飞秒级瞬态吸收光谱和原位光致发光淬灭等技术分别研究其量子阱结构，载流子的扩散长度和寿命；组装基于这类材料的全固态杂化钙钛矿基太阳能电池，探究共轭有机元与杂化钙钛矿的性质及其太阳能电池的光电转化效率的关系；揭示晶体结构和电子特性对太阳能电池性能的影响机制，确定能改善器件性能的材料结构。本项目从晶体内部的光生电荷分离和转移来阐明含共轭有机元的杂化钙钛矿的光物理机理，为设计与合成具有良好的光电性能的，含复杂有机元的杂化钙钛矿材料提供新的思路，并为构筑新型高性能、低温可溶液加工的全固态有机-无机钙钛矿异质结太阳能电池提供理论和实验基础。

我们构筑了基于甲胺阳离子和共轭结构的甲脒阳离子的混合阳离子钙钛矿电池，以提高太阳能光的利用率。调整前驱体中两种阳离子的比例得到具有最佳带隙的钙钛矿材料。通过反溶剂法控制薄膜的结晶过程，得到高质量的钙钛矿薄膜。研究表明基于MA0.6FA0.4PbI3型钙钛矿的器件的最优效率达到10.55%。在此基础上制备了基于TiO2/ZrO2双框架结构的PSCs器件。研究了ZrO2薄膜的厚度对器件性能的影响。研究表明当ZrO2薄膜的厚度为167nm时，器件最优效率为11.33%。通过原子层沉积技术制备了不同厚度的，均匀、无针孔缺陷的TiO2致密层薄膜。研究了TiO2薄膜的厚度对器件性能的影响。结果表明这些影响主要与表面粗糙度、透过率，电荷转移电阻、电子空穴复合几率及载流子寿命有关。基于2000循环得到的TiO2致密层薄膜的PSCs器件的效率最优为7.82%。此外器件在常规环境中保存1个月后，仍能保持最初效率的96%，具有良好的稳定性。我们采用TiO2陶瓷靶材和磁控溅射技术制备了TiO2致密层。探讨了不同厚度的TiO2致密层对PSCs性能的影响，得出当TiO2致密层厚度为94nm，器件性能最优为9.73%。通过水热合成法在不同反应时间下制备了一系列长度的金红石型TiO2 纳米棒阵列薄膜。研究了金红石型TiO2 纳米棒阵列薄膜的厚度对器件性能的影响，得出当TiO2 纳米棒阵列薄膜的厚度为688nm时，TiO2 NRAs/CH3NH3PbI3/C器件效率达到最优为8.56%。