Ji Chao, Liang Chunjun, Zhang Huimin, Sun Mengjie, Song Qi, Sun Fulin, Feng Xiaona, Liu Ning, Gong Hongkang, Li Dan, You Fangtian, He Zhiqun
Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Science, Beijing Jiaotong University, Beijing 100044, China.
ACS Appl Mater Interfaces. 2020 Apr 29;12(17):20026-20034. doi: 10.1021/acsami.9b23468. Epub 2020 Apr 15.
The grain boundaries of perovskite polycrystalline are regarded as a defect region that not only provides carrier recombination sites but also introduces device degradation pathways. Efforts to enlarging the grain size of a perovskite film and reducing its grain boundary are crucial for highly efficient and stable perovskite solar cells (PSCs). Some effective methods that facilitate grain growth are postdeposition thermal annealing and solvent vapor annealing. However, a detailed understanding of grain growth mechanisms in perovskite films is lacking. In this study, perovskite films were prepared by adding ethylamine hydrochloride (EACl) to the precursor solution. This additive strategy promotes a new grain growth mode, secondary grain growth, in perovskite films. Secondary grain growth leads to much larger grains with a high crystallographic orientation. These excellent properties lead to reduced grain boundaries and the densities of boundary defects. The improved film quality results in a prolonged charge-carrier lifetime and a significantly enhanced power conversion efficiency (PCE). Compared with the 18.42% PCE of the control device, the PCE of the device with EACl additives reaches 21.07%.
钙钛矿多晶体的晶界被视为一个缺陷区域，它不仅提供了载流子复合位点，还引入了器件退化途径。扩大钙钛矿薄膜的晶粒尺寸并减少其晶界，对于高效稳定的钙钛矿太阳能电池（PSC）至关重要。一些促进晶粒生长的有效方法是沉积后退火和溶剂蒸汽退火。然而，目前缺乏对钙钛矿薄膜中晶粒生长机制的详细了解。在本研究中，通过向前驱体溶液中添加盐酸乙胺（EACl）来制备钙钛矿薄膜。这种添加剂策略促进了钙钛矿薄膜中一种新的晶粒生长模式——二次晶粒生长。二次晶粒生长导致形成具有高结晶取向的更大晶粒。这些优异的性能导致晶界和边界缺陷密度降低。薄膜质量的改善导致电荷载流子寿命延长，功率转换效率（PCE）显著提高。与对照器件18.42%的PCE相比，添加EACl的器件的PCE达到了21.07%。
