Ye Feihong, Ma Junjie, Chen Cong, Wang Haibing, Xu Yuhao, Zhang Shunping, Wang Ti, Tao Chen, Fang Guojia
Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education of China, School of Physics and Technology, Wuhan University, Wuhan, 430072, P. R. China.
Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou, 450001, P. R. China.
Adv Mater. 2021 Jan;33(3):e2007126. doi: 10.1002/adma.202007126. Epub 2020 Dec 9.
So far, the combination of methylammonium bromide/methylammonium chloride (MABr/MACl) or methylammonium iodide (MAI)/MACl is the most frequently used additives to stabilize formamidinium lead iodide (FAPbI ) fabricated by the sequential deposition method. However, the enlarged bandgap due to the addition of bromide and the ambiguous functions of these additives in lead iodide (PbI ) transformation are still worth considering. Herein, the roles of MACl in sequentially deposited Br-free FA-based perovskites are systematically investigated. It is found that MACl can finely regulate the PbI /FAI reaction, tune the phase transition at room temperature, and adjust intermediate-related perovskite crystallization and decomposition during thermal annealing. Compared to FAPbI , the perovskite with MACl exhibits larger grain, longer carrier lifetime, and reduced trap density. The resultant solar cell therefore achieves a champion power conversion efficiency (PCE) of 23.1% under reverse scan with a stabilized power output of 23.0%. In addition, it shows much improved photostability under 100 mW cm white illumination (xenon lamp) in nitrogen atmosphere without encapsulation.
到目前为止，溴化甲铵/氯化甲铵（MABr/MACl）或碘化甲铵（MAI）/MACl的组合是通过顺序沉积法制备甲脒碘化铅（FAPbI）时最常用的稳定剂。然而，由于添加溴化物导致的带隙增大以及这些添加剂在碘化铅（PbI）转化中的作用尚不明确，仍值得考虑。在此，系统地研究了MACl在顺序沉积的无溴FA基钙钛矿中的作用。研究发现，MACl可以精细地调节PbI/FAI反应，在室温下调整相变，并在热退火过程中调节与中间体相关的钙钛矿结晶和分解。与FAPbI相比，含有MACl的钙钛矿具有更大的晶粒、更长的载流子寿命和更低的陷阱密度。因此，所得的太阳能电池在反向扫描下的最高功率转换效率（PCE）为23.1%，稳定功率输出为23.0%。此外，在氮气气氛中、无封装的情况下，该电池在100 mW cm白色光照（氙灯）下表现出显著提高的光稳定性。
