Vapor-assisted deposition of highly efficient, stable black-phase FAPbI3 perovskite solar cells.

Lu, Haizhou; Liu, Yuhang; Ahlawat, Paramvir; Mishra, Aditya; Tress, Wolfgang R; Eickemeyer, Felix T; Yang, Yingguo; Fu, Fan; Wang, Zaiwei; Avalos, Claudia E; Carlsen, Brian I; Agarwalla, Anand; Zhang, Xin; Li, Xiaoguo; Zhan, Yiqiang; Zakeeruddin, Shaik M; Emsley, Lyndon; Rothlisberger, Ursula; Zheng, Lirong; Hagfeldt, Anders; Grätzel, Michael

doi:10.1126/science.abb8985

Vapor-assisted deposition of highly efficient, stable black-phase FAPbI3 perovskite solar cells.

Author:

Lu, Haizhou

Liu, Yuhang ; Ahlawat, Paramvir ; Mishra, Aditya ; Tress, Wolfgang R ; Eickemeyer, Felix T ; Yang, Yingguo ; Fu, Fan ; Wang, Zaiwei ; Avalos, Claudia E ; Carlsen, Brian I ; Agarwalla, Anand ; Zhang, Xin ; Li, Xiaoguo ; Zhan, Yiqiang ; Zakeeruddin, Shaik M ; Emsley, Lyndon ; Rothlisberger, Ursula ; Zheng, Lirong ; Hagfeldt, Anders ; Grätzel, Michael

Keywords:

General Science & Technology

Abstract:

Mixtures of cations or halides with FAPbI3 (where FA is formamidinium) lead to high efficiency in perovskite solar cells (PSCs) but also to blue-shifted absorption and long-term stability issues caused by loss of volatile methylammonium (MA) and phase segregation. We report a deposition method using MA thiocyanate (MASCN) or FASCN vapor treatment to convert yellow δ-FAPbI3 perovskite films to the desired pure α-phase. NMR quantifies MA incorporation into the framework. Molecular dynamics simulations show that SCN- anions promote the formation and stabilization of α-FAPbI3 below the thermodynamic phase-transition temperature. We used these low-defect-density α-FAPbI3 films to make PSCs with >23% power-conversion efficiency and long-term operational and thermal stability, as well as a low (330 millivolts) open-circuit voltage loss and a low (0.75 volt) turn-on voltage of electroluminescence.