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

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

Research output: Contribution to journalArticlepeer-review


Mixtures of cations or halides with FAPbI 3 (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-FAPbI 3 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-FAPbI 3 below the thermodynamic phase-transition temperature. We used these low-defect-density α-FAPbI 3 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.

Original languageEnglish (US)
Article numbereabb8985
Issue number6512
StatePublished - Oct 2 2020

ASJC Scopus subject areas

  • General


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