Dipolar cations confer defect tolerance in wide-bandgap metal halide perovskites

Hairen Tan, Fanglin Che, Mingyang Wei, Yicheng Zhao, Makhsud I. Saidaminov, Petar Todorović, Danny Broberg, Grant Walters, Furui Tan, Taotao Zhuang, Bin Sun, Zhiqin Liang, Haifeng Yuan, Eduard Fron, Junghwan Kim, Zhenyu Yang, Oleksandr Voznyy, Mark Asta, E. Sargent

Research output: Contribution to journalArticlepeer-review

89 Scopus citations

Abstract

Efficient wide-bandgap perovskite solar cells (PSCs) enable high-efficiency tandem photovoltaics when combined with crystalline silicon and other low-bandgap absorbers. However, wide-bandgap PSCs today exhibit performance far inferior to that of sub-1.6-eV bandgap PSCs due to their tendency to form a high density of deep traps. Here, we show that healing the deep traps in wide-bandgap perovskites—in effect, increasing the defect tolerance via cation engineering—enables further performance improvements in PSCs. We achieve a stabilized power conversion efficiency of 20.7% for 1.65-eV bandgap PSCs by incorporating dipolar cations, with a high open-circuit voltage of 1.22 V and a fill factor exceeding 80%. We also obtain a stabilized efficiency of 19.1% for 1.74-eV bandgap PSCs with a high open-circuit voltage of 1.25 V. From density functional theory calculations, we find that the presence and reorientation of the dipolar cation in mixed cation–halide perovskites heals the defects that introduce deep trap states.
Original languageEnglish (US)
JournalNature Communications
Volume9
Issue number1
DOIs
StatePublished - Aug 6 2018
Externally publishedYes

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