High efficiency planar-type perovskite solar cells with negligible hysteresis using EDTA-complexed SnO<sub>2</sub>.

Yang, Dong; Yang, Ruixia; Wang, Kai; Wu, Congcong; Zhu, Xuejie; Feng, Jiangshan; Ren, Xiaodong; Fang, Guojia et al. · Nat Commun · 2018

basic_science · Level V

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Abstract

Even though the mesoporous-type perovskite solar cell (PSC) is known for high efficiency, its planar-type counterpart exhibits lower efficiency and hysteretic response. Herein, we report success in suppressing hysteresis and record efficiency for planar-type devices using EDTA-complexed tin oxide (SnO<sub>2</sub>) electron-transport layer. The Fermi level of EDTA-complexed SnO<sub>2</sub> is better matched with the conduction band of perovskite, leading to high open-circuit voltage. Its electron mobility is about three times larger than that of the SnO<sub>2</sub>. The record power conversion efficiency of planar-type PSCs with EDTA-complexed SnO<sub>2</sub> increases to 21.60% (certified at 21.52% by Newport) with negligible hysteresis. Meanwhile, the low-temperature processed EDTA-complexed SnO<sub>2</sub> enables 18.28% efficiency for a flexible device. Moreover, the unsealed PSCs with EDTA-complexed SnO<sub>2</sub> degrade only by 8% exposed in an ambient atmosphere after 2880 h, and only by 14% after 120 h under irradiation at 100 mW cm<sup>-2</sup>.