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 (SnO2) electron-transport layer. The Fermi level of EDTA-complexed SnO2 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 SnO2. The record power conversion efficiency of planar-type PSCs with EDTA-complexed SnO2 increases to 21.60% (certified at 21.52% by Newport) with negligible hysteresis. Meanwhile, the low-temperature processed EDTA-complexed SnO2 enables 18.28% efficiency for a flexible device. Moreover, the unsealed PSCs with EDTA-complexed SnO2 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−2.
Bibliographical noteFunding Information:
The authors acknowledge support from the National Key Research Program of China (2016YFA0202403), the National Natural Science Foundation of China (61604090/ 91733301), the financial support from the Institute of Critical Technology and Applied Science (ICTAS), and the Shaanxi Technical Innovation Guidance Project (2018HJCG-17). S.P. would like to acknowledge the financial support from the Air Force Office of Scientific Research (A. Sayir). S.L. would like to acknowledge the support from the National University Research Fund (GK261001009), the Innovative Research Team (IRT_14R33), the 111 Project (B14041), and the Chinese National 1000-Talent-Plan program.
© 2018, The Author(s).