Enhanced efficiency and stability of planar perovskite solar cells by introducing amino acid to SnO2/perovskite interface

Abstract Many recent studies have shown that perovskite solar cells (PSCs) employing SnO2 as an electron transport layer (ETL) exhibit extremely high efficiency which is close to that of the device with the same structure using TiO2. Considering the sensitivity of the PSC performance to the ETL/perovskite interface, interface engineering of the SnO2 electron transport layer helps to further release the potential of planar structure PSCs and promote their commercialization. Herein, we introduce an amino acid self-assembled layer onto the SnO2 ETL as the buffer layer to modulate the SnO2/perovskite lattice mismatch induced interface stress, and enhanced the interface interaction between SnO2 and perovskite caused by hydrogen-bonding and/or electrostatic interactions between the amino groups and the perovskites framework. Due to the improved perovskite film quality and enhanced interface charge transfer/extraction, a champion efficiency of 20.68% (Jsc = 24.15 mA/cm2, Voc = 1.10 V, and FF = 0.78) is obtained for Cs0.05MAyFA0.95-yPbI3-xClx planar PSCs.