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

Many recent studies have shown that perovskite solar cells (PSCs) employing SnO 2 as an electron transport layer (ETL) exhibit extremely high efficiency which is close to that of the device with the same structure using TiO 2. Considering the sensitivity of the PSC performance to the ETL/perovskite interface, interface engineering of the SnO 2 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 SnO 2 ETL as the buffer layer to modulate the SnO 2 /perovskite lattice mismatch induced interface stress, and enhanced the interface interaction between SnO 2 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% (J sc = 24.15 mA/cm2, V oc = 1.10 V, and FF = 0.78) is obtained for Cs 0.05 MA y FA 0.95-y PbI 3-x Cl x planar PSCs. • The amino acid buffer layer as the buffer layer is introduced on SnO 2 ETL. • The interface interaction between SnO 2 and perovskite is enhanced. • The buffer layer enhances the charge transfer and collection at interface. • High efficiency perovskite solar cells over 20% and good stability are achieved. [ABSTRACT FROM AUTHOR]