Hysteresis-Free and Efficient Perovskite Solar Cells Using SnO2 with Self-assembly L-Cysteine Layer
Abstract
Perovskite solar cells (PSCs) with SnO2 electron transport layer (ETL) still face the challenge of low efficiency with serious hysteresis due to the nonradiative recombination at the SnO2/perovskite interface. Herein, a self-assembly modification layer with multifunctional properties using L-Cysteine (Cys) is applied to solve the above issues. Through applying this novel self-monolayer between SnO2 and perovskite film, the trap state is greatly alleviated as well with an enhanced charge extraction. In addition, the naked -NH2 and sulfur atom of this monolayer will affect the crystallization dynamics of perovskite film, resulting in an improved film quality. Compared with the control device with a PCE of 18.55%, the monolayer contacts engineered device shows a significantly increase PCE over 21% along with negligible hysteresis. More interestingly, monolayer contacts engineered PSCs exhibit superior stability that over 90% of its initial PCE remains after stored at 50% relative humidity for 50 days. This work provides a promising method to fabricate planar n-i-p perovskite devices with high efficiency, stability, and repeatability.