NdCl Dose as a Universal Approach for High-Efficiency Perovskite Solar Cells Based on Low-Temperature-Processed SnO.

The defects on the surface of low-temperature-processed electronic transport layers hindered the development of efficient flexible perovskite solar cells. Herein, we develop a universal NdCl dosing strategy to circumvent the residual Sn(II)-OH defects from the incomplete wet-chemical reaction. The introduction of NdCl does not lead to the doping of Nd ions but rather the formation of a composite film of NdCl with SnO. The dose of NdCl effectively reduces surface trap states at low-temperature-processed SnO films, leading to increased carrier extraction and reduced carrier accumulationrecombination at the ETL/perovskite interface. These improvements result in perovskite solar cells (PvSCs) with significantly enhanced power conversion efficiency (PCE) and eliminated hysteresis. Finally, efficiencies of 18.62% and 21.49% for PvSCs based on MAPbI and FAMAPbI perovskites, respectively, were achieved on rigid substrates. The test on a flexible device based on Cs(FAMA)(IBr) perovskite realized a PCE of 16.14% and an incredible of 1.158 V. This study indicated the potential of NdCl dose as a universal approach to enhance the performance of PvSCs with low-temperature-processed SnO ETL.