Yb-doped SnO2 electron transfer layer assisting the fabrication of high-efficiency and stable perovskite solar cells in air

To date, most preparation processes of polycrystalline perovskite films still have to be performed in a glovebox filled with inert gas, limiting the application due to their high cost and complexity. In this work, we exploit a facile processing technique for the preparation of perovskite solar cells (PSCs) under ambient conditions by the Yb3+ doping effect for SnO2 electron transfer layer. This remarkable and facile interface doping strategy promotes all-air processed planar PSCs, giving enhanced power conversion efficiency (PCE) from 15.69% to 17.31% with a decreasing hysteresis effect. Moreover, the heating and illumination stability of modified devices by virtue of defect suppression located at electron transfer layer (ETL)/perovskite interface has been effectively improved, retaining over 85% of its initial PCE after 7 h heating at 100 °C in ambient condition and 85% of its initial PCE under 7 h continuous light illumination without any encapsulation. Therefore, it is believed that this Yb-doping strategy for SnO2 ETL can provide a novel way of promoting the efficiency and stability of devices prepared in the air.