Dually-passivated planar SnO2 based perovskite solar cells with ˃2,700h ambient stability: Facile fabrication, high performance and mechanism

In SnO 2 -based planar perovskite solar cells (SP–PSCs), stability issue derived by defects at grain boundaries (GBs) and surface in perovskite films has been one of the main reasons that limit its commercialization. Therefore, co-passivation of both defects is pivotal to maximize passivation effects for improving power conversion efficiency (PCE) and stability, which is rarely reported in SP-PSCs. Herein, two simple passivating agents including Pb(SCN) 2 and choline chloride (ChCl) were selected to dually passivate GBs and surface defects in the perovskite films (ambient atmosphere), respectively. The influences of co-passivation on PCE and ambient stability of devices were intensively studied, and the related mechanisms were also elucidated in detail. The dually-passivated device obtained a champion PCE of 19.98%, and maintained about 94% of the initial efficiency after being stored for ˃2700h aging in the humid air. The reduction of GBs and surface defects not only weakens the non-radiative recombination of carriers, but also inhibits the penetration of moisture and oxygen, which ultimately greatly enhances the PCE and stability of the device. This paper provides support for the dual passivation of GBs and surface defects to ameliorate ambient stability of the SP-PSCs, and also enriches the selectivity of passivation agents on dual passivation.