Bottom-up passivation effects by using 3D/2D mix structure for high performance p-i-n perovskite solar cells

Perovskite solar cells (PSCs) have shown a great potential in the field of alternative energy due to their superior performance and processing compatibility. However, prior to commercialization, a major drawback of poor stability needs to be addressed imperatively. Recently, mixing 3D and 2D perovskite as active layer is a promising strategy for blocking water and oxygen to increase stability, as well as mitigating the effect of insulated spacer in bulk to strengthen charge migration. Here, we report a novel method to fabricate high-performance inverted PSCs by involving Phenethylammonium bromide (PEABr) as passivator. During the fabrication, PEABr will diffuse into 3D perovskite and form a mixed 3D/2D structure at the lower interface. This ingenious structure will restrain the charge recombination and reduce the trap state density at the transport layer/perovskite interface and bulk of 3D perovskite. Due to the bottom-up passivation effects, mixed 3D/2D PSCs achieve an improved PCE from 17.59% to 19.46%, in combination with enhanced long-term air stability. This 3D/2D mix structure demonstrates a great potential for developing high-performance and high stability PSCs.