Chemical bath deposition of mesoporous SnO2 to improve interface adhesion and device operational stability

The material and microstructure of the carrier-selective layers in the perovskite solar cells are important to determining their efficiency and stability. Planar SnO2 is the most commonly used inorganic electron transport layer, but there are few reports of its mesoporous structure because of the degradation of hole-blocking property after high temperature sintering. Here, the chemical bath deposition method was optimized to realize low-temperature in-situ deposition of mesoporous SnO2 layer on FTO substrates. On one hand, the increased interface contact area improves electron injection from the perovskite layer to the SnO2, yielding an impressive increase of the power conversion efficiency from 22.09% to 24.11%. And on the other hand, thanks to the increased mechanical strength of the interface, the device with mesoporous SnO2 retains 90% of its initial power conversion efficiency after 1000 h operation under continuous one-sun illumination.