Propylamine hydrobromide passivated tin-based perovskite for efficient solar cells

It is significant for the commercial viability of perovskite solar cells to develop tin-based devices with low toxicity. However, tin halide is a stronger Lewis acid, so that its crystallization rate is very fast, which leads to the formation of many defects that influence the device performance of tin-based perovskite solar cells. In this work, Propylamine hydrobromide (PABr) is introduced into the perovskite precursor solution as an additive to passivate defects, fabricating more uniform and dense perovskite films. Because they are too large to enter the perovskite lattices, propylamine cations just exist in the grain boundary to passivate surface defects and to promotes crystal growth in a favored orientation. The average short circuit current density is enhanced from 19.45 to 25.47 mA per square centimeter due to PABr additive because carrier recombination induced by defects is substantially decreased. In addition, the long-term illumination stability of the device is enhanced after optimization, and the hysteresis effect is negligible. Attributing to the addition of PABr, a power conversion efficiency of 9.35 percent is achieved.