Improved Environmental Stability and Solar Cell Efficiency of (MA,FA)PbI₃ Perovskite Using a Wide-Band-Gap 1D Thiazolium Lead Iodide Capping Layer Strategy

There is strong interest in improving the environmental stability of hybrid perovskite solar cells while maintaining high efficiency. Here, we solve this problem by using epilayers of a wide-band-gap 1D lead iodide perovskitoid structure, based on a short organic cation, namely, thiazole ammonium (TA) in the form of lead iodide (TAPbI₃). The 1D capping layer serves to passivate three-dimensional (3D) perovskite films, which promotes charge transport, improves carrier lifetime, and prevents iodide ion migration of the 3D (MA,FA)PbI₃ film (MA = methylammonium, FA = formamidinium). Furthermore, the corresponding device achieved considerable efficiency and better environmental stability than the -based analogue, delivering a champion PCE value of 18.97% while retaining 92% of this efficiency under ambient conditions in air for 2 months. These findings suggest that utilization of a 1D perovskitoid is an effective strategy to improve the environmental stability of 3D-based perovskite solar cell devices maintaining at the same time their high efficiency.