Nonmonotonic Photostability of BA2MAn-1PbnI3n+1 Homologous Layered Perovskites

Layered lead halide perovskites (2D LHPs) are attracting considerable attention as a promising material for a new generation of solar cell devices. LHPs have been presented as a more stable alternative to the more widespread 3D bulk perovskite materials; however, a critical analysis of their photostability is still lacking. In this work, we perform a comparative study between BA(2)MA(n-1)Pb(n)I(3n+1) (BA-butylammonium and MA-methylammonium 2D LHPs with different dimensionalities (n = 1-3) and MAPbI(3) 3D perovskites. We compare different stability testing protocols including photometrical determination of iodine-containing products in nonpolar solvents, X-ray diffraction, and photoluminescence (PL) spectroscopy. The resulting trends of the photostability in an inert atmosphere based on PL spectroscopy measurements demonstrate a nonmonotonic dependence of the degradation rate on the perovskite layer thickness n with a stability island at n >= 3, which is caused by a combination of antibate factors of electronic structures and chemical compositions in the family of 2D perovskites. We also identify a critical oxygen concentration in the surrounding environment that affects the mechanism and strongly enhances the rate of layered perovskite photodegradation.

Automated summary

Layered lead halide perovskites (2D LHPs) are being studied as a promising material for solar cell devices. The research shows that thicker layers of 2D LHPs (n>=3) exhibit better photostability, with the surrounding oxygen concentration playing a critical role in the photodegradation process.