Interactions between gas molecules and two-dimensional Ruddlesden–Popper halide perovskite

The interactions between the atmospheric gas molecules and the halide perovskite materials are critical for understanding the optoelectronic performance and stability of the perovskite solar cells. In this article, we employ first-principles calculations to systematically investigate the interactions between the atmospheric gas molecules and the two-dimensional Ruddlesden–Popper halide perovskite based on (BA)2(MA)1Pb2I7. The gas molecules influence the electronic and optical properties of the two-dimensional perovskite systems, and the interfacial structures of the seven gas/perovskite systems are stabilized via the formation of the hydrogen bonds. The small amount of electron transfer from the gas molecule to the perovskite substrate is ubiquitous to further stabilize the overall structures. The SO2 introduces deep defects to the perovskite material, which can significantly damage the electronic properties. With light excitation, the gas molecule adsorption is expected to offer disparate interfacial charge transfer directions, with SO2 and CO causing the perovskite→molecule charge transfer upon light excitation and NH3, H2S, and H2O causing the interfacial charge transfer in the reverse direction. This study reveals the atomistic view of the interactions between the atmospheric gas and the Ruddlesden–Popper halide perovskite materials and highlights the importance of considering the atmospheric gas for the perovskite design process.