First-principles investigation on molecular adsorption on 2D perovskite toward optoelectronic application

Abstract

Halide perovskite materials have received attention for optoelectronic applications, and it is promising to further engineer the perovskite systems via surface molecular adsorption to improve optoelectronic properties. In this study, we comprehensively investigate atomic structures and properties of surface molecule-modified low-dimensional halide perovskite systems represented by Cs2PbBr4 via first-principles calculations. The calculation pinpoints the effectiveness of molecular adsorption to fine tune the structural and electronic properties of low-dimensional halide perovskite material, which can be stabilized via interfacial secondary bonds such as anion···π, halogen bond and hydrogen bond interactions. Noteworthily, the anion···π interaction is almost ubiquitous in the aromatic molecule/perovskite systems in the present study assuming the adsorption mode is horizontal, signifying the versatility of anion···π interaction to functionalize low-dimensional halide perovskite surfaces. In addition, the amine-containing molecules tend to initiate molecule → perovskite interfacial charge transfer direction upon light excitation while most other organic molecules favors halogen → lead electron transfer process inside the perovskite substrate. Importantly, the polaron calculations suggest the possibility of forming large polarons to protect charge transport via effective electron- and hole-phonon coupling upon molecular adsorption. This study highlights the effectiveness of organic molecule adsorption to fine tune optoelectronic properties of low-dimensional perovskite systems via the formation of interfacial secondary bonds.