Cation Engineering for Resonant Energy Level Alignment in Two-Dimensional Lead Halide Perovskites

Low-dimensional metal halide perovskites are being intensively investigated because of their higher stability and chemical versatility in comparison to their 3D counterparts. Unfortunately, this comes at the expense of the electronic and charge transport properties, limited by the reduced perovskite dimensionality. Cation engineering can be envisaged as a solution to tune and possibly further improve the material's optoelectronic properties. In this work, we screen and design new electronically active A-site cations that can promote charge transport across the inorganic layers. We show that hybridization of the valence band electronic states of the perovskite inorganic sublattice and the highest occupied molecular orbitals of the A-site organic cations can be tuned to exhibit a variety of optoelectronic properties. A significant interplay of A-cation size, electronic structure, and steric constraints is revealed, suggesting intriguing means of further tuning the 2D perovskite electronic structure toward achieving stable and efficient solar cell devices.

Automated summary

This study investigates the use of cation engineering to improve the optoelectronic properties of 2D perovskites, showing that electronically active A-site cations can enhance charge transport. Tuning the hybridization of electronic states can lead to a variety of optoelectronic properties, with implications for stable and efficient solar cell devices.