Effect of Stacking 2D Lead Chloride Perovskites into Vertical Heterostructures on Photoluminescence Intensity

Two-dimensional organic-inorganic hybrid lead halide perovskites are of interest for photovoltaic and light emitting devices due to their relative stability when compared to bulk lead halide perovskites and favorable properties that can be tuned. Tuning of the material can be performed by adjusting halide composition or by taking advantage of confinement effects. Here we use the density functional theory and excited state dynamics treated by the reduced density matrix method to examine the effects of the variation of the perovskite layer thickness on the ground-state and excited-state photo-physical properties of the materials; further we explore the effects of a vertical heterostructure of perovskite layers. Nonadiabatic couplings were computed based on the on-the-fly approach along a molecular dynamic trajectory at ambient temperatures. The density matrix-based equation of motion for electronic degrees of freedom is used to calculate the dynamics of electronic degrees of freedom. We found that the vertical stacking of two-dimensional perovskites into heterostructures shows an increase in photoluminescence intensity by two orders of magnitude when compared to the individual two-dimensional perovskites.