Lead halide perovskites are being studied due to their favorable properties for photovoltaic and light emitting devices. Long-term stability of the perovskite solar cell, which exhibit photo, moisture, and thermal stability weaknesses, is the main challenge currently limiting their application. Two-dimensional inorganic-organic hybrid perovskites offer increased stability and higher tunability of physical properties. Adjusting the thickness of the perovskite layer in the two-dimensional hybrid perovskite allows for tuning the band gap. By combining different perovskites of different thicknesses into a single structure termed heterostructure, we hope that we can use the varied band gap to control the separation of the electron and hole. Here we are examining the effect that a horizontal heterostructure of perovskite thicknesses has on the photophysical and charge transfer properties using density functional theory and excited state dynamics. The on-the-fly approach was used to calculate nonadiabatic couplings along a molecular dynamics trajectory at ambient temperatures. Density matrix-based equation of motion for electronic degrees of freedom is used to calculate the dynamics of electronic degrees of freedom. The horizontal heterostructure perovskite, with its two different thickness perovskite layers, shows a promising effect towards charge separation due to the different sized band gaps for the different sized perovskite layers.

Charge separation in two-dimensional hybrid lead halide perovskites horizontal heterostructures

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