Simulations of Trions and Biexcitons in Layered Hybrid Organic-Inorganic Lead Halide Perovskites

TL;DR

This study models and analyzes the properties of trions and biexcitons in layered hybrid organic-inorganic lead halide perovskites, revealing their binding energies and structures through advanced computational methods.

Contribution

It introduces a parameterized Hamiltonian and computational approach to study complex excitonic states in layered HOIPs, providing new insights into their binding energies and spatial configurations.

Findings

Trion binding energy in the thinnest layered HOIP is 35 meV.

Biexciton binding energy in the thinnest layered HOIP is 44 meV.

Exfoliated single layers have trions and biexcitons with 48 meV binding energies.

Abstract

Behaving like atomically-precise two-dimensional quantum wells with non-negligible dielectric contrast, the layered HOIPs have strong electronic interactions leading to tightly bound excitons with binding energies on the order of 500 meV. These strong interactions suggest the possibility of larger excitonic complexes like trions and biexcitons, which are hard to study numerically due to the complexity of the layered HOIPs. Here, we propose and parameterize a model Hamiltonian for excitonic complexes in layered HOIPs and we study the correlated eigenfunctions of trions and biexcitons using a combination of diffusion Monte Carlo and very large variational calculations with explicitly correlated Gaussian basis functions. Binding energies and spatial structures of these complexes are presented as a function of the layer thickness. The trion and biexciton of the thinnest layered HOIP have binding energies of 35 meV and 44 meV, respectively, whereas a single exfoliated layer is predicted to have trions and biexcitons with equal binding enegies of 48 meV. We compare our findings to available experimental data and to that of other quasi-two-dimensional materials.