The role of lattice mismatch on the emergence of surface states in 2D hybrid perovskite quantum wells

TL;DR

This study investigates how lattice mismatch influences surface state formation in 2D hybrid perovskite quantum wells, revealing that interface strain relaxation triggers edge states that affect optoelectronic properties.

Contribution

It introduces a generic elastic and electronic structure model showing how lattice mismatch induces surface states in layered halide perovskites, impacting device design.

Findings

Surface states emerge when interface strain relaxes above a critical layer thickness.

Lattice mismatch leads to surface reorganization and lower energy edge states.

Surface states significantly influence the optoelectronic properties of 2D perovskites.

Abstract

Surface states are ubiquitous to semiconductors and significantly impact the physical properties and consequently the performance of optoelectronic devices. Moreover, surface effects are strongly amplified in lower dimensional systems such as quantum wells and nanostructures. Layered halide perovskites (LHPs) are 2D solution-processed natural quantum wells, where optoelectronic properties can be tuned by varying the perovskite layer thickness. They are efficient semiconductors with technologically relevant stability. Here, a generic elastic model and electronic structure modelling are applied to LHPs heterostructures with various layer thickness. We show that the relaxation of the interface strain is triggered by perovskite layers above a critical thickness. This leads to the release of the mechanical energy arising from the lattice mismatch, which nucleates the surface reorganization and consequently the formation of lower energy edge states. These states, which are absent in 3D perovskites, dominate the optoelectronic properties of LHPs and are anticipated to play a crucial role in the design of LHPs for optoelectronics devices.