Surface geometry determined temperature-dependent band structure evolutions in organic halide perovskite single crystals

TL;DR

This study reveals how surface geometry influences temperature-dependent band structure changes in organic halide perovskite single crystals, highlighting surface effects on electronic properties crucial for device interfaces.

Contribution

It demonstrates that surface geometries cause distinct band structure evolutions in perovskite crystals, emphasizing the importance of surface considerations in device development.

Findings

Surface geometry affects band structure evolution.

Rashba splitting observed in CH3NH3PbBr3.

Surface layers determine electronic structure changes.

Abstract

In this study, different electronic structure evolutions of perovskite single crystals are found via angle-resolved photoelectron spectroscopy (ARPES): (i) unchanged top valence band (VB) dispersions under different temperatures can be found in the CH3NH3PbI3, (ii) phase transitions induced the evolution of top VB dispersions, and even a top VB splitting with Rashba effects can be observed in the CH3NH3PbBr3. Combined with low-energy electron diffraction (LEED), metastable atom electron spectroscopy (MAES), and DFT calculation, we confirm different band structure evolutions observed in these two perovskite single crystals are originated from the cleaved top surface layers, where the different surface geometries with CH3NH3+-I in CH3NH3PbI3 and Pb-Br in CH3NH3PbBr3 are responsible for finding band dispersion change and appearing of the Rashba-type splitting. Such findings suggest that the top surface layer in organic halide perovskites should be carefully considered to create functional interfaces for developing perovskite devices.