Room Temperature Epitaxy of CH3NH3PbI3 Halide Perovskite by Pulsed Laser Deposition

Abstract

Epitaxial growth on lattice-(mis)matched substrates has advanced our understanding of semiconductors and enabled high-end technologies like III-V-based LEDs. However, for the promising metal halide perovskite (MHP) semiconductors, there is a significant knowledge gap in thin film heteroepitaxial growth, hindering progress towards new high-end applications with improved optoelectronic performance. Here we demonstrate the epitaxial growth of CH3NH3PbI3 ultrathin films on lattice matched KCl substrates. This is enabled by pulsed laser deposition (PLD) at room temperature. Epitaxial stabilization of the cubic CH3NH3PbI3 polymorph is confirmed via photoluminescence, indicating a band gap of 1.66 eV stable for over 200 days and Urbach energies of 12.3 meV for 13 nm thick films. The strains’ impact on cubic phase stabilization is corroborated by first-principle DFT calculations, which also predict substantial bandgap tunability under strain. This work demonstrates the potential of PLD for thickness-controlled vapor-phase heteroepitaxial growth of MHPs, inspiring studies on heterostructures and strain modulation to unlock novel functionalities.