Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals

TLDR

Organolead trihalide perovskites (MAPbX3) have their fundamental properties and performance limits obscured by disorder in polycrystalline films. The study aims to develop an antisolvent vapor‑assisted crystallization method to produce large, crack‑free MAPbX3 single crystals. The method yields crystals over 100 mm³, enabling detailed optical and charge‑transport characterization. The crystals exhibit trap‑state densities of 10^9–10^10 cm⁻³ and carrier diffusion lengths >10 µm, comparable to high‑quality silicon, as confirmed by density‑functional theory.

Abstract

The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3 (MA = CH3NH3(+); X = Br(-) or I(-)) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics. We observed exceptionally low trap-state densities on the order of 10(9) to 10(10) per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.