Metal Halide Perovskites: Processing, Interfaces, and Light Emitting Devices

Abstract

Abstract:We study the use of metal halide perovskites for light emitting diode (LED) applications. Through understanding of interface chemistry and improvements in film formation, we demonstrate green and red perovskite LEDs with external quantum efficiencies of approximately 10%. [1,2]. However, solution processed perovskite films and devices commonly suffer from poor thin film quality, reproducibility, and stability.Our recent work that will be the subject of this tutorial presentation has determined that the fabrication of MAPbI 3 thin films displays all of the hallmarks of sol-gel processing [3]. By performing a solvent exchange at different times, the stages of the sol-gel process are elucidated and the sensitivity to processing conditions are examined. We show that the reaction and aging kinetics are extremely rapid, complete within 6 s during spin coating. We realize films with roughness on the order of 1 nanometer that consist of nanoscale crystallites, formed by incorporating a bulky organoammonium halide in addition to the stoichiometric 3D perovskite precursors [3,4,5]. These bulky ligands passivate the 3D crystal, lead to considerably enhanced luminescence quantum yields, and increase stability. LEDs produced in this way are capable of exceeding 10% external quantum efficiency and exhibit significantly improved stability.Finally, we have determined that these metal halide perovskites are considerably redox active [6], and are looking to understand how redox chemistry dictates material and device physics and degradation. References