Hybrid organic-inorganic halide perovskite materials such as methylammonium lead iodide are gaining interest in the thin film optoelectronics community due to their promising optoelectronic properties. We have established a processing paradigm to realize films with roughness on the order of 1 nanometer that consists of nanoscale crystallites, formed by incorporating a bulky organoammonium halide in addition to the stoichiometric 3D perovskite precursors. These bulky ligands passivate the 3D crystal, enhance luminescence quantum yields, allow for stable mixed halide stoichiometries, increase stability, and improve flexibility. We demonstrate highly efficient and flexible perovskite LEDs with external quantum efficiency (EQE) up to ~13%, values that are higher than the ITO-based controls (~10%). Also, we will show how these smooth films can be employed in optically pumped laser structures.
In another aspect, we have determined that metal halide perovskites are considerably redox active, and are looking to understand how redox chemistry dictates material and device physics and degradation.