2, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Recently, there is a renaissance of halide perovskites as a promising class of light-emitting materials because of their unusual optoelectronic properties. Particularly, the inorganic halide perovskites attracted more and more attention, owing to their enhanced stability toward moisture, oxygen, and heat, compared to the organic-inorganic hybrid perovskites (e.g. methylammonium lead iodide). Low-dimensional nanostructured perovskites provide controllable morphology, tunable emission, and improved quantum efficiency. This talk will focus on the new strategies towards inorganic halide perovskite nanostructures and heterojunctions, as well as their emerging applications in nanoscopic lasers and high-definition displays.
We develop the advanced synthetic methodology of CsPbX3 nanostructures with desired sizes, compositions, and optical properties, including colloidal, solution-phase and vapor-phase approaches. Colloidal nanowires exhibit highly efficient photoluminescence, with well-controlled morphology and tunable diameter range from 10 to 2 nm. Mesoscopic single-crystal nanostructures from solution-phase growth were demonstrated as the efficient optical medium for high-performance and robust nanoscopic lasers. Vapor-phase methods generally have better crystalline quality and lower defect density for improved optoelectronic properties. Due to the relatively weak bonding in halide perovskites, anion exchange was demonstrated in these materials with high PLQY throughout the exchange reaction. Moreover, we demonstrate spatially resolved multi-color CsPbX3 nanowire heterojunctions through localized anion exchange. These perovskite heterojunctions show tunable photoluminescence over the entire visible spectrum with high resolution down to 500 nm, which represent key building blocks for high-resolution displays.