Vapor-Phase Growth of CsPbBr3 Microstructures for Highly Efficient Pure Green Light Emission

All-inorganic lead halide perovskites have been extensively studied in the past several years due to their superior stability against moisture, oxygen, light, and heat compared with their organic-inorganic counterparts. CsPbBr3 with suitable band gap and ultrahigh photoluminescence quantum yield is a promising candidate for pure green emitter in the backlighting display to fill the so-called green gap. Here, vapor-phase growth of CsPbBr3 microspheres is reported for highly efficient pure green light emission. The as-synthesized microspheres exhibit a stronger photoluminescence (PL) intensity with a photoluminescence quantum yield of 75% resulting from the lower energy of longitudinal optical phonons revealed by temperature dependent PL studies. Importantly, with the diameter increasing from 2 to 50 mu m the PL peak positions of the microspheres can be readily tuned from 527 to 539 nm, well filling the so-called green gap. The red-shift with increasing diameter can be ascribed to the reabsorption process during the photon propagation inside the microspheres. The studies provide a route to improve the photoluminescence quantum yield in all-inorganic lead halide perovskites, but also suggest an alternative approach to achieve the pure green emission for the backlighting display.