High‐Efficiency Solution‐Processed Inorganic Metal Halide Perovskite Light‐Emitting Diodes

This paper reports highly bright and efficient CsPbBr 3 perovskite light‐emitting diodes (PeLEDs) fabricated by simple one‐step spin‐coating of uniform CsPbBr 3 polycrystalline layers on a self‐organized buffer hole injection layer and stoichiometry‐controlled CsPbBr 3 precursor solutions with an optimized concentration. The PeLEDs have maximum current efficiency of 5.39 cd A −1 and maximum luminance of 13752 cd m −2 . This paper also investigates the origin of current hysteresis, which can be ascribed to migration of Br − anions. Temperature dependence of the electroluminescence (EL) spectrum is measured and the origins of decreased spectrum area, spectral blue‐shift, and linewidth broadening are analyzed systematically with the activation energies, and are related with Br − anion migration, thermal dissociation of excitons, thermal expansion, and electron–phonon interaction. This work provides simple ways to improve the efficiency and brightness of all‐inorganic polycrystalline PeLEDs and improves understanding of temperature‐dependent ion migration and EL properties in inorganic PeLEDs.