Efficient Sky‐Blue Light‐Emitting Diodes Based on Oriented Perovskite Nanoplates

Abstract Excessive organic ligands damage the crystallinity of blue quasi‐2D perovskite, resulting in a small‐grain film with a high grain boundary ratio. Herein, oriented blue perovskite nanoplates are fabricated by using antisolvent additive engineering to tackle this issue. The introduction of triphenylphosphine oxide additive in antisolvents significantly increases the perovskite grain sizes, laying the foundation for in situ formation of perovskite nanoplates. The miscibility between ethyl acetate antisolvent and dimethyl sulfoxide host solvent affects formation of the oriented perovskite nanoplates. The perovskite film containing oriented nanoplates with enhanced crystallinity exhibits elevated photoluminescence quantum yield as compared to the control samples. Based on the oriented perovskite nanoplates, blue perovskite light‐emitting diodes (PeLEDs) with an emission peak at 488 nm and a maximum external quantum efficiency of 9.5% are successfully fabricated. Moreover, the blue PeLEDs deliver a high brightness of 4256 cd m^–2 with stable electroluminescent spectra.