| Abstract: | Metal halide perovskite light-emitting diodes (PeLEDs)show great potential in ultra-high-definition displays,due to their narrowband emission,wide color gamut (～140％),and cost-effective solution processability1]M.Thanks to scientists' tremendous efforts,the external quantum efficiencies (EQEs)for the state-of-the-art PeLEDs emitting near-infrared and green light have reached 21.6％2] and 23.4％3],respectively.However,blue PeLEDs,as one of the essential technologies for perovskite-based high-resolution monitors and white light-ing,are still inferior to their red and green counterparts.Blue emission is usually achieved by using dimensional engineer-ing (quantum confinement) or composition engineering(mixed halides,e.g.,mixed Br/Cl) strategies.For example,quasi-two-dimensional (2D) perovskites,nanocrystals (e.g.,quantum dots,QDs) or nanoplates,give blue emission due to quantum confinement effects.However,achieving pure-blue(465-475 nm) and deep-blue (420-465 nm) light from quasi-2D perovskites is challenging4],while ultra-small QDs and nanoplates suffer from high surface trap density and poor sta-bility5].For PeLEDs based on mixed Br/Cl perovskites,the emis-sion peak can be tuned easily,but these perovskites face the disadvantages of phase separation and deep energy-level Cl vacancies4]. |
