Perovskite Quantum Dots with Atomic Crystal Shells for Light-Emitting Diodes with Low Efficiency Roll-Of

Light-emitting diodes (LEDs) employing all-inorganic CsPbX₃ (X = Cl, Br, I) perovskite quantum dots offer a huge potential in terms of high electroluminescence efficiency, color purity, and wide color gamut. However, the unbalanced charge injection and low ion-migration activation energy in perovskite active layers may cause device efficiency to decline with the increase of brightness and current density, which is a so-called efficiency roll-off effect. In this Perspective, we offer design principles toward construction of ionic crystal {perovskite}/atomic crystal {semiconductor alloy materials} core/shell quantum dots, which can serve as emitters for perovskite-based LEDs with a low efficiency roll-off. Considering the lattice constant matching and the proper energy level arrangement for the core and shell, we suggest that the CsPbI₃/Mg_xZn_1-xTe core/thick shell quantum dots may simultaneously offer enhanced emission, balanced charge injection, and suppressed ion migration and thus be a suitable emitter for LEDs with simultaneous high brightness and efficiency.