Two-Dimensional Dion-Jacobson Structure Perovskites for Efficient Sky-Blue Light-Emitting Diodes

Two-dimensional Ruddlesden-Popper (RP) and Dion-Jacobson (DJ) phase perovskites are promising alternatives to fabricate blue perovskite light-emitting diodes (PeLEDs) due to their strong quantum/dielectric confinement. While the RP phase perovskites have been widely used as emitter layers in blue PeLEDs, the DJ phase perovskites, possessing better structural stability and charge transfer property, have received little attention. Here, we report the use of DJ phase perovskites for fabricating efficient sky-blue PeLEDs. Organic diamine propane-1,3-diammonium cations were first incorporated into CsPbBr3 to prepare DJ phase perovskites. RbBr was further incorporated as a passivation agent to eliminate traps. It is found that diamine cations and RbBr are interdependent in terms of increasing the utilization of charges. Radiative recombination was enhanced, effectively benefiting from the synergetic confinement and passivation effects. The photoluminescence quantum yield approached 70%. Finally, the fabricated PeLEDs achieved an external quantum efficiency of 8.5% with an emission peak at 490 nm.