A Strategy for Architecture Design of Crystalline Perovskite Light-Emitting Diodes with High Performance.

All present designs of perovskite light-emitting diodes (PeLEDs) stem from polymer light-emitting diodes (PLEDs) or perovskite solar cells. The optimal structure of PeLEDs can be predicted to differ from PLEDs due to the different fluorescence dynamics and crystallization between perovskite and polymer. Herein, a new design strategy and conception is introduced, "insulator-perovskite-insulator" (IPI) architecture tailored to PeLEDs. As examples of FAPbBr3 and MAPbBr3 , it is experimentally shown that the IPI structure effectively induces charge carriers into perovskite crystals, blocks leakage currents via pinholes in the perovskite film, and avoids exciton quenching simultaneously. Consequently, as for FAPbBr3 , a 30-fold enhancement in the current efficiency of IPI-structured PeLEDs compared to a control device with poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) as hole-injection layer is achieved-from 0.64 to 20.3 cd A-1 -while the external quantum efficiency is increased from 0.174% to 5.53%. As the example of CsPbBr3 , compared with the control device, both current efficiency and lifetime of IPI-structured PeLEDs are improved from 1.42 and 4 h to 9.86 cd A-1 and 96 h. This IPI architecture represents a novel strategy for the design of light-emitting didoes based on various perovskites with high efficiencies and stabilities.