Simultaneous low-order phase suppression and defect passivation for efficient and stable blue light emitting diodes

Abstract

Quasi-2D perovskite is considered as a promising candidate for blue perovskite light emitting diode (PeLEDs). However, the wide distribution of low-order phases, inefficient energy transfer, and defects/traps increase the non-radiative recombination, further aggravating PeLED external quantum efficiency (EQE). We demonstrate a unique quasi-2D perovskite with low-order phase suppression and defect passivation by incorporating a 2D perovskite and an excess ammonium salt into the quasi-2D perovskite. By optimizing the new quasi-2D perovskites, we achieve blue PeLEDs with brightness 1765 cd m-2, EQE 7.51%, low turn-on voltage 3.07 V, and long operation lifetime 3961 sec without any shift in electroluminescent spectra.