High-n Phase Suppression for Efficient and Stable Blue Perovskite Light-Emitting Diodes

Quasi-2D perovskites light-emitting diodes (PeLEDs) have achieved significant progress due to their superior optical and electronic properties. However, the blue PeLEDs still exist inefficient energy transfer and electroluminescence performance caused by mixed multidimensional phase distribution. In this work, transition metal salt (zinc bromide, ZnBr2) is introduced to modulate phase distributions by suppressing the nucleation of high n phase perovskites, which effectively shortens the energy transfer path for blue emission. Moreover, ZnBr2 also facilitates energy level matching and reduces non-radiative recombination, thus improving electroluminescence (EL) efficiency. Benefiting from these combined improvements, an efficient blue PeLEDs is obtained with a maximum external quantum efficiency (EQE) of 16.2% peaking located at 486 nm. This work provides a promising approach to tune phase distribution of quasi-2D perovskites and achieving highly efficient blue PeLEDs. An efficient quasi-2D blue PeLEDs at 486 nm are realized by employing transition metal salt (ZnBr2). The high Br-to-Pb ratio exhibits superior phase distribution control, which suppresses the growth of the high-n phase and shortens the carrier transfer path between different n phases for highly blue PeLEDs. As a result, the ZnBr2-assisted devices achieve a maximum external quantum efficiency (EQE) of 16.2%. image