Operationally Stable Perovskite Light Emitting Diodes with High Radiance

Although perovskite light emitting diodes (PeLEDs) have shown fast advances in external quantum efficiency (EQE), their operational stability is still low compared to other LED devices. Here, stable PeLEDs are demonstrated with high radiance primarily by using 6,6′-phenyl-C61-butyric acid methyl ester (PCBM) and magnesium-doped Zinc oxide (ZnMgO) injection layers to reduce the driving voltage. Through different characterizations, it is revealed that the use of PCBM/ZnMgO electron injection layer can effectively mitigate Joule heating, block the migration of Al electrode towards perovskite layer as well as avoid the breakdown of main perovskite crystal structure under prolonged operation. Combining the PCBM/ZnMgO electron injection layer with a formamidinium-based perovskite light emitter, the optimal device shows an EQE of 11.4% at 330 mA cm−2 and a radiance of 399 W Sr−1 m−2 at 3.1 V. The device remains above 50% of the maximum performance after operating for 525 and 118 h at constant current densities of 50 and 100 mA cm−2, respectively. Thus, this work presents a substantial improvement in the stability of PeLEDs and the methods to consolidate this progress even further. © 2021 Wiley-VCH GmbH