High Radiance of Perovskite Light‐Emitting Diodes Enabled by Perovskite Heterojunctions

AbstractMetal‐halide perovskites (MHPs) have made incredible achievements in the past few years, especially in the area of perovskite light‐emitting diodes (PeLEDs). Nevertheless, hole transport layers (HTLs) used in most highly efficient PeLEDs usually have low hole mobilities in the range of 10−4–10−6 cm2 V−1 s−1, much lower than that of MHPs, resulting in severe roll‐off and low radiance of the devices. Here, methylammonium lead iodide (MAPbI3) is successfully deposited on top of methylammonium lead chloride (MAPbCl3) using orthogonal solvent to form heterojunction PeLEDs (HJ‐PeLEDs). Due to the high hole mobility of MAPbCl3 ≈42 cm2 V−1 s−1, the HJ‐PeLEDs exhibit a peak external quantum efficiency of 10.7% and a high radiance of 157 W sr−1 m−2 at a low applied voltage of 3.9 V. Furthermore, the large‐area (28 cm2) HJ‐PeLEDs made by blade coating shows a uniform and high radiance of ≈180 W sr−1 m−2. This work provides a novel strategy to fabricate bright and large‐area PeLEDs to meet the requirements of commercial applications.