An Easily Developed Difunctional Molecule Enabling Highly Efficient and Stable Light‐Emitting Diodes

Abstract The surface treatment for solution‐processed perovskite films using molecular passivation agents has been reported to be critical for improving the performance of perovskite light‐emitting diodes (PeLEDs). Generally, most studies emphasized the binding effect between passivation molecules and perovskite surface, while halide perovskites are dominated by multiple defects and need more comprehensive passivation, which is often neglected. Here, a molecule of 5‐ammonium valeric acid trifluoroacetate (5‐AVATFA) with multi‐functional groups is rationally developed to modify the interface of advanced PeLEDs. Combining experimental and density functional theory analysis, the synergism effects of reduced surface defects and increased steric hindrance of 5‐AVATFA, which can greatly suppress the ion migration of PeLEDs, are demonstarated. Because of the passivation effect of multi‐functional 5‐AVATFA, an optimal device with an external quantum efficiency of 22.32%, a radiance of 558.46 W sr −1 m −2 , and an extended half‐lifetime of 103.3 h is obtained.