Ultra‐Bright Green Perovskite Light‐Emitting Diodes Enabled by Silicon Oxide‐Modified Zinc Oxide Electron Transport Layer

Abstract Perovskite light‐emitting diodes (PeLEDs) exhibit exceptional potential for next‐generation high definition displays. As a promising electron transport layer (ETL), inorganic zinc oxide (ZnO) can endow PeLEDs with high brightness due to its high electron mobility. However, their application in FAPbBr₃‐based green PeLEDs is hindered by detrimental interfacial reactions at ZnO/perovskite interfaces. Here, an efficient silicon oxide (SiO₂) modification strategy is presented for ZnO ETL to regulate interfacial reactions between ZnO and FAPbBr₃. Introducing tetraethyl orthosilicate (TEOS) during ZnO sol‐gel fabrication, a conformal SiO₂ coating forms on the ZnO surface after calcination. This modification effectively suppressed interfacial deprotonation between ZnO and FAPbBr₃, thereby mitigating FA⁺ depletion and enabling the formation of a highly crystalline and uniform FAPbBr₃ film. The resultant ZnO‐based green PeLEDs achieved a maximum luminance exceeding 3.0 × 10⁵ cd m⁻², with peak external quantum efficiency (EQE) improved from 5.0% to 10.8% compared to unmodified devices. Furthermore, this modification is applied in blue PeLEDs using FAPbBr_3‐xCl_x emitter layer, delivering a peak luminance of 1003 cd m⁻². This work provides a feasible interfacial engineering strategy for ZnO ETL to achieve high‐brightness PeLEDs.