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 FAPbBr 3 ‐based green PeLEDs is hindered by detrimental interfacial reactions at ZnO/perovskite interfaces. Here, an efficient silicon oxide (SiO 2 ) modification strategy is presented for ZnO ETL to regulate interfacial reactions between ZnO and FAPbBr 3 . Introducing tetraethyl orthosilicate (TEOS) during ZnO sol‐gel fabrication, a conformal SiO 2 coating forms on the ZnO surface after calcination. This modification effectively suppressed interfacial deprotonation between ZnO and FAPbBr 3 , thereby mitigating FA + depletion and enabling the formation of a highly crystalline and uniform FAPbBr 3 film. The resultant ZnO‐based green PeLEDs achieved a maximum luminance exceeding 3.0 × 10 5 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‐x Cl 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.