Dual‐Sided Interface Optimization Enables High‐Brightness All‐Solution‐Processed ZnMgO‐Based Green Perovskite QLEDs

The degradation of the underlying perovskite quantum dot (PQD) layers by the ZnMgO ink hinders the performance of all‐solution‐processed perovskite quantum dot light‐emitting diodes (P‐QLEDs). Herein, a novel dual‐sided interface optimization is proposed for the fabrication of P‐QLEDs: (i) cross‐locking PQD surface ions with a robust zwitterionic ligand to boost their chemical and solvent tolerance; (ii) improving ink orthogonality via optimizing the solvent of ZnMgO to acetonitrile and eliminating residual hydroxyl groups from the ZnMgO surface. As a result, the ZnMgO is deposited on the PQD films without causing serious degradation, leading to improved carrier injection and radiative recombination. The optimized P‐QLEDs achieve a maximum luminance of 134 920 cd m −2 and a peak external quantum efficiency (EQE) of 8.3%, ranking among the state‐of‐the‐art all‐solution‐processed green‐emitting devices.