Efficient Quantum Dot Light‐Emitting Diodes Based on Solution‐Processed WO _x Nanoparticles

Abstract Transition metal oxides, represented by tungsten oxides (WO x ), are considered as a potential candidate of hole injection materials for optoelectronic thin‐film devices to overcome the acidity and hygroscopicity of PEDOT:PSS. However, due to the lack of in‐depth study of materials and careful construction of film interfaces, the performance of as‐prepared quantum dot light‐emitting diodes (QLEDs) is generally not ideal, which limits the further development and research of this field. Here, solution‐processable WO x nanoparticles (WO x NPs) with excellent film‐forming properties are synthesized and introduced to solve this issue. Meanwhile, in situ photo‐induced ligand exchange enabled the robust interfaces of WO x films, expanding the selection of functional materials. The as‐prepared QLED devices achieved a peak external quantum efficiency (EQE) of 15.09%, representing one of the best performances for WO x ‐based QLEDs. Furthermore, high‐resolution WO x patterns (pixel size: ≈700 nm) through regional exposure were developed successfully, demonstrating the potential in future high‐resolution and high‐performance displays, and laying the foundation for the implementation of all inorganic QLEDs.