Synthesis of WOn‐WX2 (n=2.7, 2.9; X=S,Se) Heterostructures for Highly Efficient Green Quantum Dot Light‐Emitting Diodes

Preparation of two‐dimensional (2D) heterostructures is important not only fundamentally, but also technologically for applications in electronics and optoelectronics. Herein, we report a facile colloidal method for the synthesis of WO_n ‐WX₂ (n =2.7, 2.9; X=S, Se) heterostructures by sulfurization or selenization of WO_n nanomaterials. The WO_n ‐WX₂ heterostructures are composed of WO_2.9 nanoparticles (NPs) or WO_2.7 nanowires (NWs) grown together with single‐ or few‐layer WX₂ nanosheets (NSs). As a proof‐of‐concept application, the WO_n ‐WX₂ heterostructures are used as the anode interfacial buffer layer for green quantum dot light‐emitting diodes (QLEDs). The QLED prepared with WO_2.9 NP‐WSe₂ NS heterostructures achieves external quantum efficiency (EQE) of 8.53 %. To our knowledge, this is the highest efficiency in the reported green QLEDs using inorganic materials as the hole injection layer.