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 ‐WX 2 ( n =2.7, 2.9; X=S, Se) heterostructures by sulfurization or selenization of WO n nanomaterials. The WO n ‐WX 2 heterostructures are composed of WO 2.9 nanoparticles (NPs) or WO 2.7 nanowires (NWs) grown together with single‐ or few‐layer WX 2 nanosheets (NSs). As a proof‐of‐concept application, the WO n ‐WX 2 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‐WSe 2 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.