High Performance InP‐based Quantum Dot Light‐Emitting Diodes via the Suppression of Field‐Enhanced Electron Delocalization

Abstract To understand the exciton dynamics due to the electron delocalization in InP‐based quantum dot light‐emitting diodes (QLEDs), the exciton dynamics are systematically controlled in InP‐based QLEDs through varying the shell thicknesses of InP/ZnSe quantum dots (QDs) and the effective electrical field (E‐field) across the QDs. It is found that the field‐independent energy transfer is effectively suppressed as the shell thickness increases. However, InP/ZnSe QDs with thicker shells only have limited benefit for suppressing the exciton transfer due to field‐enhanced electron delocalization in films on electron transport layers or working devices. The field‐assisted exciton transfer is mainly driven by the large E‐field and field‐enhanced electron delocalization in InP/ZnSe QDs. External quantum efficiency of 22.56% is achieved in InP‐based QLEDs by reducing the effective E‐field (at 2 V bias). The breakthrough luminance of 136 090 cd/m −2 is achieved at a large bias of 7.2 V, due to the suppression of field‐enhanced electron delocalization by the ultra‐thick shell.