Thermal-Induced Hole-Current Reinforcement in Quantum Dot Light-Emitting Diodes

Quantum dot light-emitting diodes (QLEDs) exhibit pronounced thermal- and size-dependent charge injection, characterized by significantly enhanced current under elevated temperatures and reduce device areas. In this study, the underlying mechanisms are elucidated by examining the influence of thermal energy on carrier transport dynamics. This analysis reveals that hole transport is governed by a hopping mechanism, leading to markedly increased hole mobility at higher temperatures, which is a primary contributor to the thermal-dependent current enhancement. This improved hole injection promotes better charge balance and increase luminance. Furthermore, both thermal effect and lateral resistance is identified as key contributors to the size-dependent current behavior. Smaller-area QLEDs exhibit reduced lateral resistance and more pronounced thermal effect, resulting in higher current injection. By leveraging these thermally and geometrically enhanced hole injection characteristics, the application of QLEDs is demonstrated as multi-dimensional visual temperature sensors and realize significantly stronger emission from high-energy excitonic state (1P) transitions in small-area devices.