High-Brightness Color-Tunable AC-Driven Quantum Dot Light-Emitting Diodes for Integrated Passive High-Electric-Field Contactless Detection

This work explores the carrier recombination dynamics of AC-driven quantum dot (QD) light-emitting diodes (AC-QLEDs) and proposes their application in the field of electric field contactless detection. Different sequences of green QD (GQD)/red QD (RQD) bilayer thin films as the emission layer of AC-QLEDs were fabricated via film transfer printing to ensure the complete morphology of each layer. AC-QLEDs with the emission layer as the sequence of GQD + RQD (GR-QLEDs) show a significantly enhanced carrier recombination efficiency due to its stable energy level structure, achieving the highest peak brightness ever recorded for vertically emitting brightness of 1648.2 cd/m2 depending on the carriers generated inside the device under AC bias. Owing to an imbalance in the carrier concentration generated by two sides of the emission layer, the proportion of emitted green light changes with the electric field strength, resulting in a macroscopic color shift of GR-QLEDs. The results indicate that although no carriers are injected directly from two electrodes, the equilibrium-induced carrier concentration under the AC electric field remains important. We utilized this unique device structure and color shift of GR-QLEDs for on-site inspection of large-scale communications power consumption. The patterned detector displays a significant color change from 9 × 106 to 6 × 107 V/m. True noncontact direct visualization detection was conducted under variable electric fields from 1 × 107 to 2 × 107 V/m in the vicinity of the running cable by emitting bright light. The proposed passive electric field detector is well-suited for investigating air gap discharge and monitoring spatial electric fields, featuring high integration, transparency, lightweight characteristics, high sensitivity, and broad bandwidth.