High-Brightness Color-Tunable\nAC-Driven Quantum Dot\nLight-Emitting Diodes for Integrated Passive High-Electric-Field Contactless\nDetection

This work explores the carrier recombination dynamics\nof AC-driven\nquantum dot (QD) light-emitting diodes (AC-QLEDs) and proposes their\napplication in the field of electric field contactless detection.\nDifferent sequences of green QD (GQD)/red QD (RQD) bilayer thin films\nas the emission layer of AC-QLEDs were fabricated via film transfer\nprinting to ensure the complete morphology of each layer. AC-QLEDs\nwith the emission layer as the sequence of GQD + RQD (GR-QLEDs) show\na significantly enhanced carrier recombination efficiency due to its\nstable energy level structure, achieving the highest peak brightness\never recorded for vertically emitting brightness of 1648.2 cd/m<sup>2</sup> depending on the carriers generated inside the device under\nAC bias. Owing to an imbalance in the carrier concentration generated\nby two sides of the emission layer, the proportion of emitted green\nlight changes with the electric field strength, resulting in a macroscopic\ncolor shift of GR-QLEDs. The results indicate that although no carriers\nare injected directly from two electrodes, the equilibrium-induced\ncarrier concentration under the AC electric field remains important.\nWe utilized this unique device structure and color shift of GR-QLEDs\nfor on-site inspection of large-scale communications power consumption.\nThe patterned detector displays a significant color change from 9\n× 10<sup>6</sup> to 6 × 10<sup>7</sup> V/m. True noncontact\ndirect visualization detection was conducted under variable electric\nfields from 1 × 10<sup>7</sup> to 2 × 10<sup>7</sup> V/m\nin the vicinity of the running cable by emitting bright light. The\nproposed passive electric field detector is well-suited for investigating\nair gap discharge and monitoring spatial electric fields, featuring\nhigh integration, transparency, lightweight characteristics, high\nsensitivity, and broad bandwidth.