Dipole-assisted functionalization enables long-range ordering of ZnTeSe quantum dots for efficient and stable deep-blue electroluminescence
摘要
Cadmium (Cd)- and lead (Pb)-free quantum dot light-emitting diodes (QD-LEDs) are critical for next-generation, environment-friendly electroluminescent displays. However, Cd/Pb-free QD-LEDs remain severely limited in operational stability, particularly in the deep-blue region. For emission below 460 nm, the high hole injection barrier inhibits carrier balance, thus requiring high bias to reach practical levels of luminance. Here we develop a dipole-assisted strategy to enable long-range ordering and energy adjustment of ZnTeSe QDs—achieved via the surface reconstruction using 4-aminothiophenol—to reduce the hole barrier in the deep-blue region. The intramolecular dipole deriving from the aromatic-bridged amine and thiol moieties of 4-aminothiophenol ensures the ordering arrangement of QD films and reduces the energy between the vacuum and the Fermi level, leading to the upshift of both valence and conduction band without affecting the deep-blue emission. As a result, devices emit at 452 nm with a peak external quantum efficiency of 23.6% at luminance values of 800 cd m−2 and maintain an external quantum efficiency of 22% at 1,000 cd m−2. Moreover, our LEDs achieve a calculated operational half-lifetime exceeding 50,000 h at an initial luminance of 100 cd m−2. Our results establish a benchmark for eco-friendly QD-LEDs towards practical applications in display technologies.