Fabrication of QLED Devices with Designable Patterns via Regulating the Carrier Transport Behavior

The burgeoning advancements in near-eye display devices intensify attention to ultra-high-resolution display technology. Due to the outstanding properties including high color purity, low turn-on voltage, solution processability, etc., quantum dot light-emitting diodes (QLEDs) are among the most promising candidates for next-generation displays. This study proposes a novel strategy to construct QLED devices with designable patterns by adjusting the energy level alignment and corresponding carrier transport behavior. As a proof-of-concept, patterned hole injection layers (HIL) based on photosensitive poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite are prepared by direct photolithography. Noteworthily, the red QLED devices with optimized photolithographic HIL exhibit an increased external quantum efficiency, from 17.2% to 18.4%, and an extended operational lifetime (T₉₅ at 1,000 cd m^-2), from 471 to 827 h. Subsequently, three primary color QLED devices with above 3,300 DPI (dot per inch) are successfully achieved by utilizing pixelated HIL, paving the technical foundation for developing ultra-high resolution QLED displays.