Advances on Transparent Top-Electrode for High-Performance Top-Emitting Quantum Dot Light-Emitting Diodes

Top-emitting quantum dot light-emitting diodes (TQLEDs) offer a promising device structure for next-generation displays by effectively addressing aperture ratio limitations and enabling more efficient light utilization in backplane-integrated displays compared with bottom-emitting QLEDs. To date, various top-electrode materials have been developed for high-performance TQLEDs, which are primarily fabricated via nonsolution processes depending on their intrinsic material properties. In this review, we systematically summarize recent progress on several representative transparent top electrodes, including Ag-based, conductive oxides-based electrodes patterned by vacuum evaporation or magnetron sputtering using shadow masks, and emerging Ag nanowire (AgNW)-based electrodes with desired micropatterns by solution processing, with a particular emphasis on how their optical properties and structural designs modulate light outcoupling behavior. Beyond their optical modulation of light outcoupling, their electrical, processing, and reliability characteristics are comparatively discussed, with particular attention to the practical integration of prospective AgNW-based electrodes in high-resolution TQLEDs. On this basis, we further suggest the perspectives of top electrodes, including multifunctional structural integration, wavelength-dependent design, application-oriented design and application-specific quantitative targets, aiming to provide guidance for the development of high-performance TQLEDs.