All-Solution-Processed Dual-Color QLED with Hole-Only-Injection and n-p-n Intermediate Connecting Layer

Quantum dot light-emitting diodes (QLEDs) are promising candidates for next-generation displays due to their high color purity and tunable emission wavelengths, but achieving high resolution in QLEDs remains a significant challenge. Adopting an alternative subpixel layout with dual-color emission devices is an emerging approach for achieving high resolution. In this report, we demonstrate an all-solution-processed dual-color emission QLED using a hole-only injection (HOI) and an n-p-n intermediate connecting layer. These devices enable either selective emission from the emission layer (EML) or mixed colors using pulse-width modulation (PWM) driving. The n-p-n intermediate connecting layer shows superior charge generation and transport compared with previously reported p-p⁺-p structures. We fabricated green-red, blue-red, and blue-green dual-color devices that generate full-color output by mixing two EMLs, potentially increasing display resolution while maintaining subpixel size and count. The devices exhibit luminance values of 8225.6, 4096.9, and 307.3 cd/m² for pure green, red, and blue emissions, respectively. Using PWM operation, we achieve various mixed colors covering 84.14% of the Rec.2020 standards color gamut. Our approach offers a promising solution for high-resolution displays with enhanced color performance, particularly beneficial for applications demanding high pixel densities.