Hybrid Tandem White Light-Emitting Diodes Based on GaN and Organic Emitters

Tandem white organic light-emitting diodes (OLEDs), formed by stacking red, green, and blue organic electroluminescent units, offer a promising route toward high-resolution microdisplays. However, their performance is constrained by the intrinsically short lifetime of blue OLED sub-units. Replacing the unstable blue OLED with a long-lived GaN-based LED could address this limitation, but practical hybridization remains difficult because of incompatible fabrication routes and significant current imbalance between the inorganic and organic units. Here, we demonstrate the first hybrid GaN-OLED tandem white LEDs enabled by an interface-engineered charge-generation unit (CGU). By introducing an ITO/HAT-CN/LiNH₂-doped Bphen CGU, we simultaneously enhance the work function, strengthen the built-in electric field, and smooth the interfacial morphology. These synergistic effects promote efficient charge generation, yielding near-ideal voltage summation and well-balanced electron-hole injection. As a result, the hybrid tandem device shows a nearly twofold increase in current efficiency (from 28.1 to 58.6 cd A^-1) and significantly reduced spectral shift under varying current densities. We further demonstrate the generality of this approach by integrating the GaN emission with yellow OLEDs to produce stable blue-yellow hybrid white emission. This work establishes an applicable strategy for integrating GaN-LEDs and OLEDs, opening a pathway toward efficient, stable, and compact white light engines for next-generation microdisplay technologies.