Micro-LED and OLED Hybrid Devices for Application as Full-color Display Pixels

Micro light-emitting-diodes (Micro-LEDs), as core components of next-generation displays, offer high brightness, low power consumption, long lifespan, and fast response. However, the commercial development of red and green Micro-LEDs is hindered by low quantum efficiency and immature mass transfer technology. Meanwhile, although organic light-emitting diodes (OLEDs) have achieved stable commercial application with red and green phosphorescent materials, blue phosphorescent OLEDs still suffer from insufficient luminous efficiency and short device lifetime. To overcome these limitations, this study proposes a novel full-color display design by integrating blue Micro-LEDs with red and green OLEDs in a single passive-driven matrix, eliminating the need for mass transfer. Passive matrix devices with two different mesa sizes were fabricated on a 4-inch blue epitaxial wafer. A series-parallel sub-pixel structure was adopted, which effectively reduces electrode wiring complexity while significantly improving pixel density. In this study, we conducted photoelectric tests on the two different mesa - sized blue Micro-LEDs and red and green OLEDs. The turn-on voltage of the blue Micro-LEDs was 2.7 V, while that of the red and green OLEDs was 3.0 V—values close enough to allow simultaneous illumination under the same driving circuit. At a voltage of 4.5 V, the luminance of the 20×70 μm² blue Micro-LED reached 3.08×10⁴ cd/m², while that of the 40×90 μm² blue Micro-LED achieved 3.69×104 cd/m². At 5 V, the luminance of the 50×70 μm² green OLED reached 87.37 cd/m², the 70×90 μm² green OLED reached 100.13 cd/m², the 50×70 μm² red OLED reached 18 cd/m², and the 70×90 μm² red OLED reached 28.1 cd/m².