Nanoimprinted DMD Electrodes Enabling Bidirectional Viewing OLEDs With Quasi Lambertian Emission.

Bidirectional displays, capable of simultaneous front and rear illumination, enable transformative applications such as see-through retail displays, intelligent signage, and next-generation foldable devices. Despite their potential, the inherent trade-off between transparency and brightness, coupled with imbalanced bidirectional emission, has hindered the advancement of bidirectional viewing organic light-emitting diodes (BV-OLEDs). Here, we present a dual-approach strategy to achieve simultaneously improved and balanced bidirectional emission with quasi-Lambertian distribution in bidirectional emitting OLEDs. By combining a microcavity resonance enhancement through nano-patterned structures and a dielectric/metal/dielectric (DMD) capping layer for improved top electrode transmittance, we effectively suppress surface plasmon and waveguide modes in OLED devices. Consequently, the optimized nanoimprinted DMD electrode achieved a remarkable 89.7% enhancement in transmittance (from 33.9% to 64.3% at 664 nm) compared to conventional planar electrodes; and the resulting BV-OLED demonstrated balanced bidirectional emission from 33% to 42% with a 67.3% total brightness increase, while exhibiting enhanced transparency with nearly zero haze, quasi-Lambertian radiation pattern, and excellent color stability across a 120° viewing angle. This breakthrough establishes a fundamental design framework for bidirectional displays, bridging conventional dual-panel technologies with emerging applications in next-generation transparent and flexible display systems.