Color-tunable top-emitting OLEDs via pixelated dual-microcavity design

This study introduces a color-tunable organic light-emitting diode architecture based on a pixelated dual-microcavity design, fabricated using a single-layer mask technique. The device is engineered by vertically stacking a pixelated yellow emissive layer (EML) matrix onto a continuous, large-area blue EML. This configuration enables independent optical control of the blue and yellow emissions, resulting in narrowband spectra and high color purity that surpass the spectral modulation limitations inherent in conventional single-microcavity structures. To achieve near-monochromatic emission, a hole-dominant host was selected for the blue EML, while a bipolar host was employed for the pixelated yellow EML. A critical thickness differential between the regions with and without the yellow EML induces a distinct evolution in the intensity of blue and yellow emissions as a function of applied voltage. By exploiting voltage-driven carrier dynamics, the device exhibits continuous tuning of the International Commission on Illumination (CIE) coordinates from (0.19, 0.28) to (0.40, 0.47), thereby demonstrating outstanding and broadly controllable color gamut modulation.