Enhanced Red Color Conversion via Mixing Green and Red Quantum Dots in a Polydimethylsiloxane-Based Color Conversion Layer

Quantum dot (QD) color conversion technology has attracted considerable attention in QD-OLED displays because it enables the generation of highly pure red and green emissions from blue OLED excitation with reduced fabrication complexity. Mixed QD color conversion layers consisting of red and green QDs dispersed in a polydimethylsiloxane matrix were fabricated to improve red color conversion efficiency and suppress blue leakage. The color conversion characteristics of the mixed QD layers were investigated by varying the QD contents and layer thicknesses. The color conversion spectra, blue leakage characteristics, color conversion efficiency, and output/input efficiency were systematically analyzed. Compared with red QD-only layers, the mixed QD layers exhibited more effective suppression of blue leakage and stronger red emission even at relatively small layer thicknesses. The red QD-only layer containing 100 mg of red QDs exhibited a color conversion efficiency of 16.7% at a thickness of 38 µm, whereas the mixed QD layer with the same red QD content achieved a higher color conversion efficiency of 19.3% at a thickness of only 5.6 µm. The enhanced color conversion efficiency of the mixed QD layers is likely associated with increased absorption of blue photons and additional excitation of red QDs through photon reabsorption and possible energy transfer processes between the green and red QDs.