High‐performance white OLEDs with high color‐rendering index for next‐generation solid‐state lighting

Abstract— Several white-OLED structures with a high color-rendering index (CRI) were investigated for lighting applications. A two-unit fluorescent/phosphorescent hybrid white OLED achieved an excellent CRI of 95, high luminous efficacy of 37 lm/W, and long lifetime of over 40,000 hours at 1000 cd/m2. White-OLED lighting panels of 8 × 8 cm for high-luminance operation were fabricated, and a stable emission at 3000 cd/m2 was confirmed. Quite a small variation in chromaticity in a different directions was achieved by using an optimized optical device structure. With a light-outcoupling substrate, a higher efficacy of 56 lm/W, high CRI of 91, and longer half-decay lifetime of over 150,000 hours at 1000 cd/m2 was achieved. All-phosphorescent white OLEDs placed on the light-outcoupling substrate show a high CRI of 85 and higher efficacy of 65 lm/W with a fairly good half-decay lifetime of over 30,000 hours. With a further voltage reduction and a high-index spherical extractor, 128 lm/W at 1000 cd/m2 has been achieved.