Hybrid color-conversion layers for white emission from fluorescent blue organic light-emitting diodes

Hybrid color-conversion layers (CCLs) were developed to convert a blue emission from fluorescent organic light-emitting diodes (OLEDs) to obtain a white emission with a high color rendering index (CRI). The hybrid CCLs were composed of an inorganic phosphor, organic dye, and silicon dioxide (SiO2) scattering nanoparticles. The inorganic phosphors convert a part of blue emission from OLEDs to a green yellow emission effectively. A part of the green-yellow emission was consecutively converted to a red emission with the organic dye. Using the hybrid CCLs, we obtained a balanced white emission with the highest CRI of 93 and the color temperature of 3500 K. The high CRI white OLED showed the power efficiency of 11 lm/W which was enhanced by 1.9 times from that of the blue fluorescent OLED. We showed that the utilization of the SiO2 nanoparticles did not only enhance the power efficiency but also significantly reduce the white color variation to the viewing angle. (C) 2017 Elsevier B.V. All rights reserved.