White organic light-emitting diodes based on a single-emissive layer using electrophosphorescent dopants in a fluorescent host

Abstract

A single-emissive fluorescent layer co-doped with red and blue phosphorescent dyes in a host [4, 4, bis-9 carbozyl-biphenyl] (CBP) was used to fabricate white organic light-emitting devices (WOLEDs). The electroluminescent spectrum of the generated white light was observed to have two spectral peaks at ∼495 and ∼590 nm and a dip at ∼ 536 nm, with different thicknesses of the emissive layer (EML). By optimizing the ratio of the dopants in the EML, the ratio of the maximum intensity of the two spectral peaks was brought to unity. The Commission Internationale de l'Eclairage (CIE) coordinates and correlated color temperature of the fabricated device were calculated, and the results are reported herein. No significant change in the spectral shape of the emission spectra and the CIE coordinates were obtained when the applied voltages were varied. It is easier to fabricate WOLEDs with a single EML as compared with their multilayer counterparts.