Wide color gamut deep-blue OLED architecture for display application

Abstract

Organic light emitting diodes (OLEDs) are considered to be among the best flat panel display technologies owing to their wide viewing angle, wide color gamut, high speed response, high resolution, and simple structure. In order to enhance the realism, wide color gamut is of vital importance to all the display devices. Here, we demonstrate a wide color gamut, deep-blue OLED for the next generation high quality full-panel displays based on the lateral introduction of the cyano group on a local excited (LE) chromophoric axis, which significantly affects the nature of the excited state and leads to the optimal hybridization local and charge transfer states (HCLT). Most notably, OLED based on the HLCT molecule (C4) showed more than two-fold increment in the external quantum efficiency (EQE) and uncompromised color purity as compared to a molecule (CI), which lacks cyano group and possesses LE state. The engineered molecular design features cross-conjugated localized and charge-transfer chromophores which result in a hybridized local charge transfer (HLCT) excited state. OLED using this material presented greater than 6.5% external quantum efficiency with excellent color saturation (CIEy -0.058) and small full-width at half maximum (46nm). Additionally, the resultant deep blue emission achieved 99, 101, 101, 100, and 96 % color saturation compared with the sRGB, NTSC, Adobe RGB, HDTV ITU-R BT.709-5, and Rec. 2020 standards, respectively.