A highly efficient violet-blue OLED with Rec.2020 CIEy based on an orthogonal phenanthroimidazole-substituted 1, 2, 4-triazole derivative. Issue 25 (21st June 2022)

• Record Type: Journal Article
• Authors: Peng, Ling; Huo, Yumiao; Hua, Lei; Lv, Jichen; Liu, Yuchao; Ying, Shian; Yan, Shouke
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 25(2022)
• Page Start: 9621
• Page End: 9627
• Publication Date: 2022-06-21
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc01280d
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A violet-blue OLED derived from an orthogonal phenanthroimidazole-substituted 1, 2, 4-triazole fluorophore achieved a high EQE of 6.01% and CIE y of 0.043, being close to the blue standard of Rec.2020. Abstract : It has been challenging to achieve high efficiency and low roll-off violet-blue OLEDs with the Commission Internationale de l'Eclairage (CIE) coordinates matching the blue-light standard of ultra-high definition televisions (UHDTVs) ITU-R BT.2020. Herein, a novel triazole (TAZ)-based hybrid local and charge transfer (HLCT) fluorophore, PI-TAZ-tbuCZ, has been successfully designed and synthesized by introducing the bulky phenanthroimidazole unit at the sp 3 hybrid N4 atom of TAZ. This not only improves the thermal stability, showing a high thermal decomposition temperature of 459 °C, but also limits the molecular conjugation length and intramolecular charge transfer, effectively guaranteeing short-wavelength emission. The resulting device exhibits a violet-blue electroluminescence emission with the peak wavelength of 407 nm, narrow full width at half-maximum of 52 nm and CIE coordinates of (0.160, 0.043). Notably, a maximum external quantum efficiency of 6.01% is achieved, and the value still keeps as high as 5.10% at 500 cd m −2, showing a small efficiency roll-off. These results illustrate that PI-TAZ-tbuCZ should be a promising fluorophore for violet-blue OLEDs.