High performance deep-blue organic light emitting diodes via excited state regulation of phenanthroimidazole-triazole derivatives. (October 2022)

• Record Type: Journal Article
• Authors: Peng, Ling; Lv, Jichen; Huo, Yumiao; Hua, Lei; Liu, Yuchao; Ying, Shian; Yan, Shouke
• Is Part Of: Dyes and pigments. Volume 206(2022)
• Publication Date: 2022-10
• Subjects: Deep-blue fluorescent materials -- Organic light emitting diodes -- phenanthroimidazole−triazole derivatives -- Hybridized local and charge transfer -- Exciton utilization efficiency; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2022.110676
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Efficient deep-blue organic light emitting diodes (OLEDs) have always been of great interest for both academia, and industry. Here, we reported facilely available phenanthroimidazole-triazole derivatives PITZF and PITZtCz with hybridized local and charge transfer states (HLCT) characteristics and investigated the effect of assistant terminal groups on the excited states and electroluminescence properties. Both fluorophores showed a remarkable thermal stability with a thermal decomposition temperature of over 400 °C. Compared with PITZF, the introduction of 3, 6-di- tert -butylcarbazole (tCz) assistant donor in PITZtCz boosted a fine modulation of excited state with an elevated locally excited (LE) compound and more efficient charge transfer (CT) transition in the high lying excited state, which contributes to a more efficient exciton utilization efficiency (EUE). The resulting doped OLEDs provided highlighted maximum EQE of 7.21% and low efficiency roll-off without sacrificing the color purity. The deep-blue emission was found with CIE coordinate of (0.158, 0.050), which is very close to the blue standard of Rec.2020. Graphical abstract: Image 1 Highlights: Novel phenanthroimidazole-triazole fluorophores with different assistant terminal groups were designed and synthesized. The deep-blue emission with CIE coordinates of (0.158, 0.050) was achieved. The doped device based on PITZtCz exhibited the maximum EQE of 7.21% and low efficiency roll-off.