Highly Efficient Multifunctional Luminogens for Near UV/Deep Blue (CIE_y ∼0.02) and Hybrid White OLEDs (CIE ∼0.33, 0.37) with Superior Color Stability

Near-ultraviolet (NUV) light-emitting pure organic fluorophores are crucial in organic electronics because of less power consumption and full-color displays with a wide color gamut. However, emerging solution-processable NUV emitters for violet organic light-emitting diodes (VOLEDs) is quiet a formidable task. On this basis, two efficient NUV/deep blue N,N-diphenyl-3′-(1-(3-(trifluoromethyl)phenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)-[1,1′-biphenyl]-4-amine (3-PIMCFTPA) and 3′-(4,5-diphenyl-1-(3-(trifluoromethyl)phenyl)-1H-imidazol-2-yl)-N,N-diphenyl-[1,1′-biphenyl]-4-amine (3-BICFTPA) emitters were designed and synthesized based on a meta-linking D−π–A design strategy, which efficiently shortens the π-conjugation length, which results emission in the higher energy end of the emitters. Experimental and theoretical investigation reveals materials with efficient NUV emission and good bipolar carrier transporting properties. Hence, the undoped, as well as doped OLED devices, were fabricated utilizing our synthesized fluorophores. Among them, 3-PIMCFTPA showed the best electroluminescence performance with maximum external quantum efficiency (EQEmax) of 5.7 and 3.4% with Commission Internationale d'Énclairage (CIE) coordinates of (0.17, 0.10) and (0.17, 0.02), respectively. Moreover, the 3-PIMCFTPA possesses a pure violet emission (385 nm) with high performance, allowing the emitter to be used to realize high-performance hybrid white OLEDs. The 1 wt% yellow emitter-based device displayed pure white light with a PEmax of 22.5 lm W–1, a CEmax of 25.4 cd A–1, and an EQEmax of 12.0% with a CIE coordinate (0.33, 0.37) at 1000 cd m–2. These results of our emitters make them potential for smart displays and lighting applications.