Synthesis, characterization, and electrogenerated chemiluminescence of deep blue emitting eumelanin‐inspired poly(indoylenearylene)s for polymer light emitting diodes

Deep blue emitting copolymers were synthesized by uniting the Eumelanin-inspired indole core with fluorene and carbazole units via Suzuki polymerization. The resulting polymers, PIF and PIC, showed deep blue emission in the range of 416-418 nm and quantum yields of 0.39-0.60. Both polymers exhibited an intense and stable electrogenerated chemiluminescence. Interestingly, deep HOMO levels of -5.71 and -5.61 eV were observed for PIF and PIC, respectively. Solution processed polymer light emitting diodes (PLEDs) were fabricated using the PIF as a guest. PLEDs emitted deep blue light at 418 nm, with the luminous efficiency peaking at 1 Cd/A, given that the photopic response at that wavelength is 0.0151. The electroluminescence of PIF displayed a Commission Internationale de l'Eclairage coordinates of (0.16, 0.07) with a maximum external quantum efficiency of 1.1%. Hence, these materials prove to be promising candidates for the fabrication of deep blue PLEDs. (c) 2017 Wiley Periodicals, Inc.