Functionalized terfluorene for solution-processed high efficiency blue fluorescence OLED and electrophosphorescent devices

Abstract

A new multifunctional blue-emitting terfluorene derivative (TFDPA) featured with triphenylamine groups for hole-transportation and long alkyl chains for solution processability on the conjugation inert bridge centers was reported. TFDPA can give homogeneous thin film by solution process and exhibits high hole mobility (μh≈10−3cm2V−1s−1) and suitable HOMO for hole injection. Particularly, TFDPA performs efficient deep-blue emission with high quantum yield (∼100% in solution, 43% in thin film) and suitable triplet energy (ET=2.28eV), making solution-processed OLED devices of using TFDPA as blue emitter and as host for iridium-containing phosphorescent dopants feasible. The solution-processed nondoped blue OLED device gives saturated deep-blue electroluminescence [CIE=(0.17, 0.07)] with EQE of 2.7%. TFDPA-hosted electrophosphorescent devices performed with EQE of 6.5% for yellow [(Bt)2Ir(acac)], 9.3% of orange [Ir(2–phq)3], and 6.9% of red [(Mpq)2Ir(acac)], respectively. In addition, with careful control on the doping concentration of [(Bt)2Ir(acac)], a solution-processed fluorescence–phosphorescence hybrided two-color-based WOLED with EQE of 3.6% and CIE coordinate of (0.38, 0.33) was successfully achieved.