Robust tetrakisarylsilyl substituted spirobifluorene: Synthesis and application as universal host for blue to red electrophosphorescence

Abstract

Stable hosts with high triplet energy levels are of great importance for achieving highly efficient phosphorescence organic light-emitting diodes (PhOLEDs). In this work, a simple and robust spirobifluorene derivative peripherally substituted with tetrakisarylsilyls was designed and synthesized. The spirobifluorene derivative exhibits high thermal/morphological stabilities and ultra-violet blue emissions with moderate fluorescence quantum yields. DFT calculation indicates that the frontier molecular orbitals (FMOs) are mainly associated with the spirobifluorene segment and there is very limited distribution on the peripheral substituents. PhOLEDs using TPSiF as a universal host were fabricated and blue to red emissions were achieved with high efficiencies, among which the green device using Ir(ppy)2acac as guest showed high performance with maximum luminance, current efficiency, power efficiency and external quantum efficiency (EQE) of 11690 cd m−2, 77.2 cd A−1, 47.3 lm W−1, and 21.1%, respectively. Notably, the blue devices show excellent efficiencies at high doping concentration and a 14.9% EQE was achieved at 30 wt % dopant with maximum luminance, current efficiency and power efficiency of 7782 cd m−2, 36.0 cd A−1 and 29.8 lm W−1, respectively.