A facile way to synthesize high-triplet-energy hosts for blue phosphorescent organic light-emitting diodes with high glass transition temperature and low driving voltage. (November 2015) - Wang, Ya-Kun
Abstract: Two novel bipolar host materials were designed and synthesized, by incorporating α-carboline and carbazole to spiro-acridine-fluorene skeleton. As expected, both materials exhibited high triplet energy over 2.8 eV, indicating they could act as suitable blue hosts in phosphorescent organic light-emitting diodes. By changing the appending group from carbazole to α-carboline, the thermal property and molecular bipolarity were improved. When they were applied as hosts for sky-blue emitter iridium(III) bis[4, 6-difluorophenyl]pyridinato-N, C2′ ] picolinate (FIrpic), good performance of 35.5 cd A −1, 35.8 lm W −1 and 29.5 cd A −1, 24.5 lm W −1 was achieved for α-carboline derivative and carbazole derivative, respectively. Graphical abstract: Highlights: Two spiro-fused host materials can achieve high triplet energies for blue electroluminescence. Both materials showed high glass transition temperatures over 180 °C. The derivatives on acridine of spiro-acridine-fluorene moiety are facilely achieved through simple synthetic step. The appending groups can influence the properties and corresponding device performance significantly under this derivation way.