Synthesis of dibenzofuran and dibenzothiophene derivatives as yellow host materials for phosphorescent organic light-emitting diodes

Novel host materials containing dibenzofuran and dibenzothiophene, (5-(8-(9H-carbazole-9-yl)dibenzo[b,d] furan-2-yl)thiophene-2-yl)diphenylphosphine oxide (3, CFTPO) and (5-(8-(9H-carbazol-9-yl)dibenzo[b,d]thiophen-2-yl)thiophen-2-yl)diphenylphosphine oxide (4, CTTPO) were synthesized and employed as yellow host materials. The CFTPO host material had bipolar characteristics because it contained carbazole, dibenzofuran, and diphenylphosphine oxide charge transport units with triplet energy (2.56 eV), high external quantum efficiency (24.4%), and power efficiency (63.4 lm/W) in a yellow phosphorescent device. The CTTPO host material also had bipolar characteristics because it contained carbazole, dibenzothiophene, and diphenylphosphine oxide charge transport units with triplet energy (2.52 eV), high quantum efficiency (25.4%), and power efficiency (65.7 lm/W) in a yellow phosphorescent device.