title: Enhanced Electron Affinity and Exciton Confinement in Exciplex-Type Host: Power Efficient Solution-Processed Blue Phosphorescent OLEDs with Low Turn-on Voltage.
abstract: A benzimidazole/phosphine oxide hybrid 1,3,5-tris(1-(4-(diphenylphosphoryl)phenyl)-1H-benzo[d]imidazol-2-yl)benzene (TPOB) was newly designed and synthesized as the electron-transporting component to form an exciplex-type host with the conventional hole-transporting material tris(4-carbazoyl-9-ylphenyl)amine (TCTA). Because of the enhanced triplet energy and electron affinity of TPOB, the energy leakage from exciplex-state to the constituting molecule was eliminated. Using energy transfer from exciplex-state, solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) achieved an extremely low turn-on voltage of 2.8 V and impressively high power efficiency of 22 lm W(-1). In addition, the efficiency roll-off was very small even at luminance up to 10 000 cd m(-2), which suggested the balanced charge transfer in the emission layer. This study demonstrated that molecular modulation was an effective way to develop efficient exciplex-type host for high performanced PHOLEDs.
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China.
authors.forename: Xinxin
authors.initials: X
authors.lastname: Ban
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China.
authors.forename: Kaiyong
authors.initials: K
authors.lastname: Sun
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China.
authors.forename: Yueming
authors.initials: Y
authors.lastname: Sun
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Huang
authors.affiliation: School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
keywords: blue emission; exciplex; organic light emitting diode; solution-process; turn-on voltage