Efficient donor-acceptor host materials for green organic light-emitting devices: non-doped blue-emissive materials with dual charge transport properties.

ABSTRACT: Comparative optical, electroluminescence and theoretical studies were performed for (E)-4'-(1-(4-(2-(1-(4-morpholinophenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)vinyl)phenyl)-1H-phenanthro[9,10-d]imidazol-2-yl)-N,N-diphenyl-[1,1'-biphenyl]-4-amine (SMPI-TPA) and (E)-4-(4-(2-(4-(2-(4-(9H-carbazol-9-yl)phenyl)-1H-phenanthro[9,10-d]imidazol-1-yl)styryl)-1H-phenanthro[9,10-d]imidazol-1-yl)phenyl)morpholine (SMPI-Cz). These compounds show excellent thermal properties, dual charge transport properties and form thin films under thermal evaporation. Blue OLEDs (CIE: 0.16, 0.08) based on SMPI-TPA show efficient device performance (η _ex 6.1%; η _c 5.3 cd A^-1; η _p 5.2 lm W^-1) at low turn-on voltages. Both SMPI-TPA and SMPI-Cz were utilised as hosts for green OLEDs. The devices with SMPI-Cz (30 nm):5 wt% Ir(ppy)₃ exhibit maximum luminance of 20 725 cd m^-2, and η _c and η _p values of 61.4 cd A^-1 and 63.8 lm W^-1, respectively. In comparison, devices with SMPI-TPA (30 nm):5 wt% Ir(ppy)₃ exhibit high η _c and η _p values of 65.2 cd A^-1 and 67.1 lm W^-1, respectively. Maximum η _ex values of 19.6% and 23.4% were obtained from SMPI-TPA:Ir(ppy)₃ and SMPI-Cz:Ir(ppy)₃, respectively. These device performances indicate that the phenanthroimidazole unit is a tunable building unit for efficient carrier injection and it may also be employed as a host for green OLEDs.

SUBMITTER: Jayabharathi J 

PROVIDER: S-EPMC9080778 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature