A novel, bipolar host based on triazine for efficient solution-processed single-layer green phosphorescent organic light-emitting diodes

Abstract

A novel N-phenyl carbazole substituted 2, 4,6-trisphenyl-triazine host material(TPCPZ) for solution processed green phosphorescent organic light-emitting devices (PhOLEDs) was synthesized by a Suzuki-cross coupling reaction. The optical, electrochemical and thermal properties of TPCPZ have been characterized. TPCPZ exhibits a high glass transition temperature of 165 °C and a triplet energy of 2.63 eV. The appropriate HOMO energy level (−5.39 eV) and LUMO energy level (−2.16 eV) matching with the HOMO energy level of PEDOT:PSS(−5.35 eV) and the LUMO energy level of Cs2CO3/Al bilayer cathode (−2.2 eV), facilitate the transfer of holes and electrons. The solution-processed single-layer device using TPCPZ as the host for fac-tris(2-(4-phenylpyridine)iridium (Ir(ppy)3) exhibited a low turn-on voltage of 3.5 V, a maximum current efficiency of 20.8 cd A−1 and a maximum luminance of 18,000 cd m−2. These results demonstrated that TPCPZ as a host material is advantageous for fabrication of highly efficient single-layer green PhOLEDs.