Synthesis and optical properties of copolymers containing carbazole and 1,3,4-oxadiazole groups as blue host matrix and charge transport materials for polymer light emitting devices

Abstract

Alternating copolymers with N-arylcarbazole as hole injection and transport moieties with blue emission and 1,3,4-oxadiazole as electron transporting and hole blocking moieties were synthesized by Pd-catalyzed polycondensation reaction, and named as poly[N-(4-aminophenyl)-carbazole-alt-N-(2-ethylhexyl)-3, 6-carbazole] (P1), poly[N-(4-aminophenyl)-carbazole-alt-2,5-bis(4-phenyl)-1,3,4- oxadiazole] (P2) and poly[N-(4-aminophenyl)-carbazole-alt-2,5-bis(4- methylenephenyl)-1,3,4-oxadiazole] (P3). It was observed that UV-Vis absorption spectra showed two main peaks at 290295 and 310380 nm and maximum photoluminescence peaks of the polymers were all in the range of blue light emission from 418 to 453nm. It appeared that optical and electrochemical properties of polymers such as HOMO, LUMO levels and band gap energy could be fine tuned by chemical modification of polymer structures.