A series of alcohol soluble amino-functionalized carbazole-based copolymers were synthesized via Suzuki coupling reaction. The pendent amino groups endow them high solubility in polar solvents, as well as efficient electron injection capability from high work-function metals. The relationships between the photophysical and electrochemical properties and the polymer backbone structure were systematically investigated. These alcohol-soluble carbazole-based copolymers were used as cathode interlayers between the high work-function metal A1 cathode and P-PPV emissive layer in polymer light-emitting diodes with device structure of ITO/PEDOT：PSS/P-PPV/interlayer/A1. The resulting devices exhibited improved performance due to the better electron injection/transporting ability of the designed copolymers from A1 cathode to the light-emitting layer.
Four new 2D donor–acceptor conjugated polymers were designed and synthesized.These new polymers comprised fluorenealt-triphenylamine or carbazole-alt-triphenylamine as the backbones,and pendants with 2,1,3-benzothiadiazole(BT)or naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole(NT)in a triphenylamine unit as the side groups.By changing the acceptor BT for a stronger electron-withdrawing unit of NT moiety in the side chain,the energy levels,absorption spectra,band gaps,and charge-transport abilities of the resultant polymers could be effectively tuned.Bulk heterojunction solar cells with these polymers as the electron donors and(6,6)-phenyl-C71-butyric acid methyl ester as the electron acceptor exhibited high open-circuit voltage(more than 0.8 e V).The power conversion efficiency can be improved from 1.37%to 3.52%by replacing the BT with an NT moiety,which indicates that introducing NT as the side-chain building block can be an effective strategy to construct efficient 2D conjugated polymers for PSCs.
Wei LiQingduan LiShengjian LiuChunhui DuanLei YingFei HuangYong Cao
