Enhanced photovoltaic properties by device optimization of benzotriazole-containing conjugated polymers

We prepared three D-pi-A conjugated polymers consisting of a benzotriazole building block as an acceptor. Carbazole, fluorene, and benzodithiophene units were utilized for electron donors in the conjugated backbones to form PBTZCZ, PBTZFL, and PBTZSP, respectively. Their structural, thermal, optical, and photovoltaic properties were investigated. After optimizing device processing conditions for conventional bulk-heterojunction solar cells, we could achieve a highest PCE of 2.43% with J(sc) of 6.58 mA/cm(2), V-oc of 0.74 V, and FF of 49.2% for PBTZCZ:PC60BM. Further improvement could be accomplished by inverted solar cell devices showing the PCE of 3.81% with J(sc) of 7.69 mA/cm(2), V-oc of 0.88 V, and FF of 55.9%.