Improvement of external quantum efficiency depressed by visible light-absorbing hole transport material in solid-state semiconductor-sensitized heterojunction solar cells.

A mesoporous (mp)-TiO(2)/Sb(2)S(3)/P3HT [poly(3-hexylthiophene)] heterojunction solar cell displays reduced external quantum efficiency (EQE) at a wavelength of approximately 650 nm. This loss in EQE is due to incomplete charge carrier transport because the transportation of charge carriers generated in P3HT by the absorption of light into Sb(2)S(3) was inefficient, and consequently, the carriers recombined. The depression of the EQE was greatly relieved by introducing the porous structure formed by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) into the P3HT layer.