A 320 nm thick surfactant-templated nanoporous (STN) TiO2 layer prepared from block copolymer P123 [poly(ethylene oxide)20-poly(propylene oxide)70-poly(ethylene oxide)20] was used as an interlayer between a 21 μm thick mesoporous TiO2 layer and a transparent conducting oxide. The thin STN TiO2 interlayer had well-dispersed nanoporous features, which made it possible to adsorb dye molecules in the interlayer. In addition, it provided an enhanced electron lifetime, resulting in a reduced recombination rate and an increased diffusion length. The dye-sensitized solar cell with the thin STN interlayer resulted in a significantly increased overall energy conversion efficiency from 7.11% to 9.22% with an improvement of all parameters (short-circuit current, open circuit voltage, and fill factor).