Block copolymer templated nanoporous TiO2 for quantum-dot-sensitized solar cells

Abstract

Nanoporous TiO₂ films were prepared on conductive fluorine-doped tin oxide (FTO) glass substrates using polystyrene-block-poly (ethylene oxide) (PS-b-PEO) copolymer as template. By optimizing the ratio of the template to titanium precursor, a TiO₂ film with uniform bicontinuous pore structure was obtained. The CdSe quantum dots (QDs) were in situ deposited on the nanoporous TiO₂ films by chemical bath deposition. The solar cells based on CdSe QD-sensitized TiO₂ films were evaluated by measuring the incident photon to electron conversion efficiency (IPCE) and the photovoltaic performance. The TiO₂ film with bicontinuous pore structure showed a higher IPCE value and superior photovoltaic performance. The solar cell based on CdS and CdSe QDs co-sensitized 1.6 μm thick TiO₂ films can reach a peak IPCE value of 21% and a power conversion efficiency of 0.358% under the simulated sunlight (AM 1.5, 100 mW cm⁻²).