Atomic layer deposition of TiO 2 interfacial layer for enhancing performance of quantum dot and dye co-sensitized solar cells

Quantum dots (QDs) and dye co-sensitized solar cells have attracted substantial interest due to the enhanced light absorption for conversion efficiency improvement. To overcome the charge-collection issue and the QD degradation in the I − /I − 3 electrolyte, here we report our investigations on adding a nano-TiO2 interfacial layer between CdS QDs and N719 dyes for enhancing the performance of the co-sensitized solar cell. Atomic layer deposition is used to fabricate conformal and uniform TiO2 interfacial layers with a thickness of 1.5, 2.2 and 3.2nm. It has been found that the addition of a TiO2 interfacial layer can improve the device performance significantly (from 1.67% to 2.36%) through reducing the electron recombination and improving the QD stability in electrolyte, while there is an optimum thickness for the TiO2 interfacial layer. (Some figures may appear in colour only in the online journal)