Atomic layer deposition of TiO2 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-/I3- 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 3.2 nm. 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.