The use of sputter deposited TiN thin film as a surface conducting layer on the counter electrode of flexible plastic dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) have attracted widespread interests due to their low cost and facile fabrication. A typical DSC is composed of dye-sensitized mesoporous photoelectrode on a transparent conducting oxide (TCO) current collector, electrolyte containing iodide/triiodide redox couples, and a Pt coated TCO counter electrode. Due to the rareness and the high cost of ITO, other materials are being considered as replacements. For DSCs, light transmission is through the photoelectrode site. Therefore, the transmittance of the counter electrode is not as critical. In this study, Pt/TiN thin film has been used as a counter electrode. The TiN thin film was obtained through a reactive dc sputter deposition technique near room temperature. Flexible PEN foils were used as the substrates. Pt was deposited subsequently after TiN thin film deposition. The obtained TiN thin film was examined and the performance of the obtained flexible plastic DCSs is then evaluated.

► Sputtering deposited Pt/TiN thin film on PEN substrate has been first used as a counter electrode.
► The sheet resistance of obtained TiN is similar to that of ITO on PEN, i.e., approximately 15 Ω/sq.
► Using TiN to replace ITO enhances cell efficiency by as much as 60%.
► The increased light harvesting due to the higher reflectivity of the TiN layer