(229e) Reducing Electron Recombination in Dye Sensitized Solar Cells: A Comparative Study

Establishing a compact barrier layer on the interfaces of photoanode is an effective approach to reduce the electron recombination in dye sensitized solar cells (DSSCs). However, electron recombination on transparent conductive oxide (TCO) and on TiO₂ has not been compared to identify the dominant recombination process. In this work, by depositing HfO₂ as barrier layers via atomic layer deposition (ALD) on tin-doped indium oxide (ITO) and TiO₂, the recombination processes on the two interfaces are compared. 2 cycles of ALD deposition on ITO and TiO₂ lead to their respective highest efficiency of 7.10% and 7.25%, corresponding to an enhancement of 10% and 10.4%, respectively. With more than 2 ALD cycles, the barrier layers showed blocking effect regardless of the location of deposition, resulting in decrease of efficiencies. Fill factor (FF) was seen to change with shunt resistance (R_sh) and series resistance (R_se), which in turn depend on the location of barrier layers. Depositing barrier layer on ITO did not impact R_sh and R_se, leaving FF unchanged. Depositing barrier layer on TiO₂ leads to decrease of R_sh and increase of R_se, which ultimately reduced FF.