Optimization of the TiO2-surface modification temperature for performance enhancement of dye-sensitized solar cells.

A nanoporous TiO2 electrode was modified with magnesium salts (MSs), MgCO3 and Mg(CH3COO)2, by simple dip coating process at varied temperatures, and then applied to dye-sensitized solar cells (DSSCs). When the surface treatment was conducted at 40 °C, the DSSC with MS-modified TiO2 layer showed an increase in short circuit current (JSC) and open circuit voltage (VOC), resulting in a power conversion efficiency of 8.52%, compared to that (7.02%) of reference device with bare TiO2. The improved JSC value was attributed to the increased dye adsorption. Electrochemical impedance spectroscopy and dark current-voltage studies revealed that the VOC enhancement was caused by the suppression of charge recombination between injected electrons and I3(-) ions.