Influence of nature of surface dipoles on observed photovoltage in dye-sensitized solar cells as probed by surface potential measurement

A contact free method of surface potential measurement using scanning Kelvin-probe microscopy (SKPM) was conducted to probe the nature of nanocrystalline TiO2/dye interface. In combination with electrical measurements an effort has been made to establish a correlation between the nature of sensitizing dye and observed surface potential with open circuit voltage (Voc) after dye-sensitized solar cell (DSSC) fabrication. Effect of chenodeoxycholic acid (DCA) as co-adsorbent with dyes upon the enhancement of DSSC efficiency has been probed by SKPM, which revealed a positive shift of surface potential upon treatment of thin films of TiO2 with DCA. The enhancement of DSSC performance upon DCA introduction has been explained by upward shift of TiO2 conduction band edge leading to enhanced Voc along with the prevention of π-stacked aggregation resulting in enhanced short-circuit current density.