Normally, it has been widely acceptable that dye sensitized solar cell (DSSC) plays important roles compared to the conventional solar
cells such as monocrystalline, polycrystalline, and even amorphous silicon in accordance with its low manufacturing and fabrication
cost. However, the DSSC consists of many interfaces between anode and cathode such as semiconductor to dye and dye to electrolyte
and electrolyte to platinum catalyst at the cathode. Therefore, the effect of charge recombination at dye-electrolyte interface is a major
role to cell efficiency. One of major implementations to alleviate the recombination effect could be efficiently solved by adding
hydrophobic co-adsorbent to dye solution. The co-absorbent molecule will be anchored to titanium dioxide semiconductor like dye
and can be the barrier to protect the interface of the triiodide, dye and mesoporous titanium dioxide (TiO2).
In our works, we investigate on various hydrophobic co-adsorbent such as 1-adamantane acetic acid, cholic acid and
chenodeoxy cholic acid. The amounts of the co-absorbent were varied as well as the amount of dye N719. It was found that the cholic
and chenodeoxy cholic acid increase photovoltage and photocurrent, especially when the concentration was increased. This may be
due to shift of conduction band (CB) to negative direction by the co-absorbent but 1-adamantane-acetic acid could not resist charge
recombination. In addition multilayer of titanium dioxide was also studied on the effect of conversion efficiency. The maximum 4
layers of TiO2 provided the best cell performance of 8.3 efficiency with the presence of cholic acid.