The construction of dye-sensitized TiO2 solar cells is studied using a ruthenium complex, cis-di(thiocyanato)-N,N’-bis(2,2’-bipyridyl-4,4’-dicarboxylic acid)-ruthenium (II), as a photosensitizing molecule (dye) on TiO2 nanocrystallite films to determine the interfacial binding effect on photoenergy conversion efficiency. Photoconversion efficiency is improved by electrochemical treatment of TiO, films, or reflux treatment for effective anchoring of the photosensitizing molecules on TiO2 nanocrystallite films. Characteristics of interfacial binding between dye molecules and the TiO2 surface is determined and compared using IR and UV-visible spectra The ester-like linkage and the chelating carboxylato linkage are formed between carboxylic acid groups of ligands in dye molecules and TiO2 nanocrystallites. The ester-like linkage is observed as major on the film which shows relatively high photoenergy conversion efficiency. The improvement of cell properties such as open circuit cell voltage (V-oc) can be explained by the decrease in charge on bipyridine ligands of the dye molecule owing to the formation of the covalent-like linkage. The importance of binding states between photosensitizing molecules and TiO2 is discussed with a view to achieving high efficiency in dye-sensitized solar cell.