Various weight percentages of titanium nitride (TiN) and thermally-treated titanium nitride (tt-TiN) are incorporated into the binder-free TiO2 films, prepared at low temperature (LT, 120 degrees C), and the corresponding dye-sensitized solar cells (DSSCs) are made. Effects of their incorporation on the photovoltaics of the DSSCs are studied. With the incorporation of 0.125 wt% of TiN in a TiO2 film of only 5.5 mu m-thickness, the corresponding solar-to-electricity conversion efficiency (eta) has reached to 3.40% from 2.38% of a cell with a bare TiO2 film of same thickness; this increase in efficiency is attributed to the higher electron conductivity and longer electron life time in the TiO2 film with TiN. Incorporation of 1.0wt% of tt-TiN into the TiO2 film has further improved the conversion efficiency to 3.77%; this further enhancement in the efficiency is attributed to the partial conversion of TiN into TiO2 due to the thermal treatment (450 degrees C). X-ray diffraction (XRD) and a scanning electron microscopy (SEM) are used to study the partial conversion of TiN into TiO2. Other explanations are supported by the data of UV-absorption spectra, elecrtrochemical impedence spectroscopy (EIS), and laser-induced photo-voltage transients. (C) 2010 Elsevier B.V. All rights reserved.