Transparent semiconductive TiO2 films co-doped with Ru and Ta (Nb), and Co and Nb (Sb) were prepared on SiO2 glass substrates by the sol-gel method using Ti(OC3H7 i)4 solutions. The solution preparation condition, solution composition, dopant content and heat-treatment temperature all severely affected the electrical resistivity of the resultant films. TiO2 films co-doped with Ru and Ta (Nb) showed n-type conductivity, while those co-doped with Co and Nb (Sb) showed p-type conductivity. It seems that the obtained films can be utilized for assembling all-solid-state TiO2-based pn type solar cell
