Development of dye-sensitized solar cells with sputtered N-Doped Ti[O.sub.2] thin films: from modeling the growth mechanism of the films to fabrication of the solar cells

In this paper, nitrogen-doped Ti[O.sub.2] thin films were deposited by DC reactive sputtering at different doping levels for the development of dye-sensitized solar cells. The mechanism of film growth during the sputtering process and the effect of the nitrogen doping on the structural, optical, morphological, chemical, and electronic properties of the Ti[O.sub.2] were investigated by numerical modeling and experimental methods. The influence of the nitrogen doping on the working principle of the prototypes was investigated by current-voltage relations measured under illuminated and dark conditions. The results indicate that, during the film deposition, the control of the oxidation processes of the nitride layers plays a fundamental role for an effective incorporation of substitutional nitrogen in the film structure and cells built with nitrogen-doped Ti[O.sub.2] have higher short-circuit photocurrent in relation to that obtained with conventional DSSCs. On the other hand, DSSCs built with nondoped Ti[O.sub.2] have higher open-circuit voltage. These experimental observations indicate that the incorporation of nitrogen in the Ti[O.sub.2] lattice increases simultaneously the processes of generation and destruction of electric current.