Efficiency improvement and full characterization of DSSCs with MWCNT/anatase Schottky junctions

During the past 20 years, dye-sensitized solar cells (DSSCs) emerged and developed as a promising and low cost alternative to traditional photovoltaics. One of the main obstacles to mass-scale introduction of this technology is represented by their relatively modest conversion efficiency. In this paper, the authors propose and verify the possibility of improving the performance of the devices by taking advantage of the spontaneous formation of Schottky-type rectifying junctions between multi-walled carbon nanotubes and anatase nanoparticles in the preparation of DSSC photoanodes. These junctions improve the charge transport toward the anode with respect to the charge recombination phenomena. A model anatase-graphite Schottky diode was also prepared and characterized in order to verify on macroscopic scale the formation of a Schottky-type junction between the two materials. At 0.1 wt% of MWCNTs a 55% increase of efficiency with respect to DSSCs without MWCNTs has been obtained. The role of the optimum concentration of MWCNTs in the photoanode is discussed on the light of the DSSC electrical parameters taken up from various techniques.