Template free titiania photoanodes modified with carbon black or multi-wall carbon nanotubes: Thermal treatment at low and high temperature for the fabrication of quasi-solid state dye sensitized solar cells

摘要

A simple procedure was developed to prepare modified titiania (TiO_2) photoanodes for dye sensitized solar cells at low and high temperature in order to improve overall cell efficiency. Modification of TiO_2 films achieved by the incorporation of either carbon black powder (CBP) or multi-wall carbon nanotubes (MWCNTs). A small quantity of titanium alkoxide was added in a dispersion of titiania (TiO_2) powder consisting of nanoparticles at room temperature, which after alkoxide's hydrolysis helps to the connection between titiania (TiO_2) particles and to the formation of mechanically stable relatively thick films on conductive glass substrates. The absence of surfactant allowed us to prepare films at relatively low temperature (~ 100 ℃), while the effect of sintering at a higher temperature (500 ℃) was also studied. The structural properties of the films were examined with porosimetry method and microscopy analysis. Better electrical results were obtained for the MWCNT (0.1 wt%) modified TiO_2 films, with 3.14% and 4.68% conversion efficiencies under 1 sun illumination after treatment at 100 ℃ and 500 ℃, respectively. The enhancement in photocurrent for MWCNT-TiO_2 films compared to pure TiO_2 films is attributed to the improved interconnectivity between TiO_2 nanoparticles, which further improved the electron transport through the film. For carbon doped CBP-TiO_2 cells, lower efficiencies were observed compared to pure TiO_2.