LAUSR

Natural bacteriochlorophyll (BChl) a from purple bacteria possesses the near-infrared absorption, high extinction coefficient and excellent photoelectric properties. It is a promising natural pigment sensitizer candidate for fabricating near-infrared responsive dye-sensitized solar cell (DSSC). However, its low adsorption capacity on TiO2 film limited its photoelectric performance. To enhance adsorption capacity of BChl a on the electrode, in this study, the TiCl4 and acetic acid treatment were used to modify the TiO2 film (named as T-TiO2 film and A-TiO2 film, respectively). The optimal adsorption parameters were examined by adsorption kinetic and adsorption isotherms of BChl a on the different types of TiO2 films. The effects of TiO2 film thickness and pigment concentrations on adsorption capacity and photoelectric properties of BChl a were systematically investigated. The results showed that T-TiO2 film achieved the maximum adsorption capacity and adsorption rate for BChl a, the adsorption capacity of BChl a was increased gradually with increasing TiO2 film thickness, but the best photoelectric performance was obtained at the moderate film thickness of 10 μm and 480 μg·ml -1 of BChl a. The maximum short-circuits current and photoelectric conversion efficiency of DSSC obtained were 3.51 mA·cm -2 and 1.67% at 100 mW·cm -2 , which were eight times and fifteen times higher than those of untreated TiO2 films with thickness of 6 μm, respectively.