Performances Enhancement of Natural DSSC by Ga-Doped ZnO Layer Used in the FTO/TiO2/ZnG Photoanode

Abstract

Zinc oxide films doped with gallium (ZnG) were used as photoanodes in the dye sensitized solar cells (DSSCs). To enhance the electrical parameters of DSSC and decrease the recombination rate, a titanium dioxide (TiO2) thin layer is inserted between a ZnG photoanode and substrate. Optical, structural, and morphological properties of films deposited on indium tin oxide coated on polyethylene naphthalate (ITO/PEN) and fluorine-doped tin oxide (FTO) substrates are studied. The realized films have a polycrystalline wurtzite hexagonal structure with the preferred orientation (002). By addition of gallium (Ga) to the ZnO solution, an improvement of the crystallinity is observed by increasing the grain size from 16.68 to 22 nm for the FTO/films and from 7 to 16.76 nm for ITO-PEN/films. The realized DSSCs show an increase of efficiency from 0.44% to 0.57% for DSSCs based on FTO and from 0.13% to 0.15% for ones based on ITO/PEN. The dyeing of the photoanodes by the natural mallow improves light absorption through the appearance of the absorbance regions in the range 665–680 nm. The doping of ZnO with Ga improves the open-circuit voltage of realized DSSC from 0.57 to 0.59 V for the DSSCs based on FTO and from 0.55 to 0.58 V for ones made on ITO/PEN.