Improved efficiency of dye-sensitized solar cells through fluorine-doped TiO2 blocking layer

We report on improvement in the performance of dye-sensitized solar cells (DSSCs) through a fluorine (F)-doped TiO2 dense layer for use as a blocking layer. The F-doped TiO2 layer was deposited on commercial F-doped SnO2 (FTO) substrate by the hydrolysis of a TiCl4 aqueous solution with NH4F. Their structural, morphological, and optical properties were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy examinations. The photocurrent density–voltage characteristics show that DSSCs fabricated with the F-doped TiO2 layer exhibits higher conversion efficiency (∼5.24%) than ones with the undoped TiO2 layer (∼4.76%), and the bare FTO substrate (∼3.88%). This improvement is attributed to the combined effects of reduced interfacial resistance and effective blocking behavior by the F-doped TiO2 dense layer.