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.