A novel photoanode architecture of dye-sensitized solar cells based on TiO2 hollow sphere/nanorod array double-layer film

A novel TiO2 double-layer (DL) film consisting of TiO2 hollow spheres (HSs) as overlayer and single-crystalline TiO2 nanorod arrays (RAs) as underlayer was designed as the photoanode of dye-sensitized solar cells (DSSCs). This new-typed TiO2 HS/RA DL film could significantly improve the efficiency of DSSCs owing to its synergic effects, i.e. the relatively large specific surface area of TiO2 HSs for effective dye adsorption, enhanced light harvesting capability originated from TiO2 RA film, and rapid interfacial electron transport in one-dimensional TiO2 nanorod arrays. The overall energy-conversion efficiency of 4.57% was achieved by the formation of TiO2 DL film, which is 16% higher than that formed by TiO2 HS film and far larger than that formed by TiO2 RA film (η = 0.99%). The light absorption and interfacial electron transport, which play important roles in the efficiency of DSSCs, were investigated by UV–vis absorption spectra and electrochemical impedance spectra.

The novel photoanode based on TiO2 hollow sphere/nanorod double-layer film has the highest η, which was due to its relatively large surface area, enhanced light-harvesting capability, small dark current, low transport resistance and long electron lifetime.Figure optionsDownload high-quality image (125 K)Download as PowerPoint slideHighlights
► Double-layer film photoanode was fabricated based on TiO2 nanorod arrays and hollow spheres.
► TiO2 hollow sphere overlayer had large surface area for effective adsorption of dye molecules.
► TiO2 nanorod array underlayer could improve electron transport rate and light harvesting efficiency.
► DSSCs based on TiO2 double-layer film had the maximum conversion efficiency.
► Our work opened up a new avenue for the development of DSSCs with high efficiency.