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A simple technique was developed to fabricate a large-area TiO2 electrode layer using electrospun nanorods for dye-sensitized solar cells (DSSCs). Using this technique, we assembled DSSCs of area ∼1 cm2 consisting of a thin TiO2 nanoparticle layer and a thick TiO2 nanorod layer as electrode. The TiO2 nanorods were obtained by mechanically grinding electrospun TiO2 nanofibers. A titania sol was first spin-coated on a conductive glass plate and a TiO2 nanorod layer was next spray dried on it to fabricate TiO2 nanoparticle/nanorod layers. These layers were subsequently sintered. The best-performing DSSC evaluated under AM1.5G (1 sun) condition gave current density ∼13.6 mA cm−2, open circuit voltage ∼0.8 V, fill factor ∼51% and energy conversion efficiency ∼5.8%.

The anatase TiO 2 nanofibers of average diameters 60, 100, and 150 nm were fabricated by controlled electrospinning of a polymeric solution and subsequent sintering of the as-spun fibers. The sintered fibers were polycrystalline and composed of densely packed TiO 2 grains of size ∼12 nm. The rutile phase nucleated at the particle interface of the dense anatase TiO 2 nanofibers at a temperature of <570 °C because of the increased surface stress observed in these nanofibers. X-ray and electron diffraction measurements and analysis of the sintered fibers showed that the lattice strain increased with a decrease in the fiber diameter. The diameter-dependent lattice strain is attributed to the increased surface energy in fibers of lower diameter. The strain most likely originates from interplay of the surface charge and grain boundary effects. The absorption spectra of the fibers showed a red shift with an increase in the fiber diameter, which is attributed to an increase in the surface stress with a decrease in the fiber diameter.

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