Hydrothermal synthesis of well-aligned hierarchical TiO2 tubular macrochannel arrays with large surface area for high performance dye-sensitized solar cells

Well-aligned hierarchical TiO2 tubular macrochannel arrays (HTTMAs) with high surface area have been synthesized via a facile one-step ammonia hydrothermal synthesis process without using any structure-directing templates. The typical samples are made of an assembly of macrochannels with uniform openings centered at 2.2 μm and a channel density of 1.7 × 107 cm−2. The interconnected macro-mesoporous samples possess a high surface area of 229.6 m2 g−1 and main pore size centered at 4.1 nm. Powder X-ray diffraction and transmission electron microscopy demonstrated that the samples had a mixture of rutile and anatase phases. The light scattering properties of samples were studied by UV–Vis spectrometer in the 350–800 nm wavelength range. Dye-sensitized solar cells made of HTTMAs showed an energy conversion efficiency of 8.10% under AM1.5 illumination, which was much higher compared to that (6.24%) of cells consisting of P25 nanoparticles with the same film thickness.