Visible-light wavelength matched microsphere assembly of TiO2 superfine nanorods and the enhanced photovoltaic performance

• Microsphere assembly of TiO2 nanorods with a diameter of ∼5 nm was fabricated.
• TiO2 microspheres size is well matched with the visible light wavelength.
• TiO2 microsphere enhances the light-scattering ability.
• Rutile TiO2 microsphere shows an energy conversion efficiency of 6.59%.
• The highest PCE reported for intrinsic rutile TiO2 is obtained.

According to the Mie scattering theory, spheres with the size matched with light wavelength are most suitable for light scattering and enhance the light trapping ability. In this paper, a novel visible-light wavelength matched sphere assembly of TiO2 superfine nanorods was fabricated via a simple one-step hydrothermal method. The morphology and the structure were examined by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The visible subwavelength TiO2 microsphere resembling an immature chinese chestnut is composed of countless superfine TiO2 nanorods, the diameter of these building blocks of superfine TiO2 nanorods is ∼5 nm. The obtained TiO2 sphere has an average diameter of ca. 450 nm, which matches well with the visible light wavelength and cause the effective light-scattering effect. Furthermore, these TiO2 superfine nanorods formed V-shaped structure which is usually designed in traditional silicon solar cells. Study show the as-prepared rutile TiO2 spheres has a good light-trapping property and an excellent photovoltaic performance. Even though the dye absorption is two times lower than that of the widely used anatase TiO2 nanoparticles, the obtained rutile sample shows a satisfactory energy conversion efficiency of 6.59% and is the highest PCE reported for intrinsic rutile TiO2. The further optimized DSSC shows a photo to electron conversion efficiency of 8.3%.

A novel visible-light wavelength matched microspheres assembly of TiO2 superfine nanorods with a diameter of ∼5 nm was fabricated via a hydrothermal method. The as-prepared rutile TiO2 microspheres have a uniform diameter of ∼450 nm and show a good light-trapping performance. Dye-sensitized solar cell based on this sample shows a satisfactory energy conversion efficiency of 6.59% and is the highest PCE reported for intrinsic rutile TiO2. The further optimized DSSC shows a conversion efficiency of 8.3%, though the internal resistance is higher and the dye absorption is lower than that of widely used anatase TiO2 nanoparticles.Figure optionsDownload as PowerPoint slide