Fabrication of TiO2 microspheres with continuously distributed sizes from nanometer to Micronmeter: The increasing light scattering ability and the enhanced photovoltaic performance

• TiO 2 microsphere with continuously distributed sizes were synthetized. • The diameters matched with sunlight wavelength distribute from 300 nm to 3 μm. • The specific surface area of the prepared TiO 2 microsphere is 49 m 2 g −1 . • The optimzed device show 22.4% increase in PCE with 30.4% decrease of dye loading. It is well-known that the wavelength of sunlight is continuously distributed from nanometer to micronmeter. Spheric particles with the size matched with sunlight wavelength are most suitable for the light scattering and enhance the light trapping ability according to the Mie scattering theory. In this paper, a multi-sized TiO 2 microsphere (MTS) was synthesized via a facile solvothermal method. The obtained MTS samples were then investigated by field emission-scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), size distribution measurement, and N 2 adsorption–desorption measurement. FE-SEM images and size distribution curves indicate that the diameters of MTS samples range from 300 nm to 3 μm which is matched with sunlight wavelength. The possible formation mechanism of multi-sized TiO 2 microsphere was also proposed. Furthermore, the optoelectronic properties of such MTS samples were explored by manufacturing them as photoanodes in dye-sensitized solar cells (DSSCs). The UV–Vis spectrum shows that the MTS has a high capacity for light scattering, which is essential for DSSCs to perform well. Interestingly, even under the condition with 30.4% decrease of dye loading, the DSSC with MTS samples as the top scattering layer showed an energy conversion efficiency of 7.22%, showing 22.4% increase in conversion efficiency when compared with the DSSC without using the top scattering layer. The novel as-prepared MTS samples as photoanodes can effectively boost light scattering and enhance the performance of the device, thus opens a door for the further utilization of sunlight in Dye-sensitized solar cells.