Synergistic assembly of nanoparticle aggregates and texture nanosheets into hierarchical TiO2 core–shell structures for enhanced light harvesting in dye-sensitized solar cells

Abstract

In this study, we report a facile one-step solvothermal approach for growing nanoparticle aggregates–texture nanosheets hierarchical TiO₂ core–shell structure (HTCSS) via the synergistic interaction of butylamine and ethanol. Under specific conditions, the products obtained in ethanol tended to aggregate into spherical structures, but in butylamine preferred to form nanosheet structures. Optimal cooperation between butylamine and ethanol leads to the formation of a core–shell structure with nanoparticle aggregates as the core and texture nanosheets as the shell. The HTCSSs cover a wide radius range from 150 to 800 nm, which is comparable to the wavelength of visible light. Therefore, they can be effectively used as light scattering materials to improve light harvesting in dye-sensitized solar cells (DSCs). Furthermore, the HTCSSs possess a very high surface area of 228.5 m² g⁻¹ and main pore size centered at 2.0 nm. DSCs using HTCSSs with bifunctional character of light scattering and high surface area properties showed an photoconversion efficiency of 8.90% under AM1.5 illumination, which was much higher than that derived from P25 nanoparticles of an optimized film thickness (6.09%).