In-depth investigation of microstructure and optical properties of tri-phase TiO2 nanoparticles at varied calcination temperatures for dye sensitized solar cells (DSSCs) applications

Abstract

Tri-phase TiO2 nanoparticles are synthesized by facile hydrothermal method and calcinated within a temperature range of 450 °C–1050 °C. These nanoparticles are utilized as photoanode material in dye-sensitized solar cell (DSSC) applications. The device fabricated by utilizing TiO2 NPs calcinated at 600 °C reveals a maximum power conversion efficiency (η) of 3.79 %, with a current density (Jsc) of 7.83 mA cm−2 under one sun illumination among all tested devices. This exceptional achievement is related to the synergistic effect of 49 wt % anatase, 39 wt % rutile and 12 wt % brookite content in triphasic TiO2 NPs. The anatase emerges as the most active phase providing a sufficient surface area for dye adsorption, and in parallel rutile phase enhances the scattering of light that potentially boosts mobility and injection of photogenerated electrons (e-s) from the LUMO level (ELUMO = −3.8 eV) of N719 dye to the conduction band (ECB = −4.28 eV). Simultaneously, the presence of the brookite phase reduces the charge-carriers ((e−), (h+)) recombination rate at the TiO2 photoelectrode/electrolyte interfaces because brookite has an inherent resistance to back electron transfer. The effective light-harvesting capabilities of triphasic TiO2 NPs position them as promising contenders for dye-sensitized solar cells (DSSCs).