The semiconductor oxide material titanium dioxide (TiO2) has a number of strategic uses, such as an antimicrobial, self-cleaning, photocatalyst, and dye-sensitized solar cell (DSSC). Despite the fact that his substance is naturally obtained from the ilmenite (FeTiO3) mineral, there have been few investigations in this field. This work produced heterogenous TiO2 nanocrystals from ilmenite extraction, which were then subjected to post-hydrothermal treatment at a range of temperatures of 80, 100, 120, and 150 °C. In the present study, it was examined how temperature change affected the optical characteristics, crystal structure, and prospective integration of TiO2 nanocrystals into DSSC. The obtained TiO2 nanocrystals were identified as anatase phase by the X-ray diffraction analysis. As a result of raising the post-hydrothermal temperature from 80 to 150 °C, the crystallite size of heterogenous TiO2 nanocrystals was successfully enhanced from 58.09 to 72.48 nm. The band gap energy (Eg) may be lowered from 2.81 to 2.65 eV by increasing the size of the crystallites. The greatest open circuit voltage (Voc) measured by the voltage test findings was 16.80 mV. According to the study's findings, heterogenous TiO2 nanocrystals synthesized from the ilmenite mineral might be used in dye-sensitized solar cell applications. © 2023