The sensitizer, or dye, is crucial as it absorbs sunlight and converts it to electrical energy. The dye's efficiency as a catalyst is determined by its ability to absorb a broad spectrum of light and its alignment with the conduction band of TiO2. Ruthenium-based dyes are commonly used due to their robust performance, but research is ongoing to develop organic dyes and perovskite materials that could offer higher efficiency and better environmental compatibility.
