Dyesensitized

Dyesensitized is an adjective used in materials science to describe a system whose optical or electronic properties are conferred or enhanced by adsorbed dye molecules. The concept is most widely associated with dye-sensitized solar cells (DSSCs), where a dye molecule acts as a photosensitizer on a wide-bandgap semiconductor such as titanium dioxide. In these cells, the dye absorbs visible light, becomes excited, and injects an electron into the semiconductor's conduction band. The oxidized dye is then reduced back by a redox mediator in the electrolyte, completing the cycle.

Dyesensitized systems extend to other photoactive phenomena, including dye-sensitized photocatalysis, where excited-state dye molecules enable charge separation on surfaces to drive chemical reactions such as pollutant degradation or water splitting. The performance of a dye-sensitized device depends on the dye's absorption properties, energy level alignment, anchoring groups that bind to the semiconductor, and the stability of the dye under operating conditions.

Historically, the concept was demonstrated in the 1990s by researchers including Michael Grätzel, leading to rapid growth in research on inexpensive, low-temperature processing solar cells. Contemporary research focuses on developing robust, broad-spectrum dyes and solid-state electrolytes or hole transport materials to improve stability and efficiency. The term can also apply to other dye-adsorbed, photosensitive materials used in sensors or photodetection, though dye-sensitized solar cells remain the most prominent example.