Astaxanthin from Haematococcus pluvialis as a natural photosensitizer for dye-sensitized solar cell

An extract of photosynthetic pigments from Haematococcus pluvialis was evaluated as sensitizer for solar cells. Nutrient-stressed H. pluvialis was cultured in a modified WC medium and harvested in the mature aplanospore stage. A crude extract was obtained and purified by column chromatography, rendering a primary purified extract (PPE). A comparison between PPE and a pure astaxanthin standard (AS), applied as sensitizers to TiO2 film photoelectrodes, was carried out. The dye-sensitized solar cell (DSSC) was assembled under a sandwich scheme, where the photoelectrode faced the platinum counter electrode and an iodide electrolyte solution was between them. Photoelectric conversion efficiency was measured using a solar simulator under a single sunlight intensity (100 mW cm(-2)). The photoelectrode sensitized with PPE showed higher efficiency (0.1%), fill factor (0.72), open circuit voltage (0.449 V) and short circuit current density (0.313 mA/cm(2)) than those with AS. The increased efficiency obtained using a PPE was attributed to a broader absorption range in the visible region, as well as the thorough internalization and distribution of the molecules in the mesoporous semiconductor (TiO2). Results indicated that the use of semi-purified extracts allows time and costs reduction of the production process for dye-sensitized solar cells applications.