Transparent quasi-solid state dye-sensitized solar cells sensitized with naturally derived pigment extracted from red seaweed

• Red seaweed pigments as sensitizers for TiO2 nanocomposite films.
• Transparent dye sensitized solar cells with natural sensitizer.
• Quasi-solid state electrolyte for natural pigments sensitized DSSCs.

Red seaweeds collected at Kefallinia Greek Island are examined for the first time as possible sensitizers in third generation photovoltaic cells. In particular, red seaweeds were collected and different solvents were used to extract their pigment through a simple procedure, in order to be used as a natural sensitizer for dye-sensitized solar cells. The dye solution with enhanced absorption in the visible spectrum was submitted to further absorption tests, where different pH and dye solution's temperature were tested to determine whether it affects the amount of the adsorbed dye on nanocrystalline TiO2 films. Solutions made with natural dye extracted from red algae in different solvents were used for the sensitization of TiO2 photoanodes and fabrication of quasi-solid state dye-sensitized solar cells some of which exhibited very satisfactory results compared with the published values so far of other seaweed dyes. The solar cells were examined in terms of J–V characteristic curves under simulated solar illumination and the best performing ones were also tested under dark conditions, while electrochemical impedance spectroscopy was used to evaluate electrodes and electrolyte interfaces. The optimal results were obtained for an acidic dye solution (pH = 3) and for pigment's solution temperature of 35 °C where cells showed a short circuit current density of 1.26 mA/cm2 and an open-circuit voltage of 0.66 V.

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