Red algae as a source of pigments in DSSC type photovoltaic cells (phase II)

Dr Mª Fernanda Cerdá, Facultad de Ciencias

Within the renewable energies, solar is an extremely attractive alternative. The Sun is an inexhaustible and powerful source of energy, so its use can provide a solution to the current energy demand. And more importantly: solar energy comes everywhere.

Solar panels are extremely well known. Most of the solar panels produced today are made from Silicon, the second most abundant element on Earth. However, these panels have some disadvantages: for better performance the silicon must be purified (which increases its cost) and running on a small part of the spectrum of sunlight (within the range of UV light).

But there is an alternative little known in our country, panels based on natural dyes, like pigments that can be obtained from plants and fruits. They are known as cells DSSC or Grätzel, in honor of its creator. These panels use a much broader spectrum of light energy range (for the service of colors, operating within the visible range) and have a lower cost than silicon panels. They have the added advantage that they can be placed inside a building as if they were colored stained glass. If you think of an area with a climate as extreme as Antarctica, the use of silicon panels placed outdoors is an discarded option. In contrast, the use of DSSC cells can be raised, since on the one hand it needs less light to operate (because they take better advantage of the power that arrives) and on the other hand can be placed indoors.

Of the sources that are presented in Antarctica to extract pigments, red algae are the most abundant and the protein responsible for its red color has the characteristics suitable to be used in these cells. The red pigment is extracted from the algae and adhered on a conductive glass containing a material containing titanium, such as white paints.

The pigment has to capture sunlight and transform it into electrons, yielding to titanium. This transforms this sector of the cell into the negative pole of the cell. The positive pole has carbon, and as the false electrons have greed for them. In conclusion, a panel consists of several cells or cells, which have one positive pole and one negative pole.

The cycle can be described as follows:

1- the red pigment receives sunlight and releases electrons

2- these electrons go to titanium (the pole becomes negative because of the excess electrons)

3- these electrons are directed to the carbon (positive pole because they are missing)

4- this way electric current is produced.

We have collected algae of different type and extracted the red pigment, which meets the characteristics suitable to be used. And we have built cells with these pigments, which work, but we still have a lot to improve. Our challenge is to improve the performance of these batteries.