A cheap alternative to silicon solar cells can be found in dye-sensitised solar cells. This type of cell imitates the natural conversion of sunlight into energy by, for instance, plants and light-sensitive bacteria. Annemarie Huijser has succeeded in substantially improving a process in this type of solar cell, which is similar to Grtzel cells. Huijser will receive her PhD on this subject from TU Delft on Tuesday 25 March.
The use of solar cells is increasing very slowly. One of the reasons is that the most commonly used type, made from silicon, is quite expensive to manufacture. That is why there has been a great deal of research into alternative solar cells over the past few years.
In searching for solutions, scientists are inspired by nature. Plants are able to transport absorbed solar energy over long distances, typically about 15-20 nanometres, to a location in which it is converted into chemical energy. This is because the chlorophyll molecules in their leaves are arranged in the best possible sequence. During her PhD, Annemarie Huijser attempted a partial recreation in solar cells of this process as found in plants.
She focused on what are known as dye-sensitised solar cells. These comprise a semiconductor, such as titanium dioxide, covered with a layer of dye. The dye absorbs energy from sunlight, which creates what are known as excitons. These energy parcels then need to move towards to the semiconductor. Once there, they generate electric power.
Huijser: You can compare dye molecules to Lego bricks. I vary the way the bricks are stacked and observe how this influences the exciton transport through the solar cells. Excitons need to move as freely as possible through the solar cells in order to generate electricity efficiently.
By studying the best sequence of dye molecules, Huijser succeeded in increasing the average distance which the excitons move in the solar cell by twenty times up to a
|Contact: Ineke Boneschansker|
Delft University of Technology