A PhD student at TU Delft, The Netherlands, has succeeded in substantially improving the efficiency with which dye-sensitised solar cells convert sunlight into energy.
The most commonly used type of solar cell, made from silicon, is quite expensive to manufacture, spurring a great deal of research into alternative solar cells over the past few years.
In searching for solutions, scientists have turned to 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.
Graduate student Annemarie Huijser attempted a partial recreation in solar cells of this process as found in plants.
Huijser, who received her PhD on the subject at the end of March, uses a Lego analogy to explain what she did. 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.
“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 distance of approximately 20 nanometres, comparable to systems found in nature. This substantially increases the efficiency of the cells.
In order to make this new type of solar cell commercially viable, Huijser estimates that the mobility of the excitons needs to increase further by a factor of three. She believes that this is certainly possible. “Once that has been achieved, there is nothing to stop this type of solar cell being developed further.”
The most commonly used type of solar cell, made from silicon, is quite expensive to manufacture, spurring a great deal of research into alternative solar cells over the past few years.
In searching for solutions, scientists have turned to 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.
Graduate student Annemarie Huijser attempted a partial recreation in solar cells of this process as found in plants.
Huijser, who received her PhD on the subject at the end of March, uses a Lego analogy to explain what she did. 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.
“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 distance of approximately 20 nanometres, comparable to systems found in nature. This substantially increases the efficiency of the cells.
In order to make this new type of solar cell commercially viable, Huijser estimates that the mobility of the excitons needs to increase further by a factor of three. She believes that this is certainly possible. “Once that has been achieved, there is nothing to stop this type of solar cell being developed further.”
Receive the Funding Newswire [full access requires a subscription] each Tuesday, our Policy Bulletin each Thursday, and news about bridging Europe’s east-west innovation gap twice a month in The Widening. 
A unique international forum for public research organisations and companies to connect their external engagement with strategic interests around their R&D system.
