A team of FAU researchers led by Nicola Gasparini, a doctoral candidate at FAU’s Chair of Materials for Electronics and Energy Technology, has made an important step towards creating more efficient solar cells. The researchers were able to increase the fill factor – which describes the efficiency of a solar cell – to 77 percent, thereby increasing the amount of light that the cell makes use of. The researchers’ findings have recently been published in the journal Nature Energy*.
‘As the efficiency of a solar cell is proportional to its fill factor, our goal was to increase the fill factor to make them more efficient than they are currently,’ Nicola Gasparini explains. The overall aim is to develop organic solar cells as a replacement for standard silicon cells and in doing so make photovoltaics a competitive alternative to fossil fuels.
However, so far little research has been carried out on the fill factor, which describes the efficiency of a solar cell. The closer the fill factor is to 100 percent, the higher the cell’s efficiency. ‘We have reached 77 percent. That’s a very high value. Before now similar efficiencies had only been achieved with silicon cells.’
Like silicon cells, solar cells convert light into electricity. However, in contrast to the silicon cells that can often be found in photovoltaic systems on the roofs of buildings, organic solar cells are made of special semiconductor-based polymers called fullerenes – minute carbon molecules that look like footballs.
In order to increase light absorption in organic solar cells, Nicola Gasparini and his colleagues at the Chair of Materials for Electronics and Energy Technology, headed by Prof. Dr. Christoph Brabec, developed a new combination of several polymers which absorbs sun light completely. Thanks to the combination of materials the researchers succeeded for the first time not only in achieving full absorption but also in reducing losses.
Highly efficient organic cells based on this technology could open up new markets, particularly in the automotive and aviation industries in which increasing efficiency and reducing weight are very important.