Researchers of the EPFL and Stanford University have developed a new generation of dye-sensitised solar cells. Thanks to the addition of a second dye, they react to a wider light spectrum than do conventional dye-sensitised solar cells and are therefore more efficient.
Owing to the addition of a second dye, the new dye-sensitised solar cells – also called Grätzel cells after their inventor, Prof. Michael Grätzel – react to a wider light spectrum than before. The technology has been developed by the EPFL and Stanford University (USA).
Reacting to a wider range of colours
Conventional dye-sensitised solar cells only react to the red part of the spectrum. With the addition of new dyes, namely the perylenes, cell sensitivity has been extended to the green and blue ranges of visible light, which has enhanced their efficiency.
Perylenes do not immediately produce electric charges. They react to the incidence of light and transmit this energy to the phthalocyanines, which then generate the charges. Previously, the dyes in photovoltaic cells had the task of generating electric charges directly. The new, indirect energy transmission has been inspired by nature. In plant photosynthesis, certain chlorophyll molecules emit signals which other chlorophyll molecules receive before they set in motion a process for the generation of electric charges. This type of energy transfer is known as dipolar interaction.
Energy transfer higher by one quarter
At present, the new dye-sensitised solar cells are being tested at the EPFL. The results are promising. The energy transfer capacity has been boosted by 26 per cent in comparison with photovoltaic cell systems based on phthalocyanine alone. The model has further potential since, for example, a system involving three or even four dyes is also conceivable.
