Physicists develop new solar cell design for better efficiency

Physicists at the University of Paderborn have used complex computer simulations to develop a new design for solar cells that is significantly more efficient than previously available. A thin layer of organic material, called tetracene, is responsible for the increased efficiency. Now the results are out. published I Physical examination letters.

“The annual energy of solar radiation on Earth is more than one trillion. Kilowatt hours And thus more than 5,000 times the global energy demand. Photovoltaics, i.e. the generation of electricity from sunlight, therefore offers a huge and still largely untapped potential for providing clean electricity. Renewable energy. Silicon solar cells used for this purpose currently dominate the market, but their efficiency is limited,” explains Prof. Dr. Wolf Gero Schmidt, physicist and dean of the Faculty of Natural Sciences at the University of Paderborn. His One reason is that it yields some energy.Shortwave radiation is not converted into electricity, but into unwanted heat.

Schmidt explains, “To increase efficiency, Silicon The solar cell can be provided with an organic layer, for example made from the semiconductor tetracene. Shortwave light is absorbed in this layer and converted to high energy. Electronic stimulation, the so-called excitons. These excitons decay into two lower energy excitations in tetracene. If these excitations can be successfully transferred to a silicon solar cell, they can be efficiently converted to electricity and increase the overall usable energy production.”

Decisive advances for high-speed energy transfer

Tetracene-induced transitions in silicon are being investigated by Schmidt’s team using complex computer simulations at the university’s high-performance computing center, the Paderborn Center for Parallel Computing (PC2). A decisive breakthrough has now been achieved: in a joint study with Dr. Marvin Krenz and Prof. Dr. Yves Gerstmann from the University of Paderborn, the scientists have shown that the unsaturated chemical bond at the interface between tetracenes Defects. Film and solar cells dramatically accelerate exciton transfer.

Schmidt notes, “Such defects arise during hydrogen abstraction and cause electronic interface states with fluctuating energy. These fluctuations transfer electronic excitation from tetracene to silicon as a lift.” “

Such “defects” in solar cells are actually associated with energy losses. This makes the findings of the trio of physicists even more surprising.

“In the case of the silicon tetracene interface, defects are essential for fast energy transfer. The results of our computer simulations are truly surprising. They also provide valid indications for the design of new types of solar cells with significantly increased efficiency. provide,” Schmidt says.