Scientists design new solar cell to improve efficiency

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Physicists at Paderborn University have made a significant leap forward in the quest for more efficient solar cells, thanks to the power of complex computer simulations.

They’ve crafted a new design that incorporates a thin layer of an organic material called tetracene, which boosts the cell’s efficiency in converting sunlight into electricity.

This development, detailed in Physical Review Letters, could revolutionize how we harness solar energy.

The importance of solar energy can’t be overstated.

With the sun showering the Earth with over one trillion kilowatt hours of energy annually—over 5,000 times our global energy demand—solar power stands out as a vast, yet underutilized, source of clean and renewable energy.

Currently, the market is dominated by silicon solar cells, which, despite their prevalence, have efficiency limits. A significant portion of the energy from short-wave radiation, for instance, is lost as unwanted heat instead of being converted into electricity.

To tackle this issue, the team at Paderborn University, led by Prof Dr. Wolf Gero Schmidt, suggests adding an organic layer of tetracene to the silicon solar cells.

Tetracene absorbs short-wave light, transforming it into high-energy electronic excitations known as excitons.

These excitons then decay within the tetracene into two lower-energy excitations. If these can be transferred to the silicon cell efficiently, they could significantly boost the cell’s electricity production.

A major breakthrough came when the team discovered that introducing specific defects at the interface between the tetracene layer and the solar cell could dramatically speed up the transfer of excitations from tetracene to silicon.

These defects, typically seen as detrimental because they’re associated with energy loss, here play a crucial role. They form when hydrogen desorbs, creating electronic interface states that fluctuate in energy.

These fluctuations effectively “carry” the electronic excitations from the tetracene into the silicon, much like an elevator.

This counterintuitive finding—that defects could be beneficial for energy transfer in solar cells—marks a radical departure from conventional wisdom.

The Paderborn team’s computer simulations, run on the university’s high-performance computing center, offer precise insights into designing a new type of solar cell with significantly enhanced efficiency.

This research not only highlights the untapped potential of solar energy but also showcases the innovative approaches being developed to overcome the limitations of current technology.

By integrating materials like tetracene into solar cells, we’re moving closer to unlocking a cleaner, more sustainable energy future.

The research findings can be found in Physical Review Letters.

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