Scientists develop transparent nano-layers to make it possible for silicon photovoltaic cells to have an efficiency of more than 26%.

Nowadays, there is no cheaper way to generate electricity than using the sun. As long as power plants are built in sunny places, the price of solar power supply per kilowatt hour will be less than two cents. Crystalline silicon-based solar cells on the market make it possible, with a peak efficiency of 23%.

As a result, their share of the global market is about 95 per cent. If the efficiency exceeds 26%, the cost of power generation may fall further. An international team of photovoltaic researchers led by (Forschungszentrum J ü lich of the Uhrlich Research Center plans to achieve this through a transparent nanostructured material and complex design for the front end of solar cells, and published the results in the prestigious scientific journal Natural Energy.

Silicon solar cells have been steadily improved in the past few decades and have reached a high level of development. However, after absorbing sunlight and photovoltaic power generation, the recombination interference effect of charge carriers will still occur. In this process, the negative charge and positive charge carriers that have been generated combine and cancel each other out before they can be used in the production of solar power. This effect can be offset by special materials with special properties (passivation).

"our nanostructured layer happens to provide this ideal passivation," said Malte K ö hler, lead author of the study. "in addition, the ultra-thin layer is transparent, so the incident rate of light is hardly reduced and shows high electrical conductivity."

Dr. Kaining Ding, head of the J ü lich working group, said, "so far, there is no other way to combine these three characteristics-passivation, transparency and conductivity-like our new design."

Although the first prototype of J ü lich TPC solar cells achieved 23.99 per cent efficiency in the laboratory, it was still slightly lower than the best crystalline silicon cell ever made in the laboratory, the researchers said. However, simulations carried out at the same time show that it is possible to use TPC technology to achieve an efficiency of more than 26%.

"in addition, we only use manufacturing processes that can be relatively quickly integrated into a series of production," Ding stressed the advantages over other research methods. With this strategy, J ü lich scientists paved the way for their large-scale development from laboratory to industrial solar cell production without much effort.

Specifically, the production of TPC solar cell layer requires several technological steps. On a thin layer of silicon dioxide, the researchers deposited a layer of double-layer, tiny pyramid-shaped nanocrystals of silicon carbide, which were applied at two different temperatures. Finally, there is a transparent indium tin oxide layer. The researchers used wet chemical process, chemical vapor deposition ((CVD)) and sputtering process.

In further research, the team plans to further optimize the power efficiency of its TPC solar cells. "We want solar cell manufacturers to show great interest in our technology," Ding said.