Fraunhofer researchers manage to convert a third of sunlight with silicon-based photovoltaics.

New record in a photovoltaic register, in the center of ISE solar research from the Fraunhofer Institute, in collaboration with the EV group company, have succeeded in developing silicon-based multi-junction solar cells capable of converting a third of sunlight into electricity.

Institute Director Andreas Bett acknowledges that “Photovoltaic energy is a key pillar of energy transformation”, also over time “Costs have fallen so much that photovoltaics has become an economically viable competitor for conventional energy sources”

Although the development of this type of technology is not yet complete, for Bett “The new result shows how material consumption can be reduced through higher efficiency, so that not only costs can be further optimized, but also its manufacture can be done in a resource-friendly way.” and thus contribute to the balance in the environment.

Presence of silicon cells.

The company recognizes that silicon solar cells now dominate the photovoltaic market with a 90% share. New developments, technological research and the industry that manages them are bringing positions closer to improving the efficiency of semiconductor silicon, while opening up new avenues for the development of new generations of more efficient solar cells.

Fraunhofer researchers increased the efficiency of electrical conversion using silicon by relying on a multi-assembly solar cell system with extremely thin 0.002 millimeter layers of composite semiconductors attached to the cell silicon. To get an idea, the thickness of these layers would be one-twentieth of the thickness of a human hair.

In its operation, it is derived that visible sunlight is absorbed into an upper cell composed of gallium-indium and phosphorus, which we find as GaInP in the periodic table, infrared light is housed in a base of gallium-arsenic, GaAs, and the longer wavelengths in silicon are housed in a subcell. This would greatly increase the efficiency of silicon solar cells.

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Technical basics.

In order to capture a third of the sunlight and convert it into electrical energy, the researchers used a microelectronic process, this procedure is called “Direct bay connection or direct bay link”; This technique makes it possible to transfer a few micrometers of semiconductor materials from groups III and V, those previously described as GaInP and GaAs, directly onto the silicon.

After the activation of the plasma, the two surfaces are pressed against each other, which makes it possible to join the layer of groups III and V with those of silicon, thus forming a monolithic device.

The structure on the outside does not show the complexity of the inside, the cell has a simple front and back side, the contact just like a conventional silicon solar cell and therefore it can be integrated into photovoltaic modules of the same way.

Previous results.

This advance is in addition to a series of previous research results in the same field. In November 2016, researchers from the solar field of Friborg, in collaboration with the EVG team, demonstrated the efficiency of 30.2%, to later increase this result to 31.3% in March 2017, they have now succeeded Once again, reaching a record 33.3%, this result led to the recognition of the Green Tec jury, in the 2018 awards, being nominated among the top three in the “ energy ” category.