Fraunhofer ISE tops 31.3 % efficiency record for a new type of solar PV cell in only a couple of months
In November 2016, Fraunhofer ISE (Freiburg, Germany) reached a record efficiency for a triple-junction solar cell made of III-V and silicon material.
Now, in the short amount of time, the researchers in Freiburg have surpassed their own record. Their newest result boasts an efficiency of 31.3 percent for a fully integrated silicon-based multi-junction solar cell.
The outer appearance of the new solar cell looks no different than a conventional silicon solar cell.
With a simple front and rear contact, the record solar cell can be integrated into photovoltaic modules in the same manner.
Direct wafer bonding
In comparison, the highest efficiency measured to date for a pure silicon solar cell is 26.3 percent, and the theoretical efficiency limit is 29.4 percent.
The researchers used a “direct wafer bonding” process to transfer a few micrometers of III-V semiconductor material to silicon, a well-known process in the microelectronics industry.
After plasma activation, the subcell surfaces are bonded together in vacuum by applying pressure. The atoms on the surface of the III-V subcell form bonds with the silicon atoms, creating a monolithic device.
SOURCE: Fraunhofer ISE through Solarserver