Scientists at Stanford University have developed a thin film solar cellprototype made entirely of carbon, making it a promising alternative to the increasingly expensive materials used in traditional solar cells.
Carbon has the potential to deliver high performance at a low cost and is Earth-abundant, according to the Stanford researchers. Conventional solar cells are primarily made out of ridged silicon and use rare metals for conductors, where as the Stanford cells are entirely made with flexible and inexpensive carbon materials. The carbon materials can be coated from solution. Others have previously claimed to have developed all-carbon solar cells, but in those cases the use of carbon was limited to the middle active layer say the scientists.
Like a conventional solar cell, the Stanford prototype employs a photo-active layer that collects sunlight. That layer is sandwiched between two electrodes, and the flow of electrons from the photo-active layer to the electrodes creates the electrical current.
Carbon nanotubes have significantly better electrical conductivity and light absorption properties and would allow for easier production than conventional cells. One drawback of the all-carbon prototype is that it still has an efficiency of less than 1 percent – much lower than commercially available solar cells. The researchers are currently experimenting with a wide variety of carbon nanomaterials, looking to inprove the efficiency.
Even though the efficiency is still not up to scratch, the new solar solar cells have a significant advantage; they operate well under extreme conditions. Carbon is a very resilient material that can remain stable at high temperatures where other cells would stop working.
The results were published on Wednesday in the online edition of the journal ACS Nano.