SCIENTISTS from Stanford University have built the first solar cells made entirely from carbon, unlike current conventional photovoltaic devices which are made from silicon.
The researchers demonstrated a working thin film solar cell with all its components made of carbon. According to them, carbon has the potential to deliver high performance at low cost.
Being a thin film solar cell, the carbon materials are coated on the flexible substrate from solution. This may lead to future developments where coatings are applied directly onto surfaces like buildings, windows or cars.
This coating technique may also reduce manufacturing costs, due to the elimination of expensive tools and machines for manufacturing.
The experimental solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes.
Unlike typical thin film solar cells which make use of indium tin oxide (a scarce resource), the cell’s electrodes leverage graphene and single-walled carbon nanotubes, derived from carbon, a low-cost and abundant material.
For the photoactive layer, the researchers used material made of carbon nanotubes and "buckyballs", which are carbon molecules measuring one nanometer in diameter.
Unlike earlier “carbon solar cells” which just used carbon for the active layer in the middle, every component in the Stanford solar cell is made of carbon materials.
Of course, with a laboratory efficiency of less than one percent, the all-carbon solar cell is still a long way from commercialisation. Due to the material used, it only absorbs near-infrared wavelengths of light.
The researchers say they are working to improve efficiency by making each layer of the device very smooth, experimenting with carbon nanometerials which can absorb a broader range of wavelengths, etc.