Scientists at Stanford University in California have developed the first all-carbon solar cell, promising an alternative to the expensive materials currently used for photovoltaic devices.
Unlike rigid silicon solar panels, the latest thin film prototype is made of carbon materials that can be coated from solution.
The experimental solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes that are made of carbon, unlike other electrodes made of materials such as indium.
Stanford University chemical engineering professor and senior author of the study Zhenan Bao said that carbon is capable of delivering high performance at a low cost.
"Perhaps in the future we can look at alternative markets where flexible carbon solar cells are coated on the surface of buildings, on windows or on cars to generate electricity," Bao added.
Stanford University graduate student and co-lead author of the study Michael Vosgueritchian noted that the coating technique would reduce manufacturing costs.
"Processing silicon-based solar cells requires a lot of steps. But our entire device can be built using simple coating methods that don't require expensive tools and machines," Vosgueritchian said.
Bao and her colleagues replaced the silver and indium tin oxide used in conventional electrodes with one-atom-thick carbon sheets - 'grapheme', and single-walled carbon nanotubes that are 10,000 times narrower than a human hair.
"Carbon nanotubes have extraordinary electrical conductivity and light-absorption properties," Bao added.
For the active layer, the researchers used material made of carbon nanotubes and 'buckyballs' - ball-shaped carbon molecules just one nanometer in diameter.
Stanford researchers are also experimenting with carbon nanomaterials that can absorb more light in a broader range of wavelengths.
Image: the new all-carbon solar cell consists of a photoactive layer, which absorbs sunlight, sandwiched between two electrodes. Photo: courtesy of Stanford University.