SUPER SOLAR CELLS
While the first working photovoltaic (solar) cell was made of gold and selenium by American inventor Charles Fritts in 1883, silicon underpins most solar cell technology today and has dominated since the mid-20th century.
Silicon solar cells produce electricity when photons knock electrons from one layer of silicon semiconductor to another. These layers are doped with different atoms to give one layer an excess of electrons and the other a deficit. If the circuit is complete, the electrons can be captured to produce electricity. Many cells bundled together form a solar panel.
The first silicon solar cells’ efficiency hovered around 5%. Refining silicon’s purity and treating a solar cell’s surface to better absorb light have helped boost efficiency to around 25%. Commercially produced solar cells currently sit around 20%.
Meanwhile, other materials have been explored for solar cells, such as organic semiconductors. They’re made mostly made of carbon and hydrogen atoms.
There are benefits to organic solar cells. Organic semiconductors can be printed on flexible materials. Plus, they’re cheap.
What they’re not, though, is terribly efficient. Current organic solar cell technology has efficiencies around the 10% mark (although this is tipped to rise). So they’re not necessarily seen as a replacement for silicon solar cells but can be used alongside them.
For instance, organic solar cells were installed on rooftops in rural southern African villages that couldn’t access the electricity grid, giving those populations a safer and cheaper alternative to burning kerosene.