Researchers at Boston College have developed new solar cells that successfully use hot electrons to increase the cells’ power output. According to the scientists, the concept could lead to solar cells that break conventional efficiency limits.
A research team led by Michael Naughton, a physics professor at Boston College have created an ultra-thin solar cell (15-nanometer-thick), through which hot electrons can quickly pass before cooling. In conventional, thicker solar cells, only the “cooler” lower-energy electrons that have longer wavelengths can pass through.
When a conventional solar cell absorbs a high-energy photon, it produces a hot electron that quickly loses much of its energy as heat before it can pass through the cell and be used to generate electric energy. Although solar cells can be designed to use hot electrons and absorb high-energy photons, without being able to absorb low-energy photons. But the new solar cell design, however, can absorb both types to produce more energy.
Unlike conventional solar cells that are able to convert about 35% of sunlight into electric energy, the new cells could absorb low-energy photons as well as hot electrons o convert up to 67% of sunlight energy into electricity.