Research shows that the way scientists look at solar power will be changing constantly in the coming years. Newly developed solar powered cells may soon outperform conventional photovoltaic technology. Scientists from the National Renewable Energy Laboratory (NREL) have demonstrated the first solar cell with external quantum efficiency (EQE) exceeding 100 percent for photons with energies in the solar range. (The EQE is the percentage of photons that get converted into electrons within the device.)
While traditional semiconductors only produce one electron from each photon, nanometer-sized crystalline materials such as quantum dots avoid this restriction and are being developed as promising photovoltaic materials. An increase in the efficiency comes from quantum dots harvesting energy that would otherwise be lost as heat in conventional semiconductors. The amount of heat loss is reduced and the resulting energy is funneled into creating more electrical current.
By harnessing the power of a process called multiple exciton generation (MEG), the researchers were able to show that on average, each blue photon absorbed can generate up to 30 percent more current than conventional technology allows. MEG works by efficiently splitting and using a greater portion of the energy in the higher-energy photons. The researchers demonstrated an EQE value of 114 percent for 3.5 eV photons, proving the feasibility of this concept in a working device.
This could mean solar panels that produce power at much cheaper rates than non-renewable sources!
While traditional semiconductors only produce one electron from each photon, nanometer-sized crystalline materials such as quantum dots avoid this restriction and are being developed as promising photovoltaic materials. An increase in the efficiency comes from quantum dots harvesting energy that would otherwise be lost as heat in conventional semiconductors. The amount of heat loss is reduced and the resulting energy is funneled into creating more electrical current.
By harnessing the power of a process called multiple exciton generation (MEG), the researchers were able to show that on average, each blue photon absorbed can generate up to 30 percent more current than conventional technology allows. MEG works by efficiently splitting and using a greater portion of the energy in the higher-energy photons. The researchers demonstrated an EQE value of 114 percent for 3.5 eV photons, proving the feasibility of this concept in a working device.
This could mean solar panels that produce power at much cheaper rates than non-renewable sources!
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