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High-efficiency photovoltaics using n-i-p semiconductor solar cells (SCs) are very promising for generating electrical power by utilizing solar radiation.
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These results suggest that the two-step photon up-conversion SC has a high potential for implementation in the next-generation high-efficiency SCs. We observe not only a dramatic increase in the additional photocurrent, which exceeds the reported values by approximately two orders of magnitude, but also an increase in the photovoltage. Efficient two-step photon up-conversion is achieved by introducing InAs quantum dots at the hetero-interface. The accumulated electrons at the hetero-interface are pumped upwards into the Al 0.3Ga 0.7As barrier by below-gap photons for GaAs. The below-gap photons for Al 0.3Ga 0.7As excite GaAs and generate electrons at the hetero-interface.
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Here we propose a two-step photon up-conversion SC with a hetero-interface comprising different bandgaps of Al 0.3Ga 0.7As and GaAs. The up-conversion of below-gap photons is very promising for generating additional photocurrent. Reducing the transmission loss for below-gap photons is a straightforward way to break the limit of the energy-conversion efficiency of solar cells (SCs).