New Concept of Hot Carrier Solar Cells

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Alternative hot carrier solar cell with energy filtering based on thermionic emission The presented invention describes a method for increasing the efficiency of solar cells of so-called hot carrier at more than 30 by the rapid separation of hot electrons and holes in each band prior to cooling. The object is solved by the use of a specially adapted for this purpose a double hetero structure which has never been used for the separation of the hot carrier in a hot carrier solar cell. Theoretical guess - Approximations: - No recombination (because it is -slow- as compared with cooling) - No carrier cooling by photons (this influence is not of interest here) - Parabolic bands / effective mass (no details of a particular material are of interest here) - Non-degenerated semiconductors Solution- particle and energy conservation - The calculated efficiency should be considered as a fraction of the thermodynamically achievable one (60/85) - Optimal band offset is about 0.79 eV while Erest equal kTRT - The efficiency increases with illumination intensity increasing.


Benefits: - Fast energy filtering - Simple structure - lower cost - Tolerance against thickness variations - smooth technological transition from conventional DHS solar cells Drawback: slightly lower VOC due to extraction of too hot carriers... Open questions: - What are the optimal band offsets for DEC1 and DEV2 - How much energy gets lost due to rough energy filtering

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