We studied the theoretical water splitting power conversion efficiencies (PCE) of tandem photovoltaic cells composed of two carrier multiplication (CM) layers connected in series. The effects of CM within each layer, solar concentration, a layer of water on top of the device, over potential, and varying absorber layer thickness on the PCE were studied under the detailed balance approach. Power conversion efficiencies of CM tandem cells far exceed that of the limit with no CM. In all cases that we studied CM can improve the power conversion efficiency. The highest theoretical PCE could be greater than 63% at 1000 suns. Even under more practical concentration level (10 suns) the PCE can exceed 50%. When including a 600 mV overpotential the PCE can reach 40%. Finally, I will discuss a proof-of-principle photoanode constructed of PbS QDs that exhibits carrier multiplication and produces 1 H2 for 1 photon for UV-photon wavelengths.

High theoretical conversion efficiencies using tandem cells that employ carrier multiplication for photochemical water splitting applications

256th National Meeting (2018)

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