Gamma-ray-driven photovoltaic cells via a scintillator interface

A new theoretical model of gamma ray photovoltaic cells is presented with calculations of efficiency η, open circuit voltage Voc, and maximum output power P0max. The model incorporates a scintillator interfaced between the high-energy nuclear isomer and the semiconductor materials of the photovoltaic cell. High-energy γ-photons, Eγ1=1.333 MeV and Eγ2=1.173 MeV, emanate from nuclear isomers Nickel-60m1/m2 of Nickel-60 in Cobalt-60 decay. The scintillator converts the γ-photons into large numbers of low-energy photons. The latter photons illuminate the semiconductor materials of the photo-voltaic cell. Such devices can have enhanced η, Voc, and a much longer operational life than those driven by Thorium-229m1/m2. Results are reported for devices with scintillators of various maximum emission wavelengths λmax and yields y. One mol of Cobalt-60, combined with a high-y and short-λmax scintillator, can produce Voc-10V and P0max of several hundred W/m2 to few times the AM0 power at about 70%. These are significant, indicating that these gamma ray photovoltaic cells have the potential to make a considerable contribution to electrical energy generation. Calculation are also performed using isomer Hafnium-178m2 (Eγ=2.4 MeV, T1/2=31 yr). (author)