Gammavoltaic Device with a High Light Yield Scintillator Interface

Radiovoltaic devices convert ionizing radiation from radioisotopes to electric power. Alphavoltaics and betavoltaics are most common but are limited in power density, whereas harvesting high power density gamma emitting radioisotopes is challenging because gamma-ray penetration depths far exceed carrier diffusion lengths. However, an indirect gammavoltaic, with a high light yield single crystal scintillator interface, can absorb a high proportion of an incident gamma flux and scintillate a large multiplicity of low-energy, near-monoenergetic photons to be harvested by a spectrally tuned photovoltaic cell. Owing to the resonance between the photovoltaic absorption spectra and the scintillation emission, photovoltaic conversion efficiencies can far exceed the Shockley-Queisser limit for solar spectrum harvesting. Preliminary experiments at ETH Zürich and the Paul Schreier Institute using a crude gammavoltaic with a 3.8 cm thick SrI₂:Eu single crystal scintillator interface and a perovskite photovoltaic cell with a non-resonant absorption peak, under 25 TBq ¹³⁷Cs gamma radiation (662 KeV), achieved a device power conversion efficiency—including gamma attenuation losses—of 0.62%. Light yield being inversely proportional to the bandgap, current research is focused on the development of a low-temperature solution-grown high light yield, lanthanide-doped inorganic lead halide perovskite single crystal scintillator. In particular, we report on progress toward a lanthanide-doped cesium lead mixed halide single crystal growth method using temperature-dependent solubility in organic aprotic solvents.