Scintillator Materials Characterization for Alpha Photovoltaic Energy Converters

Absolute light yield and radiation damage resilience were calculated and measured in ten scintillators suitable for use in alpha-photovoltaic energy conversion devices. The scintillators were exposed to alpha fluences of 10¹⁰ - 10¹⁵ ions/cm² to experimentally measure long-term damage to these materials. Scintillator light yield was calculated from IV curves in a calibrated InGaP photovoltaic diode. CsI:Tl had the largest initial light yield (4.8 kph/MeV) of all scintillators evaluated. An alpha fluence of 8.6 × 10¹⁴ ions/cm² reduced the light yield by 90% in CsI:Tl. The initial system efficiency of CsI:Tl on InGaP was measured to be 0.23%. Alpha-photovoltaic energy conversion devices with this initial system efficiency comprised of 1 mCi (3.7 × 10⁷ alphas/s) of ²⁴¹Am on CsI:Tl scintillators mounted on InGaP PIN photovoltaic diodes will produce 747.9 nW of electrical power. The power output from alpha stimulated CsI:Tl is 50% better than the conventional ZnS:Ag scintillator when used with an InGaP energy converter.