Betavoltaic Cells Using P3HT Semiconductive Conjugated Polymer

The need for extreme-duration light-weight power sources for space applications motivates the study and development of polymer-based betavoltaics. The betavoltaic device, based on the semiconductive polymer-fullerene blend of poly(3-hexylthiophene): indene-C₆₀ bisadduct (P3HT:ICBA), is demonstrated here for the first time. Both direct and indirect energy conversion methods were explored. For the indirect conversion method, a phosphor intermediate layer of cerium-doped yttrium aluminum garnet (Ce:YAG) was used on top of the polymer device. A high open circuit voltage of 0.56 V has been achieved in the betavoltaic device fabricated on a polyethylene terephthalate (PET) substrate with indirect energy conversion at 30-keV electron kinetic energy. The maximum output electrical power of 62 nW was achieved at 30-keV input electron beam (e-beam) energy. The highest betavoltaic power conversion efficiency of 0.78% was achieved at an e-beam energy of 10 keV. Using the thin PET substrate instead of a glass substrate for the polymer device and phosphor screen fabrication, the betavoltaic device performance has been significantly improved due to a reduction in physical distance between photon-generating Ce:YAG phosphor screen and photon-absorbing P3HT:ICBA layer. The use of the PET substrates helped by significantly decreasing the directional and external interaction losses.