Mechanisms Leading to Losses in Conventional Betavoltaics and Evolution: Utilizing Composite Semiconductor With Infused Radioisotope for Efficiency Improvement

In this paper, we demonstrate remarkably improved efficiency over various conventional betavoltaics with critical energy loss problems. Radioactive sulfur (³⁵S) was uniformly infused within a semiconductor material (selenium) and volumetrically encapsulated in the harvesting betavoltaic cells. By eliminating or reducing the potential loss factors with this new method, highly efficient energy conversion was achieved compared with conventional approaches. First and second generation prototype devices were fabricated and tested. A maximum output power of 687 nW was obtained from the micropower source using 33.61 mCi of ³⁵S. The overall efficiency of the prototype device was 7.05%.