Recycling backscattered β rays in planar betavoltaic batteries using the double-sided structure

Backscattering of β rays is one significant part of energy losses in betavoltaic batteries. However, few works have been carried out on this basic physical process and no guidance has been provided to minimize the impact of the backscattered electrons on the efficiencies of betavoltaics. In this work, a double-sided structure is proposed to recycle the backscattered electrons and reduce the backscattering loss. A systematical investigation has been conducted to minimize the backscattering loss in planar betavoltaic batteries. The double-sided structure has great advantages for utilizing the multiple times backscattering of electrons between the radioactive source and the semiconductor unit and for recycling the backscattered electrons. Our results show that thin source layers, high-energy sources, and sources with smaller effective atomic numbers can enhance the recycling effect and reduce the backscattering loss. 147Pm2O3 sources with the highest emitting energy and 14C(PMMA) sources with the lowest effective atomic number can recycle the most backscattered energy using the double-sided structure with a thin source layer. The method and the suggestions proposed in this work can be greatly useful in the battery design as well as other scenes where the electron backscattering should be considered.