Study on the series resistance of betavoltaic batteries

The series resistance (Rs) is one of the essential factors that affect the performance of betavoltaic batteries. However, the Rs value of betavoltaic batteries tends to be anomaly high when it is extracted from the IV characteristic curve. To explore the reasons for this phenomenon, different injection conditions and their impacts on Rs of betavoltaic and photovoltaic cells were compared and analyzed, since photovoltaic cells have an in-depth study on Rs and have similar principles to betavoltaic cells. The results show that the Rs will be significantly affected by the injection conditions, and the high resistance of the depletion region under low level radiation injection of betavoltaic batteries is the main reason for their high Rs. The effect of high Rs on betavoltaic battery’s performance was further explored, and the results show that the IV characteristic curve will be distorted obviously when Rs is close to or higher than the shunt resistance and it thus leads to a significant decrease in the battery’s fill factor and energy conversion efficiency. The effect of the input power on Rs should be considered in the future analysis of betavoltaic batteries. This work provides theoretical support for the parameter analysis of betavoltaic batteries.