Improved performance of a thin-film multijunction thermal converter

This paper describes the improved performance of thin film multijunction thermal converters (TFMJTC) that has been developed by NMIJ and NIKKOHM Co. Ltd. For the former type TFMJTCs, a deterioration of thermocouples was observed. The degradation prevention has been completed by changing the design and fabrication process of the thin-film thermopile to improve the durability of the TFMJTCs. Long-term use of the improved TFMJTCs (e.g., more than 20 years) can be expected based on the Arrhenius model. The ac-dc transfer differences from 10 Hz to 1 MHz can be reduced to less than 10 μV/V by adjusting the input impedance.