In this work, we demonstrate that in parallel with the one existed at high doping concentration, there also exists an optimal combination of the transport properties of a thermoelectric material at low doping concentration as the curve of the relationship between electrical conductivity and doping concentration is rigidly shifted toward lower doping concentration without disturbing the Seebeck coefficient and the thermal conductivity. Based on this finding, a new concept for thermocouple design is developed to improve the thermocouple’s efficiency and power output. The analytical model developed for the new thermocouple indicated that its efficiency and power output can be more than tripled as compared to those of the original design. A single thermocouple made of Silicon semiconductors was simulated numerically using different sets of input parameters. The results showed that the new thermocouple’s efficiency and power output can be improved significantly.