Bi 2 Te 3 /Sb 2 Te 3 thermophotovoltaic cells for low temperature infrared radiation

The thermophotovoltaic cells which convert the low temperature (below 500 K) infrared radiation into electricity are of significance due to their potential applications in many fields. In this work, narrow bandgap Bi 2 Te 3 /Sb 2 Te 3 thin film thermophotovoltaic cells were fabricated, and the formation mechanism of Bi 2 Te 3 /Sb 2 Te 3 p-n heterojunctions was investigated. At room temperature, the heterojunctions are formed through the diffusion of electrons and holes along the same direction from n-type Bi 2 Te 3 thin films to p-type Sb 2 Te 3 thin films rather than conventional bi-directional diffusion. Because the strong intrinsic excitation generates a large number of intrinsic carriers which weaken the built-in electric field of the heterojunctions, their I-V curves become similar to straight lines. It is also demonstrated that Bi 2 Te 3 /Sb 2 Te 3 thermophotovoltaic cells can output electrical power under the infrared radiation from a low temperature heat source. Although the open-circuit voltage and the short-circuit current of the cells are low, this work provides a possible way to utilize the low temperature radiation.