${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ Thermophotovoltaic Cells Converting Low-Temperature Radiation into Electricity

Thermophotovoltaic cells, which convert low-temperature radiation into electricity, are of significance due to their potential applications in many fields. Here, ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cells, which work under the radiation from a blackbody, at a temperature of 300–480 K, are presented. The experimental results show that the cells can output electricity, even under a radiation temperature of 300 K. The band structure of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ heterojunctions and the defects in ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ thin films lower the conversion efficiency of the cells. It is also demonstrated that the resistivity of $\mathrm{Si}$ and the thickness of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ thin films have important effects on ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cells. Although the cells’ output power is small, this work provides a possible way to utilize low-temperature radiation.

Figure 1

Schematic structure of a ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cell.

Figure 2

SEM images of (a) surface morphology of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ thin films and (b) cross section of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ heterojunctions.

Figure 3

I-V curve of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ (resistivity of $\mathrm{Si}$ is 0.001 Ωcm) heterojunctions at room temperature.

Figure 4

(a) Relationship between the output current of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cells and wavelength (measured in the dark environment). (b) Reflection, transmission, and absorption of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cells. (c) Current density-voltage (J-V) characteristics. (d) Calculated efficiency (η) for ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cells under a radiation source at a temperature from 300 to 480 K.

Figure 5

(a) Ultraviolet photoelectron spectrometer’s spectrum of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ thin films. (b) The band diagram for the ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ heterojunction.

Figure 6

V_OC and I_SC of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ thermophotovoltaic cells with $\mathrm{Si}$ of different resistivity (0.5 and 0.001 Ωcm).

Figure 7

V_OC and I_SC of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$/$\mathrm{Si}$ (0.001 Ωcm) thermophotovoltaic cells with different sputtering times of ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ thin films under radiation from the heat source at 420 K.