Performance Analysis of GaSb Cell and Thermophotovoltaic System Under Near-Field Thermal Radiation

An energy transfer model of a thermophotovoltaic (TPV) system, considering the variation of GaSb cell parameters under the near-field thermal radiation, was constructed. The effects of emitter–cell distances with different cooling systems on cell parameters and TPV system performances were analyzed. The results show that if the cell temperature is set at 300 K, the required convective heat transfer coefficient of the cooling system should be as high as 8.1 × 10 5 W/(m 2 ·K), which is a severe requirement for the existing cooling system. As the cell temperature increases, the photocurrent density decreases, because the internal quantum efficiency decreases due to the decreasing carrier life. The photocurrent density is significantly affected by the emitter–cell distance, because the distance has a strong impact on the thermal radiation. Similarly, the open-circuit voltage decreases with the increasing cell temperature and emitter–cell distance. To ensure a safe operation, the extreme emitter–cell distance is 12 nm for the best cooling system. When the emitter–cell distance decreases from 100 nm to 12 nm, the cell efficiency, which is around 0.25 at the far-field condition, decreases under the near-field thermal radiation, decreasing the TPV system efficiency which is obviously lower than that compared with the cell temperature of 300 K. Thus, the system performances with the cell temperature set at 300 K are overestimated. The results reveal that the variation of cell temperature needs to be considered to actually evaluate the performance of the near-field TPV system, and highly efficient cooling systems are urgently needed for the near-field TPV system.