Experimental and simulation investigations on the impact of non-uniform GaSb cells temperature in thermophotovoltaic systems

This study examines the effect of the non-uniform temperature distribution on the performance of GaSb thermophotovoltaic (TPV) cells under high radiation temperatures. Previous studies have primarily focused on the impact of overall cell temperature on the performance, indicating that as the cell temperature rises, so does the current. However, in practical thermophotovoltaic systems, a significant temperature gradient often develops because the upper surface of the cell is closely positioned to the emitter while the cooling system operates on the back side. A validated computational model reveals significant temperature gradients, with a 50 °C difference between the upper and lower surfaces of GaSb cells at a radiation temperature of 1200 °C. The effective photoelectric region, only a few micrometers thick, is highly sensitive to temperature changes, with its quantum efficiency dropping sharply above 80 °C, causing a decline in short-circuit current. Experimental results show the current initially increases slightly but then decreases significantly above 70 °C, while Voc steadily declines, in good agreement with the model. When the surface temperature of the cells increases from 20 to 95 °C, Isc decreases from 0.949 to 0.910 A, representing a reduction of 4.1%. Meanwhile, both Voc and Pmax decline by 13.1% and 21.1%, respectively. These findings emphasize the importance of considering localized thermal effects when optimizing TPV cell designs for high-performance applications.