The performance of GaSb cell and coupling effect of thermal-optical-electrical in thermophotovoltaic system

Radioisotope thermophotovoltaic (RTPV) systems, with their inherent high energy density and conversion efficiency, represent a promising power solution for deep space exploration. Under the strict heat dissipation constraints of deep space missions, different optical cavity configurations subject photovoltaic cells to complex thermo-optical coupling environments that significantly alter output performance. This study develops a simulated TPV system with a maximum emitter temperature of 1200 °C, a minimum PV cell coolant temperature of −20 °C, and an adjustable emitter-cell distance ranging from 4.5 cm to 9.5 cm. At 1000 °C, reducing the distance from 9.5 cm to 4.5 cm increases the GaSb cell's short-circuit current from 119.89 mA to 349.44 mA and open-circuit voltage from 385 mV to 450 mV, delivering a peak efficiency of 15.9% at 4.5 cm. When the emitter temperature reaches 1200 °C, the maximum system efficiency of 21.65% is achieved at 9.5 cm. Additional analysis of emitter spectral properties shows that lower surface roughness at 1200 °C yields higher conversion efficiency. The GaSb cell's fill factor distribution confirms that increasing the distance shifts the high fill factor (FF) region to higher operating temperatures. Under the given cooling configuration, high heat radiation flux leads to an increase in cell temperature and a decrease in fill factor. These results explicitly verify that PV cell performance is dominated by system-level thermo-optical coupling effects, providing valuable design references for future TPV system development.