At high temperatures, wide-bandgap solar cells perform better than low-bandgap counterparts

Abstract Shockley–Queisser (SQ limit) has established that a bandgap of 1.4 eV is optimal for maximum photovoltaic efficiency at room temperature. Here, we performed a theoretical analysis of bandgap dependents performance under thermal stress by varying temperature from low 200 K to high 450 K. It is observed that the efficiency of the device is independent of bandgap variation (in simulated range 1.4–1.8 eV) at low temperature. At high-temperature efficiency shows dependence on bandgap, with wide bandgap outperforming narrow bandgap solar cells. At high temperatures, a wide bandgap’s superior performance over a narrow bandgap could be explained using the intrinsic carrier density and diode saturation current. Wide bandgap absorbers show lower intrinsic carrier density in turn low diode saturation current. The low value of diode saturation current for wide bandgap than narrow bandgap is responsible for the superior performance of wide bandgap absorbers. It is also observed that wide bandgap solar cells showed a low temperature coefficient which could also be explained by low diode saturation current for wide bandgaps. The design guidelines underlined in this work are useful for fabricating solar cells for high-temperature applications such as near-sun space missions.