Efficiency limits of concentrated solar thermophotonic converters under realistic conditions: The impact of nonradiative recombination and temperature dependence

A concentrated solar thermophotonic converter (CSTC) that efficiently harvests the entire solar spectrum under non-ideal conditions is proposed. This device includes an optical concentrator, a solar absorber, a GaAs light- emitting diode (LED) on the hot side, and an InP photovoltaic (PV) cell on the cold side. The electric power generated by the PV cell is utilized to positively bias the heated LED, resulting in a substantial increase in LED emission power. A comprehensive theoretical model is developed to accurately predict the output electrical performance and overall energy conversion efficiency of the CSTC device, especially considering the impact of the nonradiative recombination and temperature dependence. The calculated results show that when the solar concentrating factor is 30, and the LED and PV cell voltages are 0.989 V and 1.13 V, respectively, the overall peak efficiency can reach 12.8% and the corresponding output power density is 384 mW cm-2, -2 , achieving performance metrics nearly 4 orders of magnitude higher than solar thermophotovoltaics (TPV). Additionally, increasing the solar concentration ratio and decreasing the thickness of the semiconductor materials can further improve the overall output performance. This work reveals that CSTC offers several advantages over solar TPV, including more efficient conversion of narrow-spectrum electroluminescence, higher radiated power from the LED emitter, and the ability to operate at lower solar concentrations and lower costs.