Thermophotovoltaic (TPV) systems offer an efficient way to directly convert thermal energy into electricity using the radiation emitted from a high temperature source. Compared to the conventional photovoltaic (PV) systems, TPVs have additional elements such as filters to tailor and shape the radiated energy impinging on the PV cell to improve the conversion efficiency. High contrast grating (HCG) structures are integrated within the combustor walls which act as a selective filter. The filter plays a major role by suppressing the sub-band gap radiation and reflecting it back to the combustion source. Typically, amorphous silicon (a-Si) periodic gratings with quartz as a substrate material are optimized for gallium antimonide (GaSb) PV cells. In this work, we have carried out detailed Multiphysics simulations to study the performance of GaSb, Si and InGaAsSb PV cells when operating in a micro combustor emitting non uniform radiation source operating in a temperature range of 500–2000 K. Results show that the proposed TPV system can have a power density of 250 mW/cm2 using GaSb PV cell. Further, significantly more photons can be converted to useful power with a higher cut-off wavelength PV cell such as InGaAsSb. Therefore, the power density can be as high as 410 mW/cm2. This study shows that the TPV systems employing low bandgap PV cells can have > 20 times higher power density compared to conventional silicon PV cells. © 2022 Elsevier Ltd