Effect of material parameters on the open-circuit voltage in a GaInAsSb thermophotovoltaic cell

In this paper, a numerical simulation on the open-circuit voltage (VOC) of the P-GaSb window/P-Ga0.8In0.2As0.18Sb0.82 emitter/N-Ga0.8In0.2As0.18Sb0.82 base/N-GaSb structure thermophotovoltaic (TPV) cell is performed and an analysis of the effects of device parameters on VOC is presented. The simulations are carried out with the fixed spectral control filter and for the radiator temperature of Trad = 950 °C, cell temperature of Tdio = 27 °C, the radiation photons are injected from the front P-region. The thick P-Ga0.8In0.2As0.18Sb0.82 emitter with the longer minority carrier diffusion length is the main optical absorption region. The simulated results are compared with the available experimental data, and a good agreement is obtained. The effects of the layer thickness, carrier concentration, injection level and main recombination mechanisms (e.g. the radiative, Auger, bulk Shockley-Read-Hall (SRH) and surface recombination) of the P-Ga0.8In0.2As0.18Sb0.82 emitter and N-Ga0.8In0.2As0.18Sb0.82 base on VOC are analyzed. It indicates that the parameters of the emitter region have stronger effect than that of the base region on VOC. Dependence of VOC on the material parameters of P-GaSb window layer is also analyzed, both the carrier concentration and thickness of P-GaSb window layer have effect on VOC. Moreover, adding a back surface reflector (BSR) to the TPV cell can increase VOC.