Modeling and Performance of Microscale Thermophotovoltaic Energy Conversion Devices

We analyze the feasibility of energy conversion devices that exploit microscale radiative transfer of thermal energy in thermophotovoltaic devices. By bringing a hot source of thermal energy very close to a receiver fashioned as a pn-junction, the near-field effect of radiation tunneling can enhance the net power flux. We use the fluctuational electrodynamic approach to microscale radiative transfer to account for the spacing effect, which provides the net transfer of photons to the receiver as a function of the separation between the emitter and receiver. We calculate the power output from the microscale device using standard thermophotovoltaic device relations. The results for the performance of a device based on indium gallium arsenide indicate that a ten-fold increase in power throughput may be realized with little loss in efficiency. Furthermore, we develop a model of the microscale device itself that indicates the influence of semiconductor band-gap energy, carrier lifetime, and doping.