Fabrication and testing of an infrared spectral control component for thermophotovoltaic power conversion applications

Abstract

Thermophotovoltaic (TPV) power conversion is the direct conversion of thermal radiation to electricity. Conceptually, TPV power conversion is a very elegant means of energy conversion. A thermal source emits a radiative spectrum, which is incident upon a photovoltaic (PV) diode. The PV diode then converts some of the incident photons to electricity. The photons which are converted to electricity have energies greater than the electronic bandgap of the material from which the PV diode is fabricated. Unfortunately the thermal sources used in TPV systems are typically broadband, meaning that a significant amount of the emitted radiation cannot be converted to electricity because the photons are not energetic enough to produce electron-hole pairs in the PV diode. This unconvertible radiation is dissipated as heat in the PV diode and represents a very large loss in a TPV system's conversion efficiency. This thesis describes the development of a spectral control component which can be used to filter the radiation emitted from a TPV system's thermal source, such that only convertible radiation is incident upon the PV diode. The theoretical analysis of filter designs based on a Si/SiO₂ dielectric stack is described in this text. The methods and processes used to fabricate physical samples of the spectral control component are discussed. The results of the spectral analysis of the physical samples are documented and a comparison between the predicted performance of the filter designs and the measured performance of the fabricated filter samples is made.