Semiconductor-based selective emitter with sharp cutoff for thermophotovoltaic energy conversion

TL;DR

This paper presents a germanium-based selective emitter with sharp spectral cutoff designed for thermophotovoltaic energy conversion, demonstrating high spectral selectivity and potential efficiency improvements.

Contribution

It introduces a novel Ge-based selective emitter with optimized optical properties and confirms its spectral performance through simulations and measurements, advancing TPV emitter design.

Findings

Spectral emittance above 0.9 from 1 to 1.85 μm

Sub-bandgap emittance below 0.2 with sharp cutoff

Theoretical TPV efficiency analysis with GaSb cells

Abstract

Semiconductor emitter can possibly achieve sharp cutoff wavelength due to its intrinsic bandgap absorption and almost zero sub-bandgap emission without doping. A germanium wafer based selective emitter with front-side antireflection and backside metal coating is studied here for thermophotovoltaic (TPV) energy conversion. Optical simulation predicts the spectral emittance above 0.9 in the wavelengths from 1 to 1.85 um and below 0.2 in the sub-bandgap range with sharp cutoff around the bandgap, indicating superior spectral selectivity behavior. This is confirmed by excellent agreement with indirectly measured spectral emittance of the fabricated Ge-based selective emitter sample. Furthermore, the TPV efficiency by paring the Ge-based selective emitter with a GaSb cell is theoretically analyzed at different temperatures. This work will facilitate the development of the semiconductor-based selective emitters for enhancing TPV performance.