Thin-Film Architectures with High Spectral Selectivity for Thermophotovoltaic Cells

Abstract

Thermophotovoltaic (TPV) systems are a promising technology for distributed conversion of high-temperature heat to electricity. To achieve high conversion efficiency, the transport of sub-bandgap radiation between the thermal emitter and PV cell should be suppressed. This can be achieved by recycling sub-bandgap radiation back to the emitter using a spectrally selective cell. However, conventional TPV cells exhibit limited sub-bandgap reflectance. Here we demonstrate thin-film In0.53Ga0.47As-based structures with high spectral selectivity, including record-high average sub-bandgap reflectance (96%). Selectivity is enabled by short optical paths through a high-quality material fabricated using epitaxial lift-off, high-reflectance back surfaces, and optimized interference. In addition, we use a parallel-plate TPV model to evaluate the impact of specific structural features on performance and to optimize the cell architecture. We show that a dielectric spacer between InGaAs and the Au back surface is an important feature that enables a predicted TPV efficiency above 50% (with a power output of 2.1 W/cm2), significantly higher than current TPV devices. This work provides guidelines for the design of high-efficiency, low-cost TPV generators.

Ultraefficient thermophotovoltaic power conversion by band-edge spectral filtering

“…7. This improvement in reflectivity can be obtained by adding a layer of low refractive index dielectric between the rear gold layer and the semiconductor (49).…”

Performance of Ge and In0.53Ga0.47 as Thermophotovoltaic Cells under Different Spectral Irradiances

“…The cells were investigated under different radiation temperatures before and after optimizing the TPV cells for minimum optical losses. Since the paper's main focus is to study the intensity effect, optimization was only conducted for the base layer thicknesses, which is the main contributing factor [60], and the radiation temperature was at 1800 K. Furthermore, effective ARC such as MgF2/ZnS for the Ge cell and MgF2/ZnSe for InGaAs cell are employed to reduce the optical reflection losses at the surface of cells [37], [61]. The efficiency of Ge or InGaAs cells increases after the use of ARC due to the reduction of the incident light reflects at the front surface of the cell.…”

Multi-dimensional optimization of In0.53Ga0.47As thermophotovoltaic cell using real coded genetic algorithm

“…The TPV converters mainly utilize narrow bandgap (NB) semiconductor materials which allow them to harvest the maximum amount of infrared radiations (IRs). The advancement of nanotechnology and material science since 1990s have boosted the development of various NB TPV cells, such as germanium (Ge) 17 , indium arsenide (InAs) 18 , gallium antimonide (GaSb) 19 , indium gallium arsenide (InGaAs) 20 , indium gallium antimonide (InGaSb) 21 , indium gallium arsenide antimonide (InGaAsSb) 22 and indium arsenide antimonide phosphate (InAsSbP) 23 . In the last 3 decades of research in TPV, most researchers focus on the utilization of GaSb cell due to its narrow bandgap of 0.72 eV.…”