High-efficiency thermophotovoltaic selective emitter enabled by a one-dimensional highly doped silicon grating and a photonic crystal stack
Phys. Rev. Applied 26, 024026 – Published 12 August, 2026
DOI: https://doi.org/10.1103/z9h4-6cg9
Abstract
We theoretically investigate the design of a highly efficient tunable selective emitter for thermophotovoltaic (TPV) applications that integrates two subsystems into a single device. The first subsystem consists of a one-dimensional highly doped silicon (HDSi) trapezoidal grating that acts as a broadband absorber, while the second subsystem is a multilayer structure (MS) composed of a stack of three photonic crystals (PCs) serving as a spectral filter. A simple, efficient, and fast numerical model is developed by transforming the grating into an equivalent multilayer stack using the effective medium approximation and the staircase approximation. To design the PC stack, and in contrast to previous works, we optimize the first photonic crystal and deduce the characteristics of the second and third PCs using appropriate scaling factors. The radiative properties of the full system are then calculated using the transfer matrix method. A parametric analysis is performed to optimize the emitter design for spectral matching with three commonly used TPV cells: GaSb, InGaAs, and InGaAsSb. It is found that using the same grating parameters and scaling factors for the MS, combined with tuning of the band gap wavelength, allows an excellent spectral match with all three TPV cells. The efficiency of the proposed selective emitter is evaluated using three standard formulations reported in the literature to enable direct comparison with prior work. The results show that the combined final system enables highly selective narrow band emission with efficient suppression of sub-band gap photons over a broad spectral range, up to , achieving high emitter efficiencies of 97.9% for the GaSb cell, exceeding 99% for InGaAs and InGaAsSb cells, and 77% at 1200 K for the three considered photovoltaic cells. Finally, the effect of high temperature on the spectral emission of the structure is investigated, considering the temperature dependence of the HDSi permittivity, and it is demonstrated that the structure exhibits good thermal stability at elevated temperatures.
