Metasurface Absorber–Emitter Pair-Integrated High-Efficiency Thermophotovoltaic System
Sumbel Ijaz, Do-Hyun Kang, Ahsan Sarwar Rana, Joohoon Kim, Muhammad Tariq Saeed Chani, Muhammad Zubair, Qammer H. Abbassi, Muhammad Qasim Mehmood, Junsuk Rho
Abstract
Solar technology, a major player in the energy domain, encounters the Shockley–Queisser (SQ) limit for solar cells. Solar thermophotovoltaics (STPV), consisting of an intermediate assembly of a sun-facing broadband absorber with a narrowband emitter at the back facing the band-matched PV cell, aim to circumvent this theoretical limit. We present a metasurface-based STPV system, achieving high efficiency across the range of temperatures and solar concentrations. Chromium (Cr)-based ultrathin (260 nm), square supercell-shaped meta-absorbers realize 99.91% peak absorption at 478 nm, with >80% absorption for a bandwidth of 1425 nm. Cr, with a melting point of 1907 °C, has been employed for its thermal stability, fabrication friendliness, and low cost. A gold-based cross-shaped meta-emitter is engineered for a highly selective spectral cutoff to match the InGaAs band gap (0.6365 eV), resulting in a high solar cell efficiency (η sc ) of 43.10%. With solar concentrations from 500× to 4500× at 500 °C, the intermediate efficiency (η I ) ranges from 99.81 to 99.94%. The metasurface absorber/emitter pair has been fabricated, with experimental results aligning with simulations. The system achieves 43.07% solar-to-electric efficiency at 500 °C and 4500 suns, maintaining over 41% until 1102 °C. Based on its compactness, polarization insensitivity, heat tolerance, and wide-angle stability, the design is highly suitable for STPV applications.