High-efficiency thermophotovoltaic energy conversion enabled by a metamaterial selective emitter

Abstract

Thermophotovoltaics (TPV) is the process by which photons radiated from a thermal emitter are converted into electrical power via a photovoltaic cell. Selective thermal emitters that can survive at temperatures at or above ∼1000°C have the potential to greatly improve the efficiency of TPV energy conversion by restricting the emission of photons with energies below the photovoltaic (PV) cell bandgap energy. In this work, we demonstrated TPV energy conversion using a high-temperature selective emitter, dielectric filter, and 0.6 eV In 0.68 Ga 0.32 As photovoltaic cell. We fabricated a passivated platinum and alumina frequency-selective surface by conventional stepper lithography. To our knowledge, this is the first demonstration of TPV energy conversion using a metamaterial emitter. The emitter was heated to >1000°C, and converted electrical power was measured. After accounting for geometry, we demonstrated a thermal-to-electrical power conversion efficiency of 24.1 0.9% at 1055°C. We separately modeled our system consisting of a selective emitter, dielectric filter, and PV cell and found agreement with our measured efficiency and power to within 1%. Our results indicate that high-efficiency TPV generators are possible and are candidates for remote power generation, combined heat and power, and heat-scavenging applications.

A Multilayer Film Based Selective Thermal Emitter for Infrared Stealth Technology

“…A TPV system is an electrical generator that converts heat radiation energy into electrical energy with high efficiency. Since only a specific waveband of thermal radiation from the system can be converted to electricity, a proper spectral‐matched selective emitter, which has a thermal radiation peak in the near‐infrared range and emits little energy at nonconvertible wavebands, is needed for high‐efficiency conversion and reducing waste heat . In addition, by utilizing multilayer films or metamaterials, researchers have designed and fabricated radiative coolers that can cool themselves through thermal radiation to maintain a lower temperature than their surroundings .…”

Design of Multilayer Ring Emitter Based on Metamaterial for Thermophotovoltaic Applications

“…A heat source, a thermal radiator, and photovoltaic (PV) cells are the fundamental parts of a TPV system. The role of the thermal radiator is to convert solar or waste heat energies into thermal radiation, from which a PV cell generates electricity using the photovoltaic effect [2]. However, the conversion of electromagnetic energy to electrical power happens only when the photon energy is higher than the energy band gap of the PV cell.…”

Thermionic-enhanced near-field thermophotovoltaics for medium-grade heat sources

“…In TPV, thermally radiated photons are absorbed in a low-bandgap semiconductor and excite electron-hole pairs, which are selectively collected to produce an electrical current. Both TPV and TIC have already demonstrated higher conversion efficiencies than TEG at temperatures beyond 1000 ºC (~ 24 % for TPV 6,7 and ~ 11% for TIC 1 ). However, the power density is comparatively very low (e.g.…”