Thermophotovoltaic

Thermophotovoltaics (TPV) is a solid-state energy conversion technology that generates electricity from thermal radiation. In a TPV system, a hot emitter radiates photons onto a photovoltaic (PV) cell. The PV cell converts photons with energy above its bandgap into electron–hole pairs, producing electrical power. The emitter and PV cell are typically separated by a vacuum or low-pressure gap to minimize nonradiative heat transfer, and the emitter temperature can range from several hundred to several thousand kelvin depending on the design.

The operating principle relies on spectral management. Only photons with energy greater than the cell’s bandgap contribute to power generation; photons with lower energy are not absorbed, while photons with energy much higher than the bandgap can cause excess heat in the cell. To improve efficiency, engineers use selective emitters or spectral filters to tailor the emitted spectrum to match the PV bandgap, and may employ optical mirrors or photonic structures to recycle or redirect emitted radiation. Near-field TPV explores nanoscale gaps between the emitter and cell to dramatically increase radiative transfer and potentially higher efficiencies.

Common TPV implementations use PV materials such as GaSb, InGaAs, InAs, or HgCdTe, chosen for bandgaps around the infrared range. The performance of a TPV system is influenced by emitter temperature, spectral matching, radiative losses, and thermal management of the PV cell. Real-world TPV devices face challenges including material stability at high temperatures, thermal losses, and system integration, but offer potential for waste-heat recovery, compact solar energy conversion, and space or remote power applications.