Thermal radiation is one of the most universal physical phenomena, and its study has played a key role in the history of modern physics. Our understanding of this subject has been traditionally bas...

Radiative Heat Transfer

Nanophotonic systems, including photonic crystal microcavities and plasmonic metal nanoparticles, that are capable of changing the rate of spontaneous emission are reviewed and compared.

Modified spontaneous emission in nanophotonic structures

We present theoretical considerations as well as detailed numerical design of absorber and emitter for Solar Thermophotovoltaics (STPV) applications. The absorber, consisting of an array of tungsten pyramids, was designed to provide near-unity absorptivity over all solar wavelengths for a wide angular range, enabling it to absorb light effectively from solar sources regardless of concentration. The emitter, a tungsten slab with Si/SiO(2) multilayer stack, provides a sharp emissivity peak at the solar cell band-gap while suppressing emission at lower frequencies. We show that, under a suitable light concentration condition, and with a reasonable area ratio between the emitter and absorber, a STPV system employing such absorber-emitter pair and a single-junction solar cell can attain efficiency that exceeds the Shockley-Queisser limit.

/pdf/absorber-and-emitter-for-solar-thermo-photovoltaic-systems-3wp8y75pd5.pdf

Absorber and emitter for solar thermo-photovoltaic systems to achieve efficiency exceeding the Shockley-Queisser limit.

https://nanoptics.files.wordpress.com/2012/08/imenes-spectral-beam-splitting-technology-for-increased-conversion-efficiency-in-solar-concentrating-systems-a-review-semsc-2004.pdf

Spectral beam splitting technology for increased conversion efficiency in solar concentrating systems: a review

Theoretical efficiencies are derived in a detailed balance calculation for thermophotovoltaic solar energy conversion, where solar radiation is absorbed by an intermediate absorber, which emits radiation inside an evacuated housing towards a solar cell. For ideal components with no optical losses and only radiative recombination in the solar cell, maximal efficiencies are found of 85% for full concentration of the incident sunlight on a black absorber, and of 54% for no concentration and a selective absorber absorbing only for ? > 0.92 eV. This is considerably larger than the efficiency for directly illuminated solar cells with also only radiative recombination, the Shockley?Queisser limit, which is 41% for full concentration and 30% for no concentration. In order to approach efficiency limits for real TPV systems, several non-idealities have been introduced: (a) realistic assumptions about the geometry of the intermediate absorber, (b) optical losses of 5% for photons with energy below the band gap of the solar cell and (c) non-radiative recombination in the solar cell of the same amount as radiative recombination. This reduces the efficiency for non-concentrated sunlight to only 32.8%, but for very high concentrations of 10000 and above suitable absorber geometries still seem to allow efficiencies close to 60%.

http://iopscience.iop.org/article/10.1088/0268-1242/18/5/303/pdf

Theoretical limits of thermophotovoltaic solar energy conversion

A solar-electric system is proposed and discussed. This system uses concentrated mirrors focusing on a thermophotovoltaic (TPV) converter. Within the TPV converter the concentrated sunlight heats a refractory radiator. A silicon photovoltaic cell faces the radiator, receives incandescent radiation from it, and converts this radiation into electricity.

R.M. Swanson

Papers

A proposed thermophotovoltaic solar energy conversion system