Novel composite semiconductor materials for plasma energy conversion systems

In this talk we discuss the realisation of photon-enhanced thermionic emission (PETE) effect for solar concentrator combining photovoltaic and thermionic processes in a single device leading to a significant increase in its efficiency. Porous silicon-based nanostructures are investigated and suggested for further PETE electrode realisation. The prototype PETE concentrator with semiconductor (GaN) electrodes is described, although it possess a critical drawback: the number of incident photons with energies exceeding the band gap of GaN (E_g = 3.3 eV) is less than 1 % of their total amount. Further research on porous silicon (PS) and PS-based nanocomposites is required, since it is possible to modify the E_g of such materials in a range from 1 to 3 eV due to the extensive capabilities for surface functionalisation and quantum confinement effect.

It is known that the development of anodes for thermionic plasma energy systems requires the creation of materials characterised with low electron work function (ϕ_a). This problem is traditionally solved by implementing alkali and alkaline-earth metal coatings, Cs in particular. We suggest the use of high electron affinity PS-based structures functionalised with silver nanoparticles and C₆₀-Ag fullerenols as a perspective alternative.