Thermionic converters based on nanostructured carbon materials
Contributors: Franz A.M. Koeck, Yunyu Wang, and Robert J. Nemanich
ABSTRACT
Thermionic energy converters are based on electron emission through thermal excitation and collection where the thermal energy is directly converted into electrical power. Conventional thermionic energy converters based on emission from planar metal emitters have been limited due to space charge. This paper presents a novel approach to thermionic energy conversion by focusing on nanostructured carbon materials, sulfur doped nanocrystalline diamond and carbon nanotube films as emitters. These materials exhibit intrinsic field enhancement which can be exploited in lowering the emission barrier, i.e. the effective work function. Moreover, emission from these materials is described in terms of emission sites as a result of a non‐uniform spatial distribution of the field enhancement factor. This phenomenon can prove advantageous in a converter configuration to mitigate space charge effects by reducing the transit time of electrons in the gap due to an accelerated charge carrier transport.