Nano-scale vacuum gap thermo-tunnel devices for energy harvesting applications

The output power-density and the efficiency of thermo-tunnel devices are examinedas a function of inter-electrode separation, electrode work-function, and temperature. We find that these physical parameters dramatically influence the device characteristics, and under optimal conditions a thermo-tunnel device is capable of delivering a very high output power-density of ~10³ Wcm⁻². In addition, at higher temperatures, the heat-conversion efficiency of the thermo-tunnel device approaches ~10%, comparable to that of a thermoelectric generator. We therefore propose that thermo-tunnel devices are promising for solid-state thermal energy conversion.