Solar thermionic energy converters with micro-gap spacers.

Abstract

We present a solar thermionic energy converter (STEC) incorporating interelectrode spacer structures for solar energy harvesting. We demonstrate the impact of spacer loss on the optimal performance and gap size of STECs with and without interelectrode spacers. Under a solar concentration factor of 100, we show that the maximum efficiency of STECs with a spacer (5.3%) is significantly lower than that of STECs without a spacer (8.7%) at different optimal gaps due to the interelectrode spacer that conducts heat parasitically. The optimal gap ranges from a few tenths of a micron to a few microns for STECs without spacers, while the optimal gap is around 8μm for STECs with spacers. Furthermore, the device operation with an internal support structure offers new, to the best of our knowledge, insights into the resulting behavior of different energy exchange mechanisms in STECs, which distinguishes them from devices without spacers.