Near-field enhanced solid-state thermionic power generation

Abstract

The lack of low-work function materials and the negative space charge effect have long prevented vacuum thermionic energy converters (VTECs) from becoming a practical means of power generation. Advancements in microfabrication have since provided solutions to these challenges, such as the suppression of negative space charge via a micro/nanoscale interelectrode vacuum gap distance, reigniting interest in VTECs as a potential clean energy technology. However, the limited operational lifetimes of many low-work function coatings have hindered their practical device-level implementation. Solid-state thermionic energy converters (SSTECs) have been proposed as a viable alternative to VTECs since they do not require an interelectrode vacuum gap or low-work function electrodes. Nevertheless, SSTECs still require a large temperature gradient between electrodes and are limited to low operating voltages. To address these limitations, we propose a near-field enhanced solid-state thermionic energy converter (NF-SSTEC), which leverages the advantages of SSTECs by eliminating the need for a large temperature gradient between the electrodes and increasing the range of possible operating voltages. We theoretically demonstrate conversion efficiencies of 16.8 % and power densities as high as 13.1 W cm−2 without needing a high-temperature gradient between the radiator and SSTEC. Additionally, we compare its performance under different radiation spectra, showing the potential for improvement via further optimization of the radiator.