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Abstract Engineering a material's work function is of central importance for many technologies and in particular electron emitters used in high‐power vacuum electronics and thermionic energy converters. A low work function surface is typically achieved through unstable surface functional species, especially in high power thermionic electron emitter applications. Discovering and engineering new materials with intrinsic, stable low work functions obtainable without volatile surface species would mark a definitive advancement in the design of electron emitters. This work reports evidence for the existence of a low work function surface on a bulk, monolithic, electrically conductive perovskite oxide: SrVO3. After considering the patch field effect on the heterogeneous emitting surface of the bulk polycrystalline samples, this study suggests the presence of low work function (≈2 eV) emissive grains on SrVO3surface. Emission current densities of 10–100 mA cm–2at ≈1000 °C, comparable to commercial LaB6thermionic cathodes, indicative of an overall effective thermionic work function of 2.3–2.7 eV are obtained. This study demonstrates that perovskites like SrVO3may have intrinsically low work functions comparable to commercialized W‐based dispenser cathodes and suggests that, with further engineering, perovskites may represent a new class of low work function electron emitters.
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This content will become publicly available on March 1, 2026
Near-field enhanced solid-state thermionic power generation
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.
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- Award ID(s):
- 2044049
- PAR ID:
- 10636324
- Publisher / Repository:
- Applied Physics Letters
- Date Published:
- Journal Name:
- Applied Physics Letters
- Volume:
- 126
- Issue:
- 11
- ISSN:
- 0003-6951
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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