Theoretical study on the Cs/Cs-O adsorbed graphene/semiconductor heterojunction anode for thermionic converters

Waste Disposal & Sustainable Energy Pub Date : 2024-04-29 DOI:10.1007/s42768-024-00191-5

Weiting Sun, Haoran Xu, Hao Qiu, Gang Xiao

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Abstract

Graphene/semiconductor heterojunction anodes can significantly enhance the output voltage by the photovoltaic effect. However, a significant challenge arises from the high intrinsic work function of heterojunction surfaces, which limits efficient electron emission. In this study, we explored the potential of low work function materials modified by Cs/Cs-O adsorption as anodes for thermionic (TI) converters through first principles calculations. The results demonstrate that the work functions of the graphene/MoS₂ and the graphene/n-type Si surfaces with only Cs coating can decrease to 1.48 eV and 2.46 eV, respectively. The multiple Cs-O atoms co-adsorption enhances the dipole moment, resulting in a further reduction of the work function of the graphene/MoS₂ surface to 1.25 eV. In addition, the impact of work function on the performance of TI converters is revealed by using concentrated solar energy as heat source. The highest conversion efficiency achieves 15.25% for the Cs-4O: Gr/MoS₂ anode. This study establishes a robust foundation for further advancement of the TI converters with graphene/semiconductor heterojunction anodes.

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用于热离子转换器的 Cs/Cs-O 吸附石墨烯/半导体异质结阳极的理论研究

石墨烯/半导体异质结阳极可通过光伏效应显著提高输出电压。然而，异质结表面的高固有功函数限制了电子的有效发射，这是一个重大挑战。在本研究中，我们通过第一性原理计算探索了经 Cs/Cs-O 吸附改性的低功函数材料作为热离子（TI）转换器阳极的潜力。结果表明，仅有 Cs 涂层的石墨烯/MoS2 和石墨烯/n 型硅表面的功函数可分别降至 1.48 eV 和 2.46 eV。多个 Cs-O 原子的共吸附增强了偶极矩，使石墨烯/MoS2 表面的功函数进一步降低到 1.25 eV。此外，通过使用聚光太阳能作为热源，还揭示了功函数对 TI 转换器性能的影响。Cs-4O: Gr/MoS2 阳极的最高转换效率达到了 15.25%。这项研究为进一步推进采用石墨烯/半导体异质结阳极的 TI 转换器奠定了坚实的基础。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Waste Disposal & Sustainable Energy

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