Gate-Tunable Hot Electron Extraction in a Two-Dimensional Semiconductor Heterojunction

IF 9.6 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters Pub Date : 2025-04-21 DOI:10.1021/acs.nanolett.4c06416

Chenran Xu, Chen Xu, Jichen Zhou, Zhexu Shan, Wenjian Su, Wenbing Li, Xingqi Xu, Kenji Watanabe, Takashi Taniguchi, Shiyao Zhu, Dawei Wang, Yanhao Tang

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Abstract

Hot carrier solar cells (HCSCs), harvesting the excess energy of hot carriers generated by above-band gap photoexcitation, are crucial for pushing the solar cell efficiency beyond the Shockley–Queisser limit, which is challenging to realize mainly due to fast hot-carrier cooling. By performing transient reflectance spectroscopy in a MoSe₂/hBN/WS₂ junction, we demonstrate the gate-tunable harvest of hot electrons from MoSe₂ to WS₂. By spectrally distinguishing hot-electron extraction from lattice temperature increase, we find that electrostatically doped electrons in MoSe₂ can boost hot-electron extraction density (n_ET) by a factor up to several tens. Such enhancement arises from the interaction between hot excitons and doped electrons, which converts the excess energy of hot excitons to excitations of the Fermi sea and hence generates hot electrons. Moreover, n_ET can be further enhanced by reducing the conduction band offset with an external electric field. Our results provide in-depth insights into the design of HCSCs with electrostatic strategies.

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二维半导体异质结的门可调谐热电子萃取

热载流子太阳能电池（HCSCs）可以收集带隙以上光激发产生的热载流子的多余能量，对于将太阳能电池效率提高到Shockley-Queisser极限之外至关重要，这主要是由于热载流子的快速冷却而难以实现。通过在MoSe2/hBN/WS2结中执行瞬态反射光谱，我们证明了从MoSe2到WS2的热电子的栅极可调谐收获。通过光谱区分晶格温度升高和热电子萃取，我们发现在MoSe2中静电掺杂电子可以将热电子萃取密度（nET）提高几十倍。这种增强来自于热激子与掺杂电子之间的相互作用，将热激子的多余能量转化为费米海的激发，从而产生热电子。此外，通过外加电场减小导带偏置可以进一步增强nET。我们的研究结果为静电策略设计HCSCs提供了深入的见解。

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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来源期刊

Nano Letters 工程技术-材料科学：综合

CiteScore

16.80

自引率

2.80%

发文量

1182

审稿时长

1.4 months

期刊介绍： Nano Letters serves as a dynamic platform for promptly disseminating original results in fundamental, applied, and emerging research across all facets of nanoscience and nanotechnology. A pivotal criterion for inclusion within Nano Letters is the convergence of at least two different areas or disciplines, ensuring a rich interdisciplinary scope. The journal is dedicated to fostering exploration in diverse areas, including: - Experimental and theoretical findings on physical, chemical, and biological phenomena at the nanoscale - Synthesis, characterization, and processing of organic, inorganic, polymer, and hybrid nanomaterials through physical, chemical, and biological methodologies - Modeling and simulation of synthetic, assembly, and interaction processes - Realization of integrated nanostructures and nano-engineered devices exhibiting advanced performance - Applications of nanoscale materials in living and environmental systems Nano Letters is committed to advancing and showcasing groundbreaking research that intersects various domains, fostering innovation and collaboration in the ever-evolving field of nanoscience and nanotechnology.