法国巴黎城市大学Emmanuel Baudin团队研究了双曲极化子介导的电致发光和能量转移。2025年3月19日出版的《自然》杂志发表了这项成果。

在高电流下，一些材料可以发出超过白炽度的电磁辐射。这种现象被称为电致发光，导致可见光子的有效发射，是家用照明设备（例如发光二极管）的基础。原则上，电致发光可以导致被称为声子极化子的受限光物质激发的中红外发射，这是由光子与晶格振动（光学声子）的耦合引起的。特别是，范德华晶体六方氮化硼（hBN）中产生的声子极化子呈现双曲线色散，这增强了光-物质耦合。

因此，双曲声子极化子（HPhPs）的电致发光被提出作为hBN封装石墨烯晶体管内特殊辐射能量转移的解释。然而，由于HPhPs是局部受限的，它们在远场是不可接近的，因此，任何电致发光的迹象都是基于间接的电子特征，尚未得到直接观察的证实。

研究组展示了范德华异质结构内强偏置高迁移率石墨烯激发的HPhPs的远场中红外（波长约6.5μm）电致发光，并量化了通过材料的相关辐射能量传递。由于HPhPs在异质结构不连续处的弹性散射，远场中红外光谱揭示了HPhPs的存在。通过接收能量的基板的中红外高温测量来量化由此产生的辐射通量。在具有纳米级不均匀性的hBN中，这种辐射能量传递也被证明是减少的，这表明了电磁环境在这一过程中的核心作用。

附：英文原文

Title: Electroluminescence and energy transfer mediated by hyperbolic polaritons

Author: Abou-Hamdan, Loubnan, Schmitt, Aurlien, Bretel, Rmi, Rossetti, Sylvio, Tharrault, Marin, Mele, David, Pierret, Aurlie, Rosticher, Michael, Taniguchi, Takashi, Watanabe, Kenji, Maestre, Camille, Journet, Catherine, Toury, Brangre, Garnier, Vincent, Steyer, Philippe, Edgar, James H., Janzen, Eli, Berroir, Jean-Marc, Fve, Gwendal, Mnard, Gerbold, Plaais, Bernard, Voisin, Christophe, Hugonin, Jean-Paul, Bailly, Elise, Vest, Benjamin, Greffet, Jean-Jacques, Bouchon, Patrick, De Wilde, Yannick, Baudin, Emmanuel

Issue&Volume: 2025-03-19

Abstract: Under high electrical current, some materials can emit electromagnetic radiation beyond incandescence. This phenomenon, referred to as electroluminescence, leads to the efficient emission of visible photons and is the basis of domestic lighting devices (for example, light-emitting diodes)1,2. In principle, electroluminescence can lead to mid-infrared emission of confined light–matter excitations called phonon polaritons3,4, resulting from the coupling of photons with crystal lattice vibrations (optical phonons). In particular, phonon polaritons arising in the van der Waals crystal hexagonal boron nitride (hBN) present hyperbolic dispersion, which enhances light–matter coupling5,6. For this reason, electroluminescence of hyperbolic phonon polaritons (HPhPs) has been proposed as an explanation for the peculiar radiative energy transfer within hBN-encapsulated graphene transistors7,8. However, as HPhPs are locally confined, they are inaccessible in the far field, and as such, any hint of electroluminescence has been based on indirect electronic signatures and has yet to be confirmed by direct observation. Here we demonstrate far-field mid-infrared (wavelength approximately 6.5μm) electroluminescence of HPhPs excited by strongly biased high-mobility graphene within a van der Waals heterostructure, and we quantify the associated radiative energy transfer through the material. The presence of HPhPs is revealed by far-field mid-infrared spectroscopy owing to their elastic scattering at discontinuities in the heterostructure. The resulting radiative flux is quantified by mid-infrared pyrometry of the substrate receiving the energy. This radiative energy transfer is also shown to be reduced in hBN with nanoscale inhomogeneities, demonstrating the central role of the electromagnetic environment in this process.

DOI: 10.1038/s41586-025-08627-6

Source: https://www.nature.com/articles/s41586-025-08627-6