Hassani Hamideh, Bousquet Eric, He Xu, Partoens Bart, Ghosez Philippe
Theoretical Materials Physics, Q-MAT, University of Liège, Liège, Belgium.
Department of Physics, University of Antwerp, Antwerp, Belgium.
Nat Commun. 2025 Feb 16;16(1):1688. doi: 10.1038/s41467-025-56791-0.
Polarons can naturally form in materials from the interaction of extra charge carriers with the atomic lattice. Ubiquitous, they are central to various phenomena such as high-T superconductivity, electrochromism, photovoltaics, photocatalysis or ion batteries. However, polaron formation remains poorly understood and mostly relies on historical models such as Landau-Pekar, Fröhlich, Holstein or Jahn-Teller polarons. Here, from advanced first-principles calculations, we show that the formation of intriguing medium-sized polarons in WO does not fit with traditional models but instead arises from the local undoing of distortive atomic motions inherent to the pristine phase, which lowers the bandgap through dynamical covalency effects and drives charge trapping. We introduce the concept of the anti-distortive polaron and rationalize it from a quantum-dot model. We demonstrate that anti-distortive polarons are generic to different families of compounds and clarify how this new concept opens concrete perspectives for a better control of the polaronic state and related properties.
极化子可通过额外电荷载流子与原子晶格的相互作用在材料中自然形成。它们无处不在，是诸如高温超导、电致变色、光伏、光催化或离子电池等各种现象的核心。然而，极化子的形成仍知之甚少，且大多依赖于诸如朗道 - 佩卡尔、弗罗利希、霍尔斯坦或杨 - 特勒极化子等传统模型。在此，通过先进的第一性原理计算，我们表明在WO中有趣的中等尺寸极化子的形成并不符合传统模型，而是源于原始相中固有扭曲原子运动的局部消除，这通过动态共价效应降低了带隙并驱动电荷俘获。我们引入了反扭曲极化子的概念，并从量子点模型对其进行了合理化解释。我们证明反扭曲极化子对于不同化合物家族具有普遍性，并阐明了这一新概念如何为更好地控制极化子态及相关性质开辟了具体前景。
