近日，美国普渡大学的Letian Dou&Brett M. Savoie及其研究团队取得一项新进展。经过不懈努力，他们发现二维晶格限域的类单分子聚集态。相关研究成果已于2024年9月11日在国际权威学术期刊《自然》上发表。

本研究报道了一种前所未有的分子聚集态，该聚集态在一种具有近平衡距离的二维杂化钙钛矿超晶格中形成，研究人员称之为类单分子聚集态（SMA）。通过构建二维超晶格，有机发光体得以彼此靠近，但令人惊讶的是，它们在电子上仍保持孤立，从而实现了接近单一分子的光致发光量子产率。

此外，钙钛矿超晶格中的发光体展现出类似聚集态的强定向排列和紧密堆积，使得可以观察到稳健的方向性发射、显著增强的辐射复合以及高效的激光效应。结合分子动力学模拟和单晶结构分析，本研究凸显了二维晶格中分子的内部旋转和振动自由度在形成独特的SMA态中的关键作用。这种二维超晶格融合了单分子和聚集态的矛盾特性，为先进的光谱学和光子学应用提供了激动人心的可能性。

据悉，分子间距离在很大程度上决定了有机物的光电性质。传统的有机发光分子通常以聚集态或单分子态（后者需稀释于外来基质中）被使用。近几十年来，这些分子因在发光二极管、激光器和量子技术等众多应用领域中的潜力而备受研究关注。然而，关于这些分子在聚集态与稀释态之间的行为，目前仍存在认知空白。

附：英文原文

Title: Two-dimensional-lattice-confined single-molecule-like aggregates

Author: Wang, Kang, Lin, Zih-Yu, De, Angana, Kocoj, Conrad A., Shao, Wenhao, Yang, Hanjun, He, Zehua, Coffey, Aidan H., Fruhling, Colton B., Tang, Yuanhao, Varadharajan, Dharini, Zhu, Chenhui, Zhao, Yong Sheng, Boltasseva, Alexandra, Shalaev, Vladimir M., Guo, Peijun, Savoie, Brett M., Dou, Letian

Issue&Volume: 2024-09-11

Abstract: Intermolecular distance largely determines the optoelectronic properties of organic matter. Conventional organic luminescent molecules are commonly used either as aggregates or as single molecules that are diluted in a foreigner matrix. They have garnered great research interest in recent decades for a variety of applications, including light-emitting diodes, lasers and quantum technologies, among others. However, there is still a knowledge gap on how these molecules behave between the aggregation and dilution states. Here we report an unprecedented phase of molecular aggregate that forms in a two-dimensional hybrid perovskite superlattice with a near-equilibrium distance, which we refer to as a single-molecule-like aggregate (SMA). By implementing two-dimensional superlattices, the organic emitters are held in proximity, but, surprisingly, remain electronically isolated, thereby resulting in a near-unity photoluminescence quantum yield, akin to that of single molecules. Moreover, the emitters within the perovskite superlattices demonstrate strong alignment and dense packing resembling aggregates, allowing for the observation of robust directional emission, substantially enhanced radiative recombination and efficient lasing. Molecular dynamics simulations together with single-crystal structure analysis emphasize the critical role of the internal rotational and vibrational degrees of freedom of the molecules in the two-dimensional lattice for creating the exclusive SMA phase. This two-dimensional superlattice unifies the paradoxical properties of single molecules and aggregates, thus offering exciting possibilities for advanced spectroscopic and photonic applications.

DOI: 10.1038/s41586-024-07925-9

Source: https://www.nature.com/articles/s41586-024-07925-9

来源：科学网  小柯机器人