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^1,2, lasers^3,4,5 and quantum technologies^6,7, among others^8,9,10. 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.

分子间距离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作为聚集体或稀释在异质基质中的单分子使用。近几十年来，它们在各种应用中引起了极大的研究兴趣，包括发光二极管^1,2 、激光器^3,4,5和量子技术^6,7等^8,9,10 。然而，对于这些分子在聚集状态和稀释状态之间的行为仍然存在知识差距。在这里，我们报告了一种前所未有的分子聚集相，它在具有接近平衡距离的二维杂化钙钛矿超晶格中形成，我们将其称为单分子类聚集体（SMA）。通过实现二维超晶格，有机发射体保持接近，但令人惊讶的是，它们保持电子隔离，从而产生接近一致的光致发光量子产率，类似于单分子的光致发光量子产率。此外，钙钛矿超晶格内的发射器表现出很强的排列和类似于聚集体的致密堆积，允许观察鲁棒的定向发射、显着增强的辐射复合和高效的激光发射。分子动力学模拟与单晶结构分析强调了二维晶格中分子的内部旋转和振动自由度对于创建独特的 SMA 相的关键作用。这种二维超晶格统一了单分子和聚集体的矛盾特性，从而为先进的光谱和光子应用提供了令人兴奋的可能性。