Structural modulation of atomically precise lanthanide clusters for enhanced near-infrared photoluminescence quantum yield

Near-infrared luminescent lanthanide materials hold significant importance in the fields such as optoelectronics and information processing. However, their luminescence efficiency is severely constrained by multiple factors, including vibrational quenching, crystal field effects, and structural symmetry. In recent years, emerging lanthanide clusters featuring atomically precise structures have offered promising pathways to overcome these constraints and achieve efficient near-infrared (NIR) luminescence. Here, we successfully synthesized two distinct crystalline compounds (Nd-1 and Nd-2) via a stepwise substitution strategy, allowing for the modulation of the luminescence behavior of Nd 3+ ions. Complete substitution with the pentafluorobenzoic acid ligand results in Nd-2 exhibiting higher structural symmetry and fewer nonradiative relaxation pathways. These structural optimizations lead to a significant improvement in luminescence efficiency, with Nd-2 exhibiting a solid-state near-infrared photoluminescence quantum yield (PLQY) of 1.12%, a substantial enhancement compared to conventional Nd 3+ -based complexes. The underlying modulation mechanism was elucidated through application of Judd-Ofelt theory, crystal field analysis, and temperature-dependent photophysical investigations. This work reveals the intrinsic relationship between the structure and the luminescence behavior, providing a novel approach for designing high-efficiency NIR luminescent materials.