Luminescence thermochromism in atomically precise silver clusters: A comprehensive review

Stimuli-responsive materials have garnered significant attention in technology, sensors, and biological applications because of their quick response to various external factors. These include light, temperature, change in solvent, pressure fluctuations, mechanical friction, and alteration in pH values. Luminescence thermochromism, in particular, refers to the ability of materials to vary the color of their fluorescence emission as a function of temperature. Interestingly, silver clusters ranging from discrete to higher-dimensional structures show luminescence thermochromism due to strong argentophilic interactions and protecting ligands, affecting their emission position, intensity, and lifetime. These ultra-small materials possess superior photostability, biocompatibility, and low toxicity, holding great promise for potential applications. This review article provides valuable insights into the structural features of silver clusters for designing and developing luminescent thermochromic silver clusters. Additionally, this highlights the mechanisms behind luminescence thermochromism, including structural rigidity, competition between bathochromic and hypsochromic shifts, and thermally activated delayed fluorescence. The aim of this review is to inspire new ideas and concepts for developing new luminescent thermochromic silver cluster materials.