Coordination-induced emission enhancement in gold-nanoclusters with solid-state quantum yields up to 40% for eco-friendly, low-reabsorption nano-phosphors

• Published in: Scientific reports Vol. 9; no. 1; p. 4053
• Main Authors: Huang, Hsiu-Ying, Cai, Kun-Bin, Talite, Maria Jessabel, Chou, Wu-Ching, Chen, Po-Wen, Yuan, Chi-Tsu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 11-03-2019; Nature Publishing Group
• Subjects: 639/301/1019/482; 639/624; 639/624/399/354; 639/624/400; Glutathione; Gold; Heavy metals; Humanities and Social Sciences; multidisciplinary; Photons; Quantum dots; Reabsorption; Science; Science (multidisciplinary); Solvents
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-40706-3

Colloidal quantum dots (CQDs) have gained much attention as light-emitting materials for light-conversion nano-phosphors and luminescent solar concentrators. Unfortunately, those CQDs involve toxic heavy metals and frequently need to be synthesized in the hazardous organic solvent. In addition, they suffer from severe solid-state aggregation-induced self-quenching and reabsorption losses. To address these issues, here we prepare Zn-coordinated glutathione-stabilized gold-nanocluster (Zn-GSH-AuNCs) assemblies without involving heavy metals and organic solvent. Unlike GSH-AuNCs dispersed in an aqueous solution with poor photoluminescence quantum yields (PL-QYs, typically ~1%), those Zn-GSH-AuNCs powders hold high solid-state PL-QYs up to 40 ± 5% in the aggregated state. Such Zn-induced coordination-enhanced emission (CEE) is attributed to the combined effects of suppressed non-radiative relaxation and enhanced charge-transfer interaction. In addition, they also exhibit a large Stokes shift, thus mitigating both aggregation-induced self-quenching and reabsorption losses. Motivated by these photophysical properties, we demonstrated white-light emission from all non-toxic, aqueous-synthesis nano-materials.