Aggregation-induced emission of silver nanoclusters induced by Li+ for white light emitting diodes

Abstract

Because of the increasingly depleted global resources, light-emitting diodes (LEDs) have emerged as one of the most appealing lighting systems, among which metal nanoclusters (NCs) are regarded as one of the most promising phosphors for color conversion in LEDs. However, dispersed metal NCs often exhibit drawbacks such as low emission intensity, which can be remedied by aggregation-induced emission (AIE) induced by self-assembly strategy. In this study, based on a water-soluble silver NCs (((NH₄)₉[Ag₉(mba)₉], H₂mba = 2-mercaptobenzoic acid, hereafter referred to as Ag₉ NCs) with atomically precise structure, the precipitation of yellow nanorods with strong luminescence is generated under Li⁺ coordination for the first time. Compared to Ag₉ NCs, the Ag₉ NCs/LiNO₃ composites demonstrate significantly enhanced luminescence performance, realizing an increase in quantum yield from zero to substantial levels (7.8%) and achieving a large Stokes shift of 262 nm, which is much larger than the Stokes shift of Ag₉ NCs composite materials reported in most articles (160 nm). Furthermore, the fluorescence lifetime has been extended by 254 times, from 3.2 ns to 834.7 ns, the long lifetime and large Stokes shift imply that it is phosphorescence emission. Due to its exceptionally strong photoluminescence intensity, it can be mixed with the commercial phosphor for used as a white phosphor. The study shows that the superior optical qualities of Ag₉ NCs/LiNO₃ composites are of great application value in the manufacture of white LEDs, which opens a wider range of potential uses for Ag NC in the optical device industry.