Regulating the near-infrared region to visible-light emission by adjusting cuprophilic interactions for blue light-excited phosphors

Luminescent copper(I)-based clusters have attracted intensive attention in solid-state lighting. However, rationally regulating the luminescence performance through accurate structural control remains a challenge. Herein, three structurally different hexanuclear copper(I) nanoclusters were designed by regulating organic ligands to disclose the structure–photoluminescence relationship. The emission bands of the copper(I) nanoclusters displayed stepwise blueshifts from the near-infrared region to visible red-light region, which could be ascribed to the cluster-centered phosphorescence emission. This is the first study to report the luminescence regulation of hexanuclear copper(I) nanoclusters by regulating cuprophilic interactions. The underlying mechanism was clearly revealed by precise structural analysis, steady-state, transient, and temperature-dependent luminescence measurements, and theoretical calculations. Importantly, Cu6(BPT)6 (BPT = 5-bromopyridine-2-thiolate, UJN-Cu4) and Cu6(TPT)6 (TPT = 5-(trifluoromethyl)pyridine-2-thiolate, UJN-Cu5) could be effectively excited by a blue light, thereby meeting the requirement for device applications that are based on a commercial 460 nm-blue light-emitting diode (LED) chip. White LEDs and flexible emissive thin films were fabricated to demonstrate the application potential of polynuclear copper(I) nanoclusters.