Reversible self-assembly of MxS (M = Cu, Ag) nanocrystals through ligand exchange

A facile ligand exchange operation is found to be effective for the assembly and disassembly of MxS (M = Cu, Ag) nanocrystals in solution. The Cu1.94S nanoplates are taken as an example for tuning the physical properties of the nanocrystal colloid through reversible self-assembly. By establishing and disintegrating self-assembly of the Cu1.94S nanoplates, the localized surface plasmon resonance wavelength of the colloid can be switched between 1600 nm and 1850 nm, while the optical band gap can be tuned between 1.6 eV and 2.1 eV. The reported result is of significance for the potential applications of nanocrystals in fields such as photovoltaics and photodetection.