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Mao et al. Chem Synth 2023;3:26 https://dx.doi.org/10.20517/cs.2022.41 Page 3 of 33

Figure 1. Crystal structure model of the Chalcocite, Djurleite, Roxbyite, Digenite, Anilite, and Covellite. Sulfur and Copper atoms are
marked in yellow and blue, respectively.

digenite (Cu S), anilite (Cu S), and covellite (CuS), as shown in Table 1. Additionally, the similar
1.75
1.8
chemical properties of anion elements result in a wide range of materials for Cu E (x = 0~1, E = S, Se, or
2-x
Te). The structural and compositional diversity of copper chalcogenides creates challenges for precisely
controlled synthesis and enriches the fabrication method used.
The classical method for forming the NCs involves the “bottom-up” and “top-down” strategies. As for the
colloidal copper chalcogenides, we usually use the organic synthesis method, which includes the “hot-
injection” and “heat-up” technologies [60,61] . The process involved first preparing the copper compounds as a
precursor. Then, the flask containing the organic solvent was heated to a high temperature, and the
precursor was quickly injected. The primary stage after the injection is the boom of the nucleation. The
reaction then proceeds quickly into the crystallization and growth stage. Over time, the Ostwald ripening
occurs . Therefore, achieving desirable colloidal nanocrystals requires precise control of activity and
[62]
amount of the precursor, organic solvent, reaction temperature, and time. Omitting any of these factors
could affect the outcome. The traditional Cd- or Pb-based colloidal semiconductor has been well-studied
and applied in various ways. However, the synthesis technologies for copper chalcogenides have not yet
reached the same level as those for the Cd- or Pb-based protocols. As a result, numerous research work for
the irregular shape of copper chalcogenides is fabricated with the cation exchange method. However, it is
worth noting that the precisely controlled synthesis strategy for copper chalcogenides remains challenging
and has significant room for development.

THEORETICALLY STUDIES FOR DOPING CU-CHALCOGENIDES NCS
LSPR feature was first observed in the “Lycurgus Cup”, which was made of colloidal gold particles for
drinking. To date, the LSPR properties of the colloidal NCs have been widely used in diverse applications,
including biosensing, luminescence, and therapy.