Room-temperature formation of CdS magic-size clusters in aqueous solutions assisted by primary amines

Abstract

Aqueous-phase approaches to semiconductor CdS magic-size clusters (MSCs) and the formation pathway have remained relatively unexplored. Here, we report the demonstration of an aqueous-phase, room-temperature approach to CdS MSCs, together with an exploration of their evolution pathway. The resulting CdS MSCs display a sharp optical absorption peak at about 360 nm and are labeled MSC-360. With CdCl 2 and thiourea as the respective Cd and S sources, and 3-mercarpotopropionic acid as the ligand, CdS MSC-360 develops in a mixture of a primary amine and water. We argue that the primary amine facilitates roomtemperature decomposition of thiourea when CdCl 2 is present, and the formation pathway of MSCs is similar to that in organic-phase approaches. Our findings show there is a viable avenue to room-temperature aqueous-phase formation of CdS MSCs. Providing explanations of the procedure developed including the formation of large aggregates, the present study represents an important advance towards a mechanistic understanding of nanocrystal synthesis.

Synergetic effect of the surface ligand and SiO2 driven photoluminescence stabilization of the CH3NH3PbBr3 perovskite magic-sized clusters

“…While the CH 3 NH 3 PbBr 3 PMSCs size reported on the other previous reports commonly shows a slightly larger diameter size (5.0 ± 0.9 nm) than the estimated value that was calculated from Bruss model (around 2–4 nm) due to the aggregation induced by the electron microscopy preparations that could not be avoided 10 . Despite the shortcomings of the TEM measurement tools with regards to providing the precise structural and information of the Semiconductor Magic-sized Clusters 8 , 35 – 37 and the possibility aggregation of the sample during microscopy measurement, these as-synthesized PMSCs are in PMSCs range size with slightly smaller than other reports. Furthermore, the chemical composition of the PMSCs samples were characterized by Energy Dispersive X-ray Spectroscopy (EDS).…”

Transformation Pathway from CdSe Magic‐Size Clusters with Absorption Doublets at 373/393 nm to Clusters at 434/460 nm

“…While MSCs exhibit characteristic optical absorption at specific wavelengths, their counterpart PCs do not absorb at these or longer wavelengths [1–17] . Here the MSCs and their PCs exist as quasi isomers, which can reversibly interchange via intramolecular reorganization.…”

“…It has been shown that magic‐size clusters (MSCs) have their own unique precursor compounds (PCs) [1, 2] . This concept has recently been demonstrated in the synthesis of various II‐VI metal chalcogenide (ME) MSCs, which include CdS, [3–7] CdSe, [8, 16] CdTe, [9–12, 17] CdTeSe, [13, 14] and ZnSe [15] . In all these cases binary PCs start to form before conventional binary ME quantum dots (QDs) nucleate and grow.…”

“…In addition to the MSCs that display sharp optical absorption singlets, [3–15, 18–26] there is another type of nanospecies that exhibits sharp optical absorption doublets [16, 17, 27–44] . An example semiconductor is photoluminescent (PL) CdSe peaking at around 373/393 (Species‐393) or 433/460 nm (Species‐460) [16, 27–30] .…”

Sn-doped CdS: A New Intermediate Band Material for Solar Cells

“…On the one hand, semiconductor optoelectronic technology can utilize solar energy to produce electric energy [1][2][3][4][5], such as obtaining current through photovoltaic materials [6], producing uorescence and phosphorescence by photoluminescent materials [7,8]; on the other hand, photovoltaic technology can replace various toxic and harmful chemical fossil energy to purify the environment [9][10][11]. CdS is a direct band gap semiconductor [12][13][14][15], which has excellent photoelectric performance, such as high photoelectric conversion e ciency, low cost, long service life, rich lightemitting color and so on [16][17][18]. However, due to its large band gap (2.42 ev) [19], CdS can only absorb a little energy from the visible light and can not make full use of the visible light.…”