In₂S₃ Nanocolloids with Excitonic Emission:  In₂S₃ vs CdS Comparative Study of Optical and Structural Characteristics

Abstract

Stable aqueous colloids of 2-3 nm In 2 S 3 nanocrystals have been prepared by using the classical method of nanoparticle stabilization by low molecular weight thiols. TEM crystal lattice spacing, X-ray diffraction, EDAX data, and electron diffraction indicate that the nanoparticles are predominantly in -In 2 S 3 form. They exhibit relatively strong excitonic emission at 360-380 nm with a quantum yield of 1.5%. The excitonic radiative lifetime is 350 ns, which indicates that a direct allowed electronic transition is responsible for this emission. The NMR lines of the stabilizer are strongly broadened and shifted as a result of deshielding induced by electron withdrawing by positively charged metal ions. This effect quickly wears off as the carbon chain becomes longer and the separation between the hydrogen atoms of the stabilizer and the semiconductor surface increases. The broadening is attributed to the reduced mobility of the stabilizer in the nanoparticle shell. For CdS nanoparticles of the same size, this effect was found to be substantially stronger than for In 2 S 3 . The lower density of metal centers in In 2 S 3 than in CdS, which serve as anchor points for the stabilizer, promotes greater mobility of the stabilizer moieties.

Synthesis, Optical Properties, and Self‐Assembly of Ultrathin Hexagonal In2S3 Nanoplates

“…In addition, the UV/Vis spectra of nanoplates showed a steplike shape, which was mentioned to be an indicator of conduction and valence band transition in b-In 2 S 3 . [20] Interestingly, we observed no significant differences between the UV/Vis spectra of 63-, 45-, 33-, and 22-nm nanoplates (see Supporting Information for UV/ Vis spectra of 63-, 45-, and 22-nm nanoplates), which implies that the sizes (22-63 nm) of the nanoplates are beyond the quantum confinement range. Detailed optical characterizations including emission, quantum yields, and decay kinetics will be reported elsewhere.…”

“…Figure 3 b shows a representative UV/Vis absorption spectrum of 45-nm hexagonal nanoplates. Compared to the absorption peak of 3.0-nm nanoparticles, [20] that of 45-nm nanoplates was red-shifted by 30 nm. In addition, the UV/Vis spectra of nanoplates showed a steplike shape, which was mentioned to be an indicator of conduction and valence band transition in b-In 2 S 3 .…”

“…Recently, 3-nm b-In 2 S 3 nanocrystals were prepared by an arrested-precipitation method using aqueous InCl 3 solution and a thiol stabilizer. [20] However, as far as we are aware, the synthesis of b-In 2 S 3 in organic media has received little attention, although it is well recognized that various organic surfactants can be excellent reaction media for synthesis of high-quality nanocrystals. [21] Herein we report on the synthesis of monodisperse hexagonal b-In 2 S 3 nanoplates of 0.76-nm thickness in organic media at high temperature by using the arrested-precipitation method.…”

Enzymatic biomineralization of biocompatible CuInS2, (CuInZn)S2and CuInS2/ZnS core/shell nanocrystals for bioimaging

“…34,35 These latter materials will directly form a metal sulfide solid upon reaction with the reactive sulfur, likely H2S, formed by the enzymatic turnover of L-cysteine by the putative cystathio-nine γ-lyase class CSE enzyme. 28 In contrast, reaction with indium nitrate forms a relatively stable species with a charac-teristic absorption peak at 290 nm, which has previously been identified as a molecular cluster of indium and sulfur, 46 rather than bulk or nanocrystalline In2S3. A similar result is obtained upon addition of Na2S to a mixture of indium nitrate with L-cysteine, whereas a bulk precipitate of In2S3 likely combined with indium hydroxide is formed in the absence of L-cysteine.…”

A Novel in Situ Oxidization–Sulfidation Growth Route via self-Purification Process to β-In2S3 Dendrites

“…It is reported that its intensity and position with respect to the main peak is affected by the choice of stabilizer and by the media (37). The closeness of the emission peaks to the absorption onset of the semiconductor indicates that this emission comes from the interband electron-hole recombination.…”