Preparation of uncapped CdSe1−xSx semiconducting nanocrystals by mechanical alloying

Abstract

A novel chemical synthesis method of monodispersed luminescent CdSe nanoparticles AIP Conf. Influence of particle size in hybrid solar cells composed of CdSe nanocrystals and poly(3-hexylthiophene)Composition-tunable ternary CdSe 1Àx S x nanocrystals are among the most extensively studied alloyed semiconducting quantum dots. They are, however, almost exclusively prepared by wet chemical routes which lead to surface-capped nanoparticles. Herein, we show that simple mechanical alloying can be applied to prepare uncapped CdSe 1Àx S x nanocrystals through the entire composition range. The resulting nanocrystals have average sizes smaller than 9 nm, are chemically homogenous, and show a linear lattice parameter-composition and close-to-linear band gap-composition relationships, demonstrating the ability for band gap engineering through composition tuning.

Effect of Gradient Alloying on Photoluminescence Blinking of Single CdSxSe1–x Nanocrystals

“…As depicted by the XRD patterns, the major diffraction peaks of (100), ( 002), ( 101), ( 110), (103), and (112) planes were observed, corresponding to a typical hexagonal wurtzite structure. 20,31,37,52,53 As mentioned in most of the earlier studies on alloyed CdSSe systems, 22,37,54 if the NCs were a mixture of individual CdSe and CdS domains, the XRD pattern would likely be a superposition of XRD patterns of pure bulk CdSe and CdS. Instead, we observe that the diffraction peaks of our alloyed samples lie between bulk CdSe (ICDD no.…”

Mid-IR band gap engineering of CdxPb1−xS nanocrystals by mechanochemical reaction

“…This exponential equation fits the Boltzmann function and is different from the expression of those CdSe 1−x S x nanocrystals with direct band gaps. 24 The direct band gap energy of 40h as-milled Cd x Pb 1−x S nanocrystals still keeps linear relationship with the cadmium concentration as being shown in Figure 7(a). However, it is strange that the direct gap energy of Cd x Pb 1−x S nanocrystals decreases with cadmium content, the more is the cadmium content, the smaller is the direct band gap.…”

“…They are similar to optical spectrum of bulk semiconductors and different to that of chemically alloyed semiconductor nanocrystals, these optical spectra are in accordance with that being reported in literatures and our previous work. 21,24 In our previous work, we were able to continuously tune the band gap energies of CdSe 1−x S x nanocrystals from 560 nm to 815 nm, 24 that of CdTe 1−x S x nanocrystals from 815 nm to 1400 nm. 28 Nowadays, we are able to tune band gap energies of Cd 1−x Pb x S nanocrystals from 1240 nm to 2638 nm, which extends the optical absorption band edges or band gap energies beyond mid-IR region (2638 nm).…”

“…Mechanical alloying process is such a physical method for mass fabrication of surface clean semiconductor NCs. A certain number of semiconductor nanocrystals, such as PbS, 19 CdSe, 20 CdTe, 21 CdS, 22 ZnS, 23 and CdSe 1−x S x (x = 0∼1), 24 have been prepared by this top-down approach with average sizes smaller than 10 nm. In this work, we are going to present the synthesis of ternary Cd x Pb 1−x S NCs with clean surface and homogeneous composition by mechanical alloying process.…”

Effect of Se concentration on mixed phonon modes and spin orbit splitting in thermally evaporated CdSxSe1−x (0 ≤ x ≤ 1) films using CdS–CdSe nano-composites

“…Several low cost techniques such as chemical bath deposition [8], spray pyrolysis [9], physical thermal evaporation [10], solvothermal [11,12], hydrothermal [13], etc., have been successfully used to synthesize these binary compounds in the form of thin films as well as nanostructures. Alloying of these two binary compounds to form new ternary CdS x Se 1Àx (0 x 1) alloys has also been contemplated and achieved through several techniques such as laser ablation [14], mechanical alloying [15], chemical bath deposition [16], etc. The structural and optical properties of the resulting CdS x Se 1Àx (0 x 1) material lie between the respective properties of the end binary compounds.…”