Synthesis and characterization of CdTe quantum dots by one-step method

Abstract

ABSTRACT. L-Cysteine (Cys)-capped CdTe quantum dots (QDs) were prepared when sodium tellurite worked as a tellurium source and sodium borohydride acted as a reductant. The influences of various experimental variables, including pH values, Cd/Te and Cd/Cys molar ratios, on the photoluminescence (PL) quantum yield (QY) of the obtained CdTe QDs have been systematically investigated. Experimental results indicated that green to red emitting CdTe QDs with maximum quantum yield of 19.4% can be prepared at pH 11.5 and n(Cd ):n(Cys) = 1:0.07:2.0. X-Ray powder diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the crystal structure and shape of CdTe QDs. The results showed that the prepared CdTe QDs were of cubic zinc blend crystal structure in a sphere-like shape.

Photoconductive Detector Based on CdTe Nanorods

“…The absorption peaks for CdTe are in the visible spectrum range and it has a wide range of absorbance for all the visible range. These results agree with reports of the references [8], [10] and [13]. The electrical properties of the prepared films were estimated from Hall measurements as follow: the average Hall coefficient, the carrier mobility and the bulk concentration of the samples (60,120,180 min) respectively as shown in table 3.…”

“…By controlling one diameter of the nanoparticle down to a few nanometers, CdTe nanoparticles offer a wide range of band gap energy in the visible spectrum [5]. So far, two successful wet chemical routes of synthesis, including organic (non-aqueous known as TOP-TOPO method) and aqueous synthesis have been developed for the preparation of Nano CdTe [3,4,8]. Aqueous synthesis is more reproducible, cheaper, less toxic, water-soluble and bio-compatible [9].The aqueous synthetic method for thiol-capped Nano CdTe have been reported recently including the hydrothermal synthesis [10], solvothermal decomposition [2] or microwave irradiation [11], in which various functional groups (e.g.…”

“…These stabilizing (capping) agents covalently binds to the surface atoms of the nanocrystallite and has the ability to control the size and shape of the growing particles through charge transfer [13], the stabilizing ligands consist of a polar anchoring group and either a polar hydrocarbon chain (synthesis in organics) or a charged group (synthesis in water to provide water solubility [14]). These ligands must dynamically adsorb on/desorb from the surface of the nanocrystals at the synthesis temperature in order to allow for growth while the nanoparticles are stabilized against aggregation [9].In most of aqueous synthesis also ours Te powder [1,4,9] or TeO 2 [8], Na 2 Te[3], Al 2 Te 3 lumps [13]is often used as tellurium sources, which needs a pretreatment to synthesize the instable tellurium precursor (NaHTe or H 2 Te) and the process of preparing Nano CdTe requires nitrogen or argon as the protective gas at the initial stage. In this work, synthesize Cysteine-CdTe nanorods by wet chemical aqueous route and characterized by UV-visible, XRD and SEM was studied, also CdTe nanorods layer was deposited on porous silicon to fabricate a visible photo detector.…”

Synthesis and characterization of oleic acid stabilized CdTe quantum dots and their properties as luminescence quencher of a pyridine pendented rod-coil homopolymer

“…The diffraction angles (2θ), 24°, 27°, 40°, and 48°can be assigned to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes, respectively, corresponding to the cubic zinc blend structure [18]. The diffraction pattern displays typical low intensity/broad peaks of a nanosized material which could be attributed to the finite crystallite size of the nanomaterials [19].…”