Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties

Abstract

Water soluble nanoparticles (NPs) with a high emission property were synthesized via hydrothermal routes. In this report, we chose thiol ligand N-acetyl-L-cysteine as the ideal stabilizer and have successfully employed it to synthesize readily size-controllable CdTe NPs in a reaction of only one step. Hydrothermal synthesis of CdTe NPs has been carried out in neutral or basic conditions so far. We found out that the pH value of precursor solutions plays an important role in the uniformity of the particle size. Actually, high quality CdTe NPs were synthesized under mild acidic conditions of pH 5. The resultant NPs indicated good visible light-emitting properties and stability. Further, the experimental results showed that the reaction temperature influenced significantly the growth rate and the maximum size of the NPs. The CdTe NPs with a high photoluminescence quantum yield (the highest value: 57%) and narrower half width at half maximum (the narrowest value: 33 nm) were attained in very short time, within 40 minutes, reaching diameters of 2.3 to 4.3 nm. The PL intensity was increased with an increase in the reaction time, reflecting the suppression of nonradiative recombination processes. Furthermore, the formation of CdTe/CdS core-shell structures was discussed from the viewpoint of PL dynamics and X-ray diffraction studies.

Synthesis of Water-Soluble CuInS2 Quantum Dots by a Hydrothermal Method and Their Optical Properties

“…[5][6][7][8] QDs have been extensively studied for use in various applications, including light-emitting diodes, 9 biomolecular imaging, 10 and QD solar cells. 11 To date, most studies have focused on the QDs of type II-VI semiconductors such as CdTe, CdSe, and CdS, [12][13][14][15][16] with a particular focus on CdSe QDs with uniform size and high PL QY. 12,14,15 However, these semiconductor QDs contain the toxic element Cd, and their application in consumer products is strictly regulated.…”

“…In addition to being nonvolatile and nontoxic, NAC possesses good water solubility and excellent biocompatibility. [36][37][38][39][40] To date, NAC-capped CdTe/CdS, 36,37 CdTe, 37,38 and ZnSe QDs, 39,40 have been successfully synthesized with excellent PL properties. Therefore, NAC shows great potential for use as a ligand in the synthesis of water-soluble CIS QDs.…”

Experimental verification of Förster energy transfer and quantum resonance between semiconductor quantum dots

“…Notable properties of semiconductor QDs include the ability to control the photoluminescence (PL) energy by changing the QD size and high PL efficiency [7][8][9][10][11][12].…”

“…Furthermore, the QD size could be controlled by the wavelength of the light used for irradiation during photoetching. CdS QDs with mean diameters of 4.5 and 5.0 nm were used as energy donors (D) and acceptors (A), respectively.Synthesis and optical properties of CdTe QDsCdTe QDs can be synthesized by a hydrothermal method as described in the previous paper[11,37]. Briefly, freshly prepared NaHTe solution was injected into the solutions of Cd(ClO 4 ) 2 •6H 2 O and N-acetyl-L-cysteine (NAC) at pH 7.0.…”

“…Then, 10 mL of the solution was loaded into an autoclave and incubated at 200°C for a specified period. The QD size can be controlled by the reaction time as discussed in refs [11]. and[37].…”