Time resolved and temperature dependence of the radiative properties of thiol-capped CdS nanoparticles films

Abstract

In this work, we present the temperature-dependence and time-resolved photoluminescence (PL) of CdS nanoparticles capped independently with three different ligands thiophenol, thioglycerol, and l-cysteine over a broad temperature range from 10 to 300 K. The respective nanoparticles sizes in the three systems studied in this work are 1.5, 4, and 2 nm as determined from X-ray diffraction (XRD). From the analysis of AFM images, it was found that the lateral particle sizes of capped CdS nanoparticles are greater than those deduced from XRD or optical absorption measurements. The aim of this study is the investigation of the impact of the organic ligands on the radiative recombination dynamics in organically capped CdS nanoparticles. From the PL study and based on the temperature-dependence and time-resolved emission spectroscopy, we conclude that the emission of CdS QDs film originates from recombination of the delocalized carriers in the internal core states with a small contribution of the localized carriers at the interface. The PL decay reveals a biexponential behavior for the entire three samples at all temperatures. One of the two exponential components decays rapidly with a time τ1 in the range 0.5–0.8 ns, whereas the other decays much more slowly, with a time τ2 in the range 1–3 ns. The weak activation energy (32–37 meV) deduced from the temperature dependence of the PL intensity suggests the involvement of shallow traps. The analysis of the experimental results reveals a relatively narrow size distribution, an efficient surface passivation, and a satisfactory thermal stability of CdS nanocrystals.

Shortwave infrared luminescent Pt-nanowires: a mechanistic study of emission in solution and in the solid state

“…Lower temperatures tend to localize such motion to a smaller distance. Similar blue-shift behavior was reported for a series of In-As quantum dots 76 and wells 72 and Cd-halcogenide 77, 78 where even values of the PL temperature shifts were reported to be in the same range of 30–60 meV.…”

Aqueous synthesis of functionalized copper sulfide quantum dots as near-infrared luminescent probes for detection of Hg2+, Ag+ and Au3+

“…Temperature effect competition between radiative and nonradiative transitions have been found by Mohamed and Pendyala et al . 31 , 32 . Figure 7(b) shows the variation of the Cu 2 S QDs size and size distribution with the temperature.…”

Thioglycerol-functionalized CdSe quantum dots detecting cadmium ions

“…We have followed the method previously described for the synthesis of CdS (cadmium sulfure) QDs capped with thiol derivatives [25] with some modifications. The chemicals were purchased from Sigma, Aldrich and Fluka.…”