Lattice Strain Controls the Carrier Relaxation Dynamics in Cd_xZn_1–xS Alloy Quantum Dots

Abstract

Here, we demonstrate the impact of lattice strain on the carrier relaxation of Cd x Zn 1−x S alloy nanocrystals. In alloy nanocrystals, the difference in the lattice constants of their constituents can induce a lattice strain that varies with the composition of alloy. We have analyzed the decay curves using a multiexponential decay function, and it is found that the average lifetime decreases with increasing the concentration of Zn in Cd x Zn 1−x S alloy nanocrystals. A stochastic model of carrier relaxation dynamics of Cd x Zn 1−x S alloy nanocrystals has been proposed to estimate the values of the radiative relaxation rate, nonradiative relaxation rate, and number of trap states. Results show that the radiative and nonradiative relaxation rates and the number of trap states increase with increasing the lattice strain of the alloy nanocrystals. Such alloy nanocrystals should have great potentials for nonlinear optical properties, photovoltaic devices, and solar cell.

Radiative and Nonradiative Lifetime Engineering of Quantum Dots in Multiple Solvents by Surface Atom Stoichiometry and Ligands

“…The average fluorescence lifetime values are plotted in figure 5 (b), and shows a dependence that does not directly correlate with the QY dependence, highlighting the fact that both the average radiative and average non-radiative rates are changing. These two rates (plotted as lifetimes) are calculated as follows: 33,34 $${\tau }_r=\frac{1}{k_r}=\frac{{\tau }_{fl}}{QY}$$ and $$k_{nr}=\frac{1}{{\tau }_{nr}}=\frac{1}{{\tau }_{fl}}-\frac{1}{{\tau }_r}$$…”

Model‐Free Estimation of Energy‐Transfer Timescales in a Closely Emitting CdSe/ZnS Quantum Dot and Rhodamine 6G FRET Couple

“…Knowledge of photophysical processes taking place within semiconductor materials is important for developing next‐generation nanomaterial‐based assays with enormous possibilities in various applications . Among all photophysical processes studied in quantum dots (QDs), photoinduced electron transfer (PET) and Förster resonance energy transfer (FRET) have attracted intense interest from researchers . Recent developments of various FRET assays demonstrate tremendous applications of FRET mostly in biology, for example, as a spectroscopic ruler, in the development of biosensors, in vitro pH sensing, multiphoton cell imaging, determination of metabolic rates, and studying lipid rafts in cell membranes .…”

Facile Synthesis of Zn0.5Cd0.5S Ultrathin Nanorods on Reduced Graphene Oxide for Enhanced Photocatalytic Hydrogen Evolution under Visible Light

“…Many strategies have been developed for obtaining high-quality Zn x Cd 1-x S solid solutions and their photocatalytic performance has been investigated as well. [16][17][18][19][20][21][22][23] For example, Zhong et al synthesized wurtzite Zn x Cd 1Àx S nanocrystals with narrow room-temperature emission spectral width by using CdO-and ZnO-oleic acid complexes and sulfur as the precursors and reacting them at high temperature (310 8C). [16] Li et al synthesized Zn x Cd 1Àx S nanocrystals by thermolyzing a mixture of cadmium ethylxanthate and zinc ethylxanthate at lower temperatures (180-210 8C).…”