Role of dopant concentration and surface coating on photophysical properties of CdS: Eu3+ nanocrystals

Abstract

Here, we report the role of dopant concentration and surface coating of CdS: Eu3+ nanocrystals on the modification of crystal structure and their photoluminescence properties by steady-state and time resolved fluorescence studies. It is found that photoluminescence properties are sensitive to the crystal structure which is controlled by surface coating and dopant concentration. The emission intensity of the peak at 614 nm (5D0 --> 7F2) of the Eu3+-ions is found to be sensitive to the doping and surface coating of CdS nanocrystals. It is found that the average decay times tau are 248, 353 and 499 micros for 0.25, 0.5 and 1.0 mol% Eu ions doped into CdS nanocrystals, respectively. From the decay time measurements, it is evident that the energy transfer occurs from CdS nanoparticles to Eu3+ ions and the calculated energy transfer efficiency from CdS nanoparticles to Eu3+ ions is 9.2 and 35% for Eu3+ ions coated and doped CdS nanoparticles, respectively. Our analysis suggests that site symmetry of ions plays a very important role in the modifications of radiative and nonradiative relaxation mechanisms.

Understanding the role of particle size on photophysical properties of CdS:Eu3+ nanocrystals

“…Recently, Erwin et al [2] described the inclusion of TM ions in semiconducting nanocrystals and described the important roles of crystal structure and shape of the nanocrystals in optimizing the efficiency of TM-doped nanocrystals. A number of papers published on the luminescence of nanocrystalline II-VI semiconductors doped with TM/RE ions [1][2][3][4][5][6][7][8][9][10]. However, there has been a controversy over the decay kinetics of the Mn 2+ impurity luminescence.…”

“…Doping the semiconductor nanocrystals with transition metal (TM) and rare-earth (RE) ions has been the subject of research in recent years to find out the potential applications in photonic and biophotonic field [1][2][3][4][5][6][7][8]. The optical properties of TM ion-doped semiconductor nanoparticles have been extensively investigated since 1994.…”

Synthesis and time-resolved photoluminescence spectroscopy of capped CdS nanocrystals

“…Due to high surface area of nanoparticles, surface defects play an important role in their quantum efficiency. The tunability of the properties of nanoparticles by controlling their size and shape may provide an advantage in formulating new composite materials with optimized properties for various applications [4][5][6][7][8][9][10]. To date, there has been much progress in the fabrication of quantum dots for devices but the relaxation dynamics of the electronic states in quantum dots remain an open fundamental debate.…”

Synthesis and spectroscopic study of high quality alloy Cd x Zn1−x S nanocrystals

“…[1][2][3][4][5][6][7][8][9] The size dependence of the band gap is the most identified aspect of quantum confinement in semiconductors; the band gap increases as the size of the particles decreases. In alloy nanocrystals, the colour-tuning emission properties are controlled by changing their constituent stoichiometry without changing the particle size.…”