Tunable Visible Emission of Ag-Doped CdZnS Alloy Quantum Dots

Abstract

Highly luminescent Ag-ion-doped Cd1−xZnxS (0 ≤ x ≤ 1) alloy nanocrystals were successfully synthesized by a novel wet chemical precipitation method. Influence of dopant concentration and the Zn/Cd stoichiometric variations in doped alloy nanocrystals have been investigated. The samples were characterized by X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM) to investigate the size and structure of the as prepared nanocrystals. A shift in LO phonon modes from micro-Raman investigations and the elemental analysis from the energy dispersive X-ray analysis (EDAX) confirms the stoichiometry of the final product. The average crystallite size was found increasing from 1.0 to 1.4 nm with gradual increase in Ag doping. It was observed that photoluminescence (PL) intensity corresponding to Ag impurity (570 nm), relative to the other two bands 480 and 520 nm that originates due to native defects, enhanced and showed slight red shift with increasing silver doping. In addition, decrease in the band gap energy of the doped nanocrystals indicates that the introduction of dopant ion in the host material influence the particle size of the nanocrystals. The composition dependent bandgap engineering in CdZnS:Ag was achieved to attain the deliberate color tunability and demonstrated successfully, which are potentially important for white light generation.

Structural characterization and photoluminescence properties of pure and Ag(1–5%)-doped (Cd0.95Zn0.5)S phosphors synthesized by solid-state reaction methods

“…Moreover, these semiconductor materials are of great interest for both fundamental research and industrial development. Because of their nonlinear optical properties, electrical properties, tremendous luminescence quality, quantum cutting and other excellent physical and chemical properties, group II-VI microcrystalline semiconductors have potential applications as sensors, conductors, diodes and optical devices [1][2][3][4]. For numerous applications in the field of optics, the optical properties of materials are required to be tunable and thus controllable.…”

Electronic and optical properties of CdS/CdZnS nanocrystals

“…The band gap of ZnCdS can be tuned, depending on the alteration of the content of its constituent. [10] ZnCdS is widely used as a wide-band-gap window material in heterojunction solar cells, [11] low-voltage cathode luminescence, [8] high-density optical recording, and blue and ultraviolet laser diodes. [12] II-VI compound semiconducting nanocrystals have attracted much attention, owing to their unique optical properties that can be tuned not only by changing the particle size but also by changing the composition of the alloy.…”

Annealing-induced effects on structural and optical properties of Cd1−xZnxS thin films for optoelectronic applications

“…These peaks are shifted towards higher Raman shift side in comparison to the 1-LO phonon peak of CdS (∼297 cm −1 ) [28][29][30]. A prominent 1-LO phonon mode and a 2-LO second harmonic phonon mode of comparatively less intensity were found for all the compositions and at all temperatures except for the sample with x = 0.8.…”