Impact of the Plasmonic Metal Oxide-Induced Photocatalytic Processes on the Interaction of Quantum Dots with Metallic Nanoparticles

Abstract

We study plasmonic control of photocatalytic properties of metal oxides and the ways they influence interaction of quantum dots with metallic nanostructures. For this, gold nanostructures are coated with ultrathin layers of metal oxides (Al, Cu, Cr, or Ti oxide) and then covered with CdSe/ZnS quantum dots. The results show how the photocatalytic properties of such metal oxides are renormalized by plasmon near fields. In the cases of Al, Cr, and Ti oxides, the results mostly indicate the direct impact of plasmon fields via enhancement of optical excitations of the quantum dots. For the case of Cu oxide, however, the outcomes are found to be quite unique. In the absence of the plasmonic structures, such an oxide (CuO) presents highly active photocatalytic processes, leading to complete annihilation of the quantum dot emission. In the presence of the metallic nanostructures, the emission of such quantum dots is revived, offering an ultrafast decay process (∼112 ps). These results indicate that in the case of CuO, the plasmonic metal oxide-induced photocatalytic processes include not only direct impact of plasmon near fields on the optical excitations of quantum dots but also the enhancement of interband transitions in CuO nanoparticles. The effects of energy transfer from quantum dots to metallic nanostructures and its equalization with Purcell effects on such processes are discussed.

Localized Surface Plasmon Resonance Enhanced Light Absorption in AuCu/CsPbCl3 Core/Shell Nanocrystals

“…Note that the PL enhancement presented in Figure 3b is, in general, the result of competition of two processes, i.e., Purcell effect and energy transfer from the PNC shell to the AuCu metallic core. [44][45][46][47] While the Purcell effect, i.e., ratio spontaneous emission rate in the presence of the plasmonic effects to that in the absence of these effects, enhances the PL, the energy transfer process tends to reduce the emission of PNC. [44] The fact we see PL emission enhancement in Figure 3b suggests that the contribution of the Purcell effect is more dominant.…”

Probing How Various Metal Ions Interact with the Surface of QDs: Implication of the Interaction Event on the Photophysics of QDs

“…As already discussed, ZAIS QDs are less toxic in nature and they also possess different characteristic photophysical properties such as (a) a long tail of absorption in the longer wavelength region, (b) broad emission spectra whose full width at half-maximum (fwhm) is greater than 100 nm, (c) large stoke shifts, and (d) long fluorescence lifetime . However, the broad nature of the emission of ZAIS QDs also indicates the presence of defects within the QDs. , If these defects associated with the QDs are reduced/removed, − then ZAIS QDs are expected to be more interesting in terms of various applications. − We note here that the properties of these QDs can easily be altered by suitable surface ligands which are used for capping the surface of the QDs to stabilize the system. , It is well-known that the surface/interface of colloidal QDs, which are usually formed by organic ligands during the synthetic procedure of chalcogenide QDs, plays an important role in tuning their optical properties. , The surface functionalization of QDs through a chemical process is found to be a very useful approach to bring change in the energies and the spatial distribution of the QDs involving the core as well as surface states . This has been observed due to the fact that surface ligands can control (a) the extent of enrichment of cations and anions on the surface, (b) degree of association of surface ions with the core, (c) the crystal structure and size of QDs when the ligands act as surfactants, and (d) confinement energy of charge carriers .…”

Modified Absorption and Emission Properties Leading to Intriguing Applications in Plasmonic–Excitonic Nanostructures

“…The plasmonic properties of Au nanostructures on various metal oxide surfaces covered with CdSe/ZnS QDs has been studied and PL response is shown in Figure 15g. [ 301 ] The PL intensity decreased with introduction of Au NISs on SiO 2 surface which is in contrast from other metal oxide surfaces (Al, Ti, Cr, and Cu oxide). From Figure 15g, it can be noticed that Al and Ti oxide surface provide greater enhancement instead of Cr oxide surface when Au NISs are introduced over QDs.…”

“…e) Reproduced with permission. [ 301 ] Copyright 2020, ACS Publications. f) Reproduced with permission.…”

“…Moreover, the carrier lifetime reduces further with introduction of Au NISs on these surfaces. [ 301 ] The QDs deposited on glass have lifetime of 2.25 ns which gets drastically reduced to value of 0.112 ns on Au/CuO surface lined with 1 nm of SiO 2 .…”