Chromium-oxide enhancement of photo-oxidation of CdSe/ZnS quantum dot solids

Abstract

Published by the American Institute of Physics. Related ArticlesEffect of dimensionality and morphology on polarized photoluminescence in quantum dot-chain structures J. Appl. Phys. 112, 084314 (2012) Quasiresonant excitation of InP/InGaP quantum dots using second harmonic generated in a photonic crystal cavity Appl. Phys. Lett. 101, 161116 (2012) Size-dependent radiative decay processes in graphene quantum dots Appl. Phys. Lett. 101, 163103 (2012) Optical absorbance of doped Si quantum dots calculated by time-dependent density functional theory with partial electronic self-interaction corrections J. Chem. Phys. 137, 144301 (2012) Analysis of the modified optical properties and band structure of GaAs1−xSbx-capped InAs/GaAs quantum dotsIn this paper, we report the results of depositing CdSe/ZnS quantum dots (QDs) on Cr coated substrates. Compared to such QDs on glass surfaces, the emission peak blueshifts and broadens much more rapidly. The acceleration of the process is presented by showing the relative intensity, position, and full-width as a function of time for various laser intensities, and the effects on photoinduced fluorescence enhancement and photo-oxidiation are discussed. We also consider the thickness of the Cr layer and photo-induced heating, showing this factor should instead lead to a redshift of the peak. Oxidation of colloidal QDs is known to cause blueshifts and broadening of emission peaks (photobleaching). We attribute the faster photobleaching of QDs on Cr films to enhancement in the oxidation of the ZnS shell by catalytic or direct chemical reactions with chromium oxides. As a working hypothesis, this leads to additional paths for breakdown of the otherwise protective nature of the shell. V C 2012 American Institute of Physics. [http://dx.

Probing the structural dependency of photoinduced properties of colloidal quantum dots using metal-oxide photo-active substrates

“…12,13 Recently, we have shown that nano-scale-thin layers of metal oxides can have significant impact on the photo-induced properties of colloidal QDs. 14,15 Our results demonstrated that, depending on the types of these oxides and the basesubstrates on which they were deposited, such oxides could promote unique sets of photo-induced processes in such QDs.…”

“…14 On the other hand, when 1 nm of Cr oxide is deposited on a borosilicate glass base-substrate, it can profoundly accelerate the rate of photo-oxidation of the QDs. 15 We have also shown that when metallic nanoparticles are coated with an ultrathin layer of Cr oxide, the plasmonic enhancement of the energy transfer between CdSe/ZnS QDs can be suppressed with irradiation. 16 These prior results suggest that when a substrate is coated with an ultrathin layer of a specific metal oxide, it can be used as a photo-active substrate to study some of the characteristic features of QDs using the unique photocatalytic effects of the oxide.…”

Plasmonic Hot‐Electron‐Induced Control of Emission Intensity and Dynamics of Visible and Infrared Semiconductor Quantum Dots

“…[ 31 ] This can change the exciton transition energies and increase of their nonradiative decay rates. [ 6,7,32 ] Figure shows the evolution of the emission spectra of the PbS QDs on a glass substrate covered with Si after they were irradiated with the 514 nm laser for a given period of time (legends in seconds). The laser power was 2 mW power, and the maximum irradiation time was 300 s. The results show blueshift of the emission spectra as the irradiation time was increased.…”

“…These are indications of oxidation and formation of defect sites. [ 31,32 ] Considering these issues, the measurements presented in this paper were taken within a few seconds of exposure to the laser beam and immediately after preparation of samples. As for the case of TCSPC, we reduced the average laser intensity to less than 0.03 mW.…”

Improvement of plasmonic enhancement of quantum dot emission via an intermediate silicon-aluminum oxide interface

“…For example, the Cr oxide can induce strong photooxidation of QDs and suppression of PFE. 13 When MNPs are coated with a ultrathin layer of Cr oxide and irradiated, this accelerated photo-oxidation can even supress plasmonic enhancement of F€ orster resonance energy transfer (FRET) between QDs. 14 In this paper, we investigated the emission of QDs when they were deposited on plasmon-metal oxide substrates.…”