Light-Induced Inhibition of Photoluminescence Emission of Core/Shell Semiconductor Nanorods and Its Application for Optical Data Storage

Abstract

In this work, we demonstrate that the photoluminescence emission of CdSe/CdS spherical core/rod like shell nanorods can be completely inhibited by using low-energy femtosecond laser pulses at 720 nm. A combined analysis of optical confocal microscopy images and transmission electron microscope micrographs reveals the presence of different power regimes in the nanocrystals photodegradation process. The photoluminescence inhibition of the nanorods is found to start at a power range in which no apparent structural damage occurs to the nanorods after irradiation. This suggests the presence of a photochemical transformation of the nanocrystals that is of potential interest for application in optical data storage. This is because in recording systems based on photochemical processes the photoexcited volume can be effectively confined within the diffraction-limited laser focus. We indeed demonstrate that the recorded mark can be scaled down to a few nanorods, or even to a single nanorod, without crosstalk between adjacent nanostructures separated by the optical resolution of the instrument used. Finally, the intensities required for inhibiting the emission of nanorods and for avoiding any peripheral thermal damage of the hosting polymer matrix are determined (200−360 GW/cm 2 ), and the mechanism underlying the photochemical process is discussed.

Morphological and chemical transformations of single silica-coated CdSe/CdS nanorods upon fs-laser excitation

“…30 The deformation of uncoated CdSe/CdS NRs to a spherical shape under fs-pulse excitation was observed previously. 35 However, from these experiments it was not clear whether these were remnants of sublimated NRs and/or really deformed fragments of the original NRs.…”

“…where the inhibition of luminescence is desired, the amount of absorbed pulses played a role as well. 35 Thus, heat accumulation is an important factor for the photostability of CdSe/CdS NRs for high repetition rate lasers.…”

High-security-level multi-dimensional optical storage medium: nanostructured glass embedded with LiGa5O8: Mn2+ with photostimulated luminescence

“…A prerequisite for these advanced technologies is to be capable of sophisticated manipulation of light-matter interactions at the nanoscale 2 . To date, several kinds of nanomaterials, such as metallic nanocrystals (NCs) 8,11 , graphene oxide [12][13][14] , semiconductor quantum dots [15][16][17] and rare-earth ion-doped NCs 18,19 , have been developed as ODS media, utilizing their physical and/ or chemical state variations during light-matter interactions. Despite the fascinating ODS properties, the shortcomings of high cost, tedious preparation route and low production greatly hinder their practical applications; moreover, these NCs are bound to disperse into organic hosts, which brings about a stability issue: colouration-or shrinkage-induced performance reduction under long-term repeatable laser write-in/read-out 9,[20][21][22] .…”

Two-Photon-Induced Blue Shift of Core and Shell Optical Transitions in Colloidal CdSe/CdS Quasi-Type II Quantum Rods

“…Consequently, several studies have proposed them as suitable candidates for two-photon-pumped biolabels 14 or as active materials in lasing 15À17 and optical data storage. 18,19 Experimental and theoretical studies that focused on an improved fundamental understanding of 2PA in colloidal nanocrystals have revealed that in the limit of strong confinement, for instance experienced by small PbS and PbSe nanocrystals, quantum confinement may also weaken the optical selection rules, giving rise to one-photonallowed transitions in 2PA spectra and vice versa. 20,21 Surprisingly, two-photon-induced photoluminescence excitation (2PPLE) spectra for cadmium chalcogenides have been less investigated.…”

“…More specifically, Qrods can exhibit a large two-photon absorption (2PA) cross section, , and the concomitant efficient sub-band-gap excitation of the photoluminescence is of great interest for applications in photonic and optoelectronic devices. Consequently, several studies have proposed them as suitable candidates for two-photon-pumped biolabels or as active materials in lasing − and optical data storage. , …”