Environmental Effects on Photoluminescence of Highly Luminescent CdSe and CdSe/ZnS Core/Shell Nanocrystals in Polymer Thin Films

Abstract

We report our systematic studies of the environmental effects on the photoluminescence (PL) from colloidal CdSe nanocrystals (NCs) embedded in polymer thin films. The highly luminescent bare-core CdSe NCs were significantly more robust than the core/shell CdSe/ZnS NCs against photoannealing under inert environments, while the core/shell NCs are more resistant to photooxidation. For the case of bare-core NCs, we show the importance of the initial photoactivation as the proper treatment for subsequent studies, a step that is basically irrelevant in the case of core/shell NCs. By measuring the PL wavelength shift, PL line width, and PL intensity, we investigated the dynamic changes of the emission properties of these NCs under different environments, including argon, oxygen, air, water vapor, and wet oxygen, and under different excitation conductions to reveal the photoinduced nature of the interactions between the nanocrystal surface and the environment. Mechanisms related to photoactivation, photooxidation, and PL enhancement are briefly discussed.

Chemical Sensitivity of Luminescent Epitaxial Surface InP Quantum Dots

“…The suited PL properties include broad absorption band, size tuneable spectral emission, higher photostability, and emission lifetime ranging between several hundreds of picosecond and tens of nanosecond [6]. In the last ten years, authors reported the sensitivity of colloidal QDs embedded into polymeric matrix [7][8][9][10][11], sol-gel materials [12,13] or dispersed in Al 2 O 3 nanopore array [13]. Per se they display sensitivity towards some commonly used solvents like methanol, ethanol, acetone and chloroform [12].…”

Quantum Dot Blueing and Blinking Enables Fluorescence Nanoscopy

“…28 While higher laser intensities accelerate the process of blueing, 32 slow spectral blue shifts have also been observed under low-level illumination from a Xe arc lamp (≈3 W cm -2 ). 26 From our analysis of approximately 200 measured fluorescence time traces of individual photooxidized quantum dots, we deduced that the duration of the off periods remains unaffected by the blueing process ( Figure 3).…”

Fluorescence Determination of Glutathione Using Tissue Paper-derived Carbon Dots as Fluorophores

“…Accordingly, the fluorescence intensity of QDs may increase in the presence of a Lewis base and a decrease in the presence of a Lewis acid. [34][35][36] The observed quenching of fluorescence intensity of EDA-CDs in the presence of GSH may be due to the Lewis acid nature of the thiol group in GSH. The hydrophilic thiols decrease the fluorescence intensity by replacing the amine species from the surface of the QDs.…”