Charge transfer dynamics of the CdTe quantum dots fluorescence quenching induced by ferrous (II) ions

Abstract

Size dependence of glutathione capped CdTe quantum dots (GSH-CdTe QDs) on the sensitivity and selectivity in the fluorometric detection of ferrous (II) ions (Fe2+) has been systematically investigated. Smaller-size QDs show higher sensitivity in the detection of Fe2+, resulting in higher quenching efficiency and red shift of the fluorescence peak of QDs. Stern–Volmer plots indicate that the charge transfer model can be employed to account for the observed fluorescence quenching effect. Fe2+ is bound to the surface of QDs by GSH and excited electrons are transferred from QDs to Fe2+, which facilitates a nonradiative recombination process and a decrease in the PL efficiency. In addition, the results from time resolved photoluminescence and a confocal scanning fluorescence microscope have shown that smaller-size QDs have a faster decrease in the fluorescence lifetime compared with that of larger-size QDs with Fe2+ addition, suggesting that the fast charge transfer in smaller-size QDs should be responsible for the observed fluorescence quenching effect. This Letter provides a comprehensive understanding of the mechanism of the fluorescence for the CdTe QDs quenched by Fe2+.

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

“…A similar behavior of lifetime has been obtained for the QDs in the presence of the above mentioned other first-row TM ions. This suggests that the excited energy states corresponding to band-edge emission (having decay component τ 1 ) as well as the trap states (having decay component τ 2 , τ 3 ) are involved in the photoinduced charge transfer process from QDs to metal ions . The thermodynamic feasibility of the PET from QDs to first-row TM ions (Mn 2+ , Fe 2+ , Ni 2+ , Co 2+ , and Cu 2+ ) is shown later ( vide infra ).…”

Density-Dependent Carrier Recombination in MoS2Quantum Dots and Its Implications for Luminescence Sensing of Ammonium Hydroxide

“…Thus, the NH 4 OH concentration can be detectable by measuring the PL quenching of MoS 2 QDs, especially for QDs with high carrier densities. The PL quenching mechanism in MoS 2 QDs under increasing NH 4 OH concentrations was analyzed by the Stern–Volmer relation: where F O , F , K SV , and [ Q ] represents the PL intensity without NH 4 OH, PL intensity with NH 4 OH, the quenching constant, and the concentration of NH 4 OH, respectively. Figure a shows the fitted results using eq , which agrees with the experimental data and indicates a linear response over the range 10–1500 μM.…”

“…The fitted parameters for the Stern–Volmer plots are provided in Table S2. In general, PL quenching can be related to dynamic or static quenching. , To determine the possible origin of the quenching mechanism, the TRPL measurements of MoS 2 QDs with the introduction of NH 4 OH were measured. Figure b displays the PL decay transients of the MoS 2 QDs ( p = 2.08 × 10 12 cm –2 ) with increasing NH 4 OH concentrations.…”

Amorphous B-doped graphitic carbon nitride quantum dots with high photoluminescence quantum yield of near 90% and their sensitive detection of Fe2+/Cd2+

“…The quantum confinement, surface state, and size effects of QDs give rise to intriguing properties in the resultant optical and electronic structures and conferring them with much broader applicability and higher fluorescence quantum yields (QYs) compared with traditional FDT materials [9][10][11][12]. Several QD-based FDT materials, such as CdS/CdTe [13][14][15], graphene [16][17][18], and carbon QDs, have recently been developed [19,20]. Unfortunately, the presence of heavy metals and potentially carcinogenic organic molecules in the majority of the available QDs could give rise to environmental problems and biological toxicity.…”