Photoluminescence of CdSe Nanoparticles in the Presence of a Hole Acceptor:  n-Butylamine

Abstract

Addition of butylamine to a solution of colloidal CdSe nanoparticles (NPs) caused a decrease in fluorescence intensity, with no effect on the picosecond bleach recovery of the exciton formation or on the luminescence dynamics. The relative fluorescence quantum yield was found to decrease with increasing butylamine concentration and to level off at high concentrations, but the fluorescence lifetimes were not influenced. The nonlinear concentration dependence of the fluorescence quantum yield did not follow the Stern−Volmer equation. This is in agreement with the observation that the CdSe luminescence lifetime was not affected by the addition of butylamine. A mechanism is proposed in which the emission observed in CdSe is assumed to result from the combination of surface-trapped electrons and holes. n-Butylamine occupies hole sites, thus blocking the recombination process, which results in decreasing the density of luminescent centers. These results will be discussed in terms of the nature of the binding sites of the amine on the nanoparticle surface.

Fluorescence Quenching of Quantum Dots by DNA Nucleotides and Amino Acids

“…Amines, for example, have been found to quench fluorescence in some cases, suggesting interactions with surface holes. [13] However, many other publications report fluorescence enhancement, instead suggesting a completely different kind of interaction. [30] This contradiction might be solved by the observation that properties of QD depend not only on the material but also on the particle synthesis and surface coating.…”

“…This notion is supported by recent reports of aliphatic amines and mercaptanes effecting the fluorescence emission of CdSe cores. [13,18,22] Although the QD are shielded not only by a ZnS shell, but also by polymer coating and biofunctionalization, one might imagine small molecules, like dNTP, penetrating the streptavidin and eventually also the polymer coating. Recently, non-uniformity of ZnS shells was reported, suggesting partially thin ZnS layers could even contain pores that could form potential binding sites for quenchers.…”

“…In current literature, quenching of QD by metal ions, such as Cu 2þ and Ag þ , and by organic molecules containing amino-groups have been reported. [11][12][13] Influence of various compounds on the fluorescence emission properties of QD raised a strong interest in their use as fluorescent sensors, like the quenching by metal ions, [12,14,15] gold nanoparticles, [16,17] and various other compounds. [18][19][20][21][22][23] Further studies focussed on the oxidation of QD, [24] or photo-induced charge transfer, [11] and also on the influence of experimental conditions, such as temperature or pH.…”

Labeling of HeLa cells using ZrO 2 : Yb 3 + - Er 3 + nanoparticles with upconversion emission

“…These elements may act as quenching centers of luminescence and also create defects, which behave as traps for luminescence. 71,72 It is important to point out that the sample with APTES-Biotin had the highest levels of impurities [see Fig. 3(c)]; therefore, it showed the lowest luminescence.…”

Ultrafast Carrier Dynamics in Exfoliated and Functionalized Calcium Niobate Nanosheets in Water and Methanol

“…Surface passivation can virtually eliminate PL 54 as a result of the elimination of trapped hole states, as has been demonstrated in nanocrystalline chalcogenides. [55][56][57][58] …”