Quantum-Confined Emission and Fluorescence Blinking of Individual Exciton Complexes in CdSe Nanowires

Abstract

One-dimensional semiconductor nanostructures combine electron mobility in length direction with the possibility of tailoring the physical properties by confinement effects in radial direction. Here we show that thin CdSe quantum nanowires exhibit low-temperature fluorescence spectra with a specific universal structure of several sharp lines. The structure strongly resembles the pattern of bulk spectra but show a diameter-dependent shift due to confinement effects. Also the fluorescence shows a pronounced complex blinking behavior with very different blinking dynamics of different emission lines in one and the same spectrum. Time- and space-resolved optical spectroscopy are combined with high-resolution transmission electron microscopy of the very same quantum nanowires to establish a detailed structure-property relationship. Extensive numerical simulations strongly suggest that excitonic complexes involving donor and acceptor sites are the origin of the feature-rich spectra.

The Effect of Exciton‐Delocalizing Thiols on Intrinsic Dual Emitting Semiconductor Nanocrystals

“…The fact that the core of DDT is quenched more rapidly than the surface emission may be tied to the poor overlap between the core wavefunction and the newly delocalized hole. [21] Based on the results for DDT and ADMT,we conclude that the surface excitoni sn ot affected to the same extentb yt he hole delocalization as the core exciton. These results showed that in the case of DDT,t he decrease in the PL QY was tied to nonradiative decay of the core exciton.…”

“…This was accompanied by an increased surface‐state emission. The fact that the core of DDT is quenched more rapidly than the surface emission may be tied to the poor overlap between the core wavefunction and the newly delocalized hole . Based on the results for DDT and ADMT, we conclude that the surface exciton is not affected to the same extent by the hole delocalization as the core exciton.…”

ERS approximation for solving Schrödinger’s equation and applications

“…The behavior of the holes would be quite similar, but not treated here. Experimentally, the distribution of the lengths of the wurtzite and zincblend segments was found to be close to a geometric distribution with an average ofd=2.5 MLs (P (d) (1 − 1/d) d−1 /d) where d is the number of monolayers [33]. We used this distribution in our model of this system (shown in figure 3), assuming a 50% chance for each phase.…”

Surface Charges on CdSe-Dot/CdS-Rod Nanocrystals: Measuring and Modeling the Diffusion of Exciton-Fluorescence Rates and Energies

“…33 We performed similar three-dimensional calculations for exciton complexes in CdSe quantum nanowires. 34 They rely on the discretization of the single-particle Schrödinger equation on a three-dimensional spatial Cartesian grid and a diagonalization of the emerging system of linear equations. The nearest distance between adjacent grid points was set to 2.0 Å in all three dimensions.…”