Simple Surface-Trap-Filling Model for Photoluminescence Blinking Spanning Entire CdSe Quantum Wires

Abstract

The mechanism for synchronous photoluminescence intensity fluctuations, blinking, spanning entire micrometerlong CdSe quantum wires (Glennon, J. J.; Tang, R.; Buhro, W. E.; Loomis, R. A. Nano Lett. 2007, 7, 3290) is likely different than that commonly cited for semiconductor quantum dots. We present a simple model for the intensity blinking in quantum wires that is based on the dynamic, transient filling of surface-trap sites by photogenerated excitons and the emptying of these occupied trap sites. The model implements a kinetic Monte Carlo scheme and a dynamic photoluminescence quantum yield that depends on the fraction of trap sites filled. When a majority of the surface traps are filled, one-dimensional excitons are formed and a high emission efficiency is realized. Autocorrelation analysis of both experiment and simulation reveal the nonergodic kinetics governing the blinking phenomenon.

Suppressing the Fluorescence Blinking of Single Quantum Dots Encased in N-type Semiconductor Nanoparticles

“…Based on the experimental results, we propose an external electron transfer model for the fluorescence blinking suppression of QDs by modifying surface-trap-filling model50, the diffusive coordinate model5152, and the interfacial electron transfer model as we reported previously53, as shown in Fig. 4.…”

Bright Core–Shell Semiconductor Quantum Wires

“…We argued that after the surface traps on the CdSe QWs were filled with photogenerated carriers or excitons, radiative recombination of subsequently generated excitons was enabled, accounting for the high single-wire PL QEs under high excitation power densities. 37 Under low excitation power densities, the surface traps remained largely empty, and interaction of excitons with these traps made non-radiative recombination the dominant exciton-relaxation pathway. Kuno and coworkers have also reported that the PL QEs in single colloidal QWs increase under increasing excitation intensities of up to 3000 W/cm 2 , reaching values as high as 5–20%.…”

CdTe Nanowires studied by Transient Absorption Microscopy

“…invoke in blinking studies of QDs [13] and NWs [14]. Specifically, charge carrier trapping is a second order rate process, which depends on the concentrations of the free charge carriers and the empty trap sites.…”

“…Specifically, charge carrier trapping is a second order rate process, which depends on the concentrations of the free charge carriers and the empty trap sites. At high pump fluences the trap sites are filled up, which reduces the rate of trapping [13,14]. Subtracting the bi-exponential fit from the highest pump fluence decay of three different wires results in the traces shown in Fig.…”