Size-Dependence of Interfacial Electron Transfer from Single CdSe/ZnS Quantum Dots to TiO2 film
Date Issued
2011
Date
2011
Author(s)
Chang, Chun-Li
Abstract
The SMS (Single molecule spectroscopy) which combined confocal microscopy and TCSPC (Time-correlated single photon counting) system was used to detect the fluorescence trajectories and lifetimes of single semiconductor QD (Quantum dot) on a resolution of single molecule level, and the interfacial electron transfer kinetics between single QD and TiO2 film were investigated by this work. Three different diameters CdSe/ZnS QDs of 3.6, 4.6 and 6.4 nm were spin-coated on glass and TiO2 nanoparticles film, and the trajectories and lifetimes were investigated by the SMS with an excitation of 375 nm pulsed laser. The differences of lifetimes showed a size-dependent trend which increased with size decreased, and ET (Electron transfer) rate constants between the interface of QDs and TiO2 film were determined to be (1.5±1.4)×107 and (6.8±8.1)×106 s-1 for the sizes of 3.62 and 4.64 nm, the quantum yields of electron-ejection were also determined to be 22.6 and 13.3 %. However the ET rate constant of the largest size was hard to determine in this measurement due to the tiny difference of lifetimes. A truncated-power law was used to fit the probability density of on-state, and the parameters from the fitting were used to further calculate the ET rate constant by Marcus electron transfer model. The theoretical ET rate constants were determined to be 1.42×107, 6.80×106, and 1.86×106 s-1of three different sizes, and close to our experimental results.
Subjects
single molecule spectroscopy
single quantum dot
titanium oxide
electron transfer
blinking behavior
fluorescence lifetime
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-100-R98223158-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):fe334697bcc007649efe04712de55e9d