Modification of Blinking Statistics in Solid State Quantum Dot/Conjugated Organic Polymer Composite Nanostructures
- PDF / 1,896,878 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 0 Downloads / 169 Views
0959-M02-03
Modification of Blinking Statistics in Solid State Quantum Dot/Conjugated Organic Polymer Composite Nanostructures Nathan I. Hammer1, Kevin T. Early1, Michael Y. Odoi1, Ravisubhash Tangirala2, Kevin Sill2, Todd Emrick2, and Michael D. Barnes1 1 Chemistry, University of Massachusetts, 710 North Pleasant, Amherst, MA, 01003 2 Polymer Science & Engineering, University of Massachusetts, Conte Center for Polymer Research, Amherst, MA, 01003
ABSTRACT Single-molecule spectroscopy combined with atomic force microscopy measurements reveal that CdSe quantum dots functionalized with oligo(phenylene vinylene), OPV, ligands exhibit modified optical properties such as suppression of blinking when compared to conventional TOPO covered or ZnS-capped CdSe quantum dots. The blinking suppression is shown to be highly sensitive to the degree of ligand coverage on the quantum dot surface and this effect is interpreted as resulting from charge transport from photoexcited OPV into vacant trap sites on the quantum dot surface. This direct surface derivatization of quantum dots with organic ligands also enables a “tunable” quantum dot surface that allows dispersion of quantum dots in a variety of polymer supported thin films without phase segregation. This facilitates straightforward inclusion of these new hybrid materials into solid state formats and suggests exciting new applications of composite quantum dot/organic systems in optoelectronic systems. INTRODUCTION Fluorescence intermittency, or “blinking” in quantum dot systems has been the subject of great interest since the first observation of this phenomenon nearly 10 years ago [1-3]. The stability of quantum dot fluorescence emission is especially important in the context of photovoltaic, optoelectronic, and biological applications, where device performance, or the ability to track labeled particles, is affected adversely by fluorescence intermittency [4-11]. Recently, accounts of blinking suppression in quantum dot systems have been reported [12,13]. In these accounts, electron donating moieties such as β-mercaptoethanol and mercaptoethylamine serve to passivate the surface of the quantum dot. Here, we report modified blinking statistics in CdSe quantum dots that possess oligo(phenylene vinylene), OPV, ligands bound to the quantum dot surface (CdSe-OPV nanostructures). Bulk blends of conjugated organic polymers with quantum dots have received a great deal of attention for their potential in advanced optoelectronic devices and photovoltaic energy-harvesting applications [6,7,10]. Among the interesting features of these bulk composite systems is the electronic communication between conjugated organic and quantum dot components, which results in enhanced fluorescence quantum yields, energy transfer, and charge transport in bulk thin films. Here, we show that composite CdSe-OPV nanostructures exhibit enhanced properties such as blinking suppression. Interestingly, the total integrated intensity emitted from the nanostructures and the average time spent in an “off” state (τo
Data Loading...
