Fabrication of Low Cost 1D CdSe Nanowires using Near-field Electrospinning
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Fabrication of Low Cost 1D CdSe Nanowires using Near-field Electrospinning Leroy Magwood1 and Binil Starly1,2 School of Industrial Engineering University of Oklahoma Norman, OK 73019, USA. 2 University of Oklahoma Bioengineering Center University of Oklahoma Norman, OK 73019, USA.
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ABSTRACT Well-aligned, 1D CdSe quantum dot (QD) fibers (0.3µm to 2.5µm) containing up to 20wt% fluorescent quantum dots (QDs) were prepared by near-field electrospinning (NFES) process. Electrospun solutions were prepared using PVAc as the matrix polymer, dimethyl formamide (DMF) solvent and colloidal QDs in chloroform (CHCl3). The diameter of the fibers decreased as the ratio of DMF/CHCl3 is varied. QDs showed good dispersion and a linear relationship between QD loading and fiber diameter, as determined by the morphology measurements taken using TEM and SEM, respectively. Fluorescence microscopy shows that there is light attenuation throughout the fibers. Results also show that the NFES process may be used as a method to create aligned, 1D fibers of QDs and potentially other nanofibers. INTRODUCTION Research on 1D nanomaterials is advancing rapidly as the size dependent optical, electrical, and mechanical properties have increased the reliability of nanodevices such as optoelectronic devices and bio/environmental sensors[1-2]. The controlled generation and organization of semiconductor 1D structures has demonstrated promise in applications such as nanolasers, solar cells, light-emitting diodes (LEDs), waveguides, photosensors and photodetectors[2-6]. Much of this promise is inherent to the material selection. One of the more promising materials incorporated into 1D structures - semiconducting nanocrystals, has shown that the high surfaceto-volume ratio found in 1D nanostructures is capable of increasing the sensing capability, conductivity, and luminescence[7,8]. Currently, the most widely used technique for the realization of 1D nanostructure is lithography, which is expensive and time consuming [8]. In this contribution, we present the near-field electrospinning process as a method to create 1D dimensional, well aligned CdSe composite fibers with diameters in the sub-micron scales. QDs are first synthesized using well defined protocols[9]. Poly(vinyl acetate) (PVAc), a non toxic polymer which is also a popular material for electrospinning was employed as the host matrix since the QDs do not require coating. The use of the near-field electrospinning (NFES) process allowed for well confined QDs in oriented fibers. NFES fiber morphology has been characterized using scanning electron microscopy (SEM). QD distribution within fibers has been evaluated by transmission electron microscopy (TEM). Optical properties of the composite fibers were investigated by UV-vis.
EXPERIMENT Materials: Trioctylphosphine oxide (TOPO), tributylphosphine (TBP), hexadecylamine, octadecylamine, stearic acid (SA), polyvinyl acetate (PVAc), dimethylforamide (DMF), CdO and Se powder were purchased from Aldrich. Methanol, dodecylamine, chloroform, and acetone we
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