Manipulation, Assembly & Characterization. of Optically Functional 1-D Organic. Nanostructures.

Transcription

1 1 Manipulation, Assembly & Characterization of Optically Functional 1-D Organic Nanostructures. Authors: Ken Reynolds, P. Lovera, D. Iacopino, H. Doyle, A. O Riordan, G. Redmond. Nanotechnology Group Tyndall National Institute, Ireland.

2 2 1-D Nanostructures Inorganic 1-D Nanostructures Organic 1-D Nanostructures Inorganic 1-dimensional (1-D) nanostructures have been developed for next generation nanoelectronic and nanophotonics IBM, Intel, NASA, university labs. Recent interest in developing functional organic 1-D nanostructures because of highly tunable electronic and optical properties of organics. Controlled, high-yield assembly routes are required for viable 1-D nanodevices.

3 3 Bottom-up Assemblies: State of the Art Magnetic Electric Optical Probe Shear Langmuir- Blodgett

4 4 Organic Nanostructure Synthesis Poly(9,9-dioctylfluorenyl-2,7-diyl) a blue emitter Thermal & chemical stability. High PL quantum efficiencies (50-70 %) Chemically tunable emission. n R = C 8 H 17 Nanowires synthesized by solution wetting template method. 2 µm Nanowire shape: Cylindrical. Nanowire diameters: nm. Nanowire length: ~ 15 µm Nanowire yield: ~ µm

5 5 Custom built Probe System Liquid Nanowires on substrate Tungsten probe Optical sensor 3D actuator Z Y X Driver & DAC 100 µm Tungsten probe 3D actuator Z Y X X Y Glass stage Light in Amplifier & ADC Liquid Nanowires on substrate CCD camera 3D controller Glass stage * in collaboration with Dr. Marko Pudas, University of Oulu, Finland & NanoGalex Ltd. * Publication arising from this work submitted to Nanotechnology.

6 6 Manipulation of Inorganic Nanowires (a) (b) (c) Assembly times Square: 120s (d) (e) (f) Triangle: 180s Hexagon: 300s Average: 50s 20 µm (g) (h) (i) 15 µm Platinum Nanowires

7 7 Manipulation of Organic Nanowires PFO Nanowires Assembly times Square 1: 540s Line 1 (8 wires): 600s Square 2: 180s Line 2 (5 wires): 240s Triangle 1: 180s Average: 60s Triangle 2: 180s

8 8 Mesostructure Characterization 10 µm kcnts. kcnts 10 µm 200 axial Minimal damage to polymer nanowires. Net alignment of the polymer chains parallel to the long axis of each wire. 1.5 kcnts NW mesostructure longer wire bent to form 2 sides of a triangle.

9 9 PFO nanowires Nanowire diameter 230 nm + = Hybrid inorganic/organic nanostructures Nanocrystal doped PFO nanowires Doping had minimal effect on NW s internal molecular structure & optical properties. 20 nm Fe3O4 nanocrystals. Nanocrystals Magnetically doped Organic Nanowires

10 10 Magnetic Manipulation of Organic Nanowires Magnet 765 cnts 10 µm Magnetic extraction Static magnetic alignment 100 Superparamagnetic response Alignment characterization

11 Nanowire suspension Magnet 11 Magnetic Manipulation of an Organic Nanowire Dynamic Magnetic Manipulation Microscope lens Glass Coverslip Pulley Nanowire length: 12µm Polymer nanowire based nanorotor

12 12 Clocking an organic nanorotor by monitoring its intrinsic emission anisotropy Magnet Nanowire suspension Glass Coverslip Microscope lens Optical Measurement System with polariser and APD Single nanowire rotated by a magnet and its photoemission measured by an APD having passed through a longitudinal polariser

13 13 Clocking an organic nanorotor by monitoring its intrinsic emission anisotropy (a) (b) (a) (c) (d) (c) (b) (d) 4 µm Monitoring the wires intrinsic emission anisotropy results in a π/2 sinusoidal modulation of fluorescence intensity recorded at an APD.

14 14 Optical Trapping of Organic Nanostructures For a PFO NW of L = 3 µm, φ = 250 nm, spring constant k: pn/µm. Future work (1) nanowires/tubes interactions (2) k-based sorting of various nanowires values. (3) Large scale assembly using holographic optical trapping. * in collaboration with Dr. Phil Jones, University College London, UK. & Prof. John Ketterson, Northwestern University, USA.

15 15 Optical Trapping of Organic Nanostructures Abs. 1PL 2PL 850 nm Fluorescence F8BT nanotube is trapped vertically in a static trap then pulled into the horizontal and shown in three different orientations. While in trap laser induces 2-photon emission in nanotube. Not seen in PFO. Possible application: Nanotube based scanning probe.

16 16 Summary Developed a range of synthesis and assembly methodologies for organic nanostructures. Probe-based system for rapid prototyping of 1-D naostrucutre based devices/systems. Developed hybrid organic/inorganic nanostructures. Demonstration of a doped polymer nanowire as a nanoroter undergoing 360 rotation under the influence of a rotating NbFeB magnet while clocking its polarized fluorescence. First demonstration of polymer nanowires and nanotubes manipulated using an optical trap.