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Switches from pi- to sigma-bonding complexes controlled by gate voltages
Eriko Matsui1, Oliver Harnack, Nobuyuki N Matsuzawa
1Materials Laboratories, Sony Corporation, Atsugi, Kanagawa, Japan.
Journal of Nanoscience and Nanotechnology
|October 26, 2005
Summary
This study shows that applying gate voltage to a polymer/metal ion/liquid-crystal system switches conductivity by changing the dominance of pi and sigma complexes. The sigma complex, dominant under gate voltage, exhibits higher conductivity than the pi complex.
Area of Science:
- Materials Science
- Organic Electronics
- Molecular Systems
Background:
- Conjugated polymers are key in organic electronics.
- Liquid-crystal systems offer tunable properties.
- Metal ion integration can modify electronic behavior.
Purpose of the Study:
- Investigate the electrical properties of a conjugated polymer/metal ion/liquid-crystal system.
- Determine the role of gate voltage in modulating conductivity.
- Characterize the molecular complexes present and their conductivity.
Main Methods:
- Fabrication of a molecular system between source and drain electrodes.
- Application of varying gate voltage (Vg).
- Infrared spectroscopy for complex identification.
- Conductivity calculations for different molecular states.
Main Results:
- Increased source-drain current with increasing gate voltage.
- Identification of pi and sigma complexes via infrared spectra.
- Shift from pi-complex dominance (at Vg=0) to sigma-complex dominance (at Vg > 0).
- Calculated lower conductivity for the pi complex compared to the sigma complex.
Conclusions:
- Gate voltage effectively controls the conductivity of the conjugated polymer/metal ion/liquid-crystal system.
- The observed conductivity modulation is attributed to the gate-induced shift in dominance between pi and sigma complexes.
- The sigma complex is a more conductive state than the pi complex in this molecular system.