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Large surface relaxation in the organic semiconductor tetracene
Hazuki Morisaki1, Takashi Koretsune2, Chisa Hotta3
1Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Japan.
Nature Communications
|November 8, 2014
Summary
Organic semiconductor surfaces undergo significant structural relaxation in the first molecular layer. This surface relaxation alters charge carrier transport properties in organic field-effect transistors.
Area of Science:
- Materials Science
- Solid-State Physics
- Organic Electronics
Background:
- Organic crystals exhibit significant surface relaxation due to weak intermolecular forces.
- Understanding surface structural changes is crucial for designing efficient organic field-effect transistors (OFETs).
- Carrier transport in OFETs is sensitive to structural modifications within the first few molecular layers.
Purpose of the Study:
- To directly observe and quantify the surface relaxation of an organic semiconductor.
- To investigate the impact of surface relaxation on electronic properties.
Main Methods:
- X-ray crystal truncation rod (CTR) scattering measurements were employed for direct observation.
- First-principles calculations were performed to analyze the electronic structure and transfer integrals.
Main Results:
- Direct observation confirmed significant surface relaxation in tetracene single crystals.
- Relaxation was localized to the outermost monolayer of the organic semiconductor surface.
- Calculations revealed distinct differences in transfer integrals between the bulk and surface.
Conclusions:
- The study provides direct experimental evidence of monolayer-specific surface relaxation in organic semiconductors.
- Surface relaxation profoundly impacts charge transport properties by altering electronic coupling.
- These findings are critical for the rational design of high-performance organic electronic devices.
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