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Mobility of charge carriers in self-assembled monolayers
Zhihua Fu1, Tatjana Ladnorg1, Hartmut Gliemann1
1Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Campus Nord, 76344 Eggenstein-Leopoldshafen, Germany.
Beilstein Journal of Nanotechnology
|January 11, 2020
Summary
We developed a new atomic force microscopy (AFM) method to precisely measure charge transport in organic semiconductors (OSCs). This technique reveals intrinsic charge carrier mobility in thin films, overcoming limitations of traditional methods.
Area of Science:
- Materials Science
- Organic Electronics
- Surface Science
Background:
- Studying charge transport in 2D organic semiconductor (OSC) layers is crucial for electronic device development.
- Conventional methods for measuring charge carrier mobility in OSCs are often affected by defects and grain boundaries.
- Atomic force microscopy (AFM) offers high-resolution surface analysis capabilities.
Purpose of the Study:
- To present a novel AFM-based lithography approach for investigating lateral charge transport in 2D OSC layers.
- To demonstrate a method for fabricating insulating barriers within OSC self-assembled monolayers (SAMs).
- To determine the relationship between OSC island size and electrical conductivity for mobility assessment.
Main Methods:
- Utilizing AFM-based lithography to create insulating patches within OSC SAMs using large band gap alkanethiolates.
- Fabricating SAMs from phenyl-linked anthracenethiolate (PAT) molecules.
- Measuring current-voltage (I-V) characteristics of PAT islands with the AFM tip acting as a top electrode.
Main Results:
- Established a correlation between the size of PAT islands and their electrical conductivity.
- Successfully obtained information on lateral charge transport and charge carrier mobility within thin OSC layers.
- Demonstrated that AFM nanografting allows for the determination of intrinsic mobilities, minimizing the impact of defects.
Conclusions:
- AFM nanografting is a viable technique for accurately determining intrinsic charge carrier mobilities in OSC thin films.
- This method provides a pathway to study charge transport phenomena with reduced influence from structural imperfections.
- The findings enable more reliable characterization of organic semiconductor materials for advanced electronic applications.
