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Fast Singlet Exciton Decay in Push-Pull Molecules Containing Oxidized Thiophenes
Erik Busby1,2, Jianlong Xia1, Jonathan Z Low1
1†Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States.
The Journal of Physical Chemistry. B
|February 6, 2015
Summary
Introducing thiophene-1,1-dioxide as an acceptor in organic semiconductors unexpectedly shortens excited-state lifetimes. This tunability impacts optoelectronic applications by altering molecular properties.
Area of Science:
- Materials Science
- Organic Electronics
- Photochemistry
Background:
- Low-bandgap organic semiconductors are often synthesized using "push-pull" building blocks.
- Strong electron-accepting "pull" units are crucial for reducing optical gaps and developing n-type materials.
Purpose of the Study:
- To investigate the impact of thiophene-1,1-dioxide as a strong acceptor in "push-pull" oligomers.
- To understand how this acceptor affects electronic structure and carrier dynamics.
Main Methods:
- Synthesis of "push-pull" oligomers incorporating thiophene-1,1-dioxide.
- Spectroscopic analysis to determine electronic structure and excited-state dynamics.
Main Results:
- Thiophene-1,1-dioxide significantly reduces excited-state lifetimes by several orders of magnitude compared to unoxidized analogs.
- Introduction of low-energy, optically dark states and triplet states facilitates rapid internal conversion and intramolecular singlet fission.
- Electronic structure and excited-state lifetime show strong dependence on the number of sequential thiophene-1,1-dioxide units.
Conclusions:
- The incorporation of thiophene-1,1-dioxide offers a powerful strategy to tune the optoelectronic properties of organic semiconductors.
- Small chemical modifications can lead to drastic changes in static and dynamic optical properties, influencing material applications.
- This research provides insights into designing novel organic electronic materials with tailored photophysical characteristics.
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