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Defect-Driven Polaron Localization in π-Conjugated Systems: The Role of Spatial Correlation and Coulomb Binding
Abhradeep Sarkar1, Amiya Paul1, Raja Ghosh1,2
1Department of Chemistry and Organic and Carbon Electronics Laboratories, North Carolina State University, Raleigh, North Carolina 27605, United States.
Journal of Chemical Theory and Computation
|October 23, 2025
Summary
Defect engineering in π-conjugated materials impacts polaron transport. Understanding defect types and dopant interactions is key to optimizing charge mobility in organic electronics.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Organic Electronics
Background:
- Defect engineering modulates polaron delocalization in π-conjugated materials.
- The interplay between defects and dopant-induced Coulomb binding is not fully understood.
Purpose of the Study:
- Theoretically investigate hole-polaron transport in π-conjugated lattices with defects and dopant effects.
- Clarify how defect types, spatial correlation, and dopant binding influence polaron delocalization and transport.
Main Methods:
- Utilized a Holstein-style Hamiltonian for theoretical investigation.
- Simulated mid-infrared signatures and polaron coherence numbers.
- Incorporated vacancy and linker defects, disorder, and dopant-induced Coulomb binding.
Main Results:
- Spatial correlation of defects dictates polaron delocalization pathways.
- Dopant counterions strongly localize polarons, with positioning critically affecting transport.
- Simulations revealed distinct polaron behaviors based on defect configurations.
Conclusions:
- Established guiding principles for optimizing polaron transport in disordered π-conjugated materials.
- Validated theoretical predictions through comparison with experimental mid-infrared spectra of doped P3HT films.
- Demonstrated the critical role of dopant-polymer configurations in anisotropic spectroscopic and transport properties.
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