Electron-phonon coupling in anthracene-pyromellitic dianhydride

Area of Science:

• Solid State Physics
• Materials Science
• Organic Electronics

Background:

• Understanding electron-phonon coupling is crucial for organic semiconductor performance.
• Anthracene-pyromellitic dianhydride (A-PMDA) is a mixed-stack organic semiconductor with potential applications.
• Previous studies have not fully characterized the electron-phonon coupling in A-PMDA.

Purpose of the Study:

• To determine the electron-phonon coupling constants for the charge transfer (CT) exciton in A-PMDA.
• To quantify the contributions of intramolecular and intermolecular phonons to the total reorganization energy.
• To compare experimental findings with theoretical density functional theory (DFT) calculations.

Main Methods:

• Experimental measurement using resonant Raman and absorption spectroscopy.
• Application of a time-dependent resonant Raman model.
• Comparison with DFT-derived theoretical estimates for reorganization energies.

Main Results:

• Electron-phonon coupling constants were successfully determined for A-PMDA.
• Experimental reorganization energies closely matched theoretical DFT calculations.
• Intramolecular phonons were identified as the primary contributors to the total reorganization energy.

Conclusions:

• This study provides a comprehensive analysis of electron-phonon coupling in A-PMDA, including all Raman-active phonons.
• The dominance of intramolecular phonons in the reorganization energy was confirmed.
• Evidence for orientational disorder in A-PMDA at 80 K was observed through absorption line shape analysis.