Nature of photoexcitations in poly (paraphenylene vinylene) and its oligomers

✍ Scribed by Z. Shuai; J.L. Brédas; W.P. Su

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 526 KB
• Volume: 228
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)00961-9

✦ Synopsis

Within a theoretical approach including both electron-phonon and electron-electron interaction terms, we investigate the relaxation processes of photoexcited states in oligomers and long chains of poly(paraphenylene vinylene), PPV. With regard to the vibronic structure, we find that the Huang-Rhys factor decreases monotonically as chain length increases. Our direct calculations indicate that in PPV the difference in binding energy between two polarons and one singlet (triplet) polaron-exciton decreases (increases) with the Hubbard Uterm; the long-range interaction Vterms stabilize both the singlet and triplet polaronexcitons. The theoretically simulated photoinduced absorption spectra agree with experiment both for singlet and triplet states.