Raman scattering gain in DOO-PPV films

Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United StatesMaxim N. Shkunov, Werner Gellermann, Akihiko Fujii, Katsumi Yoshino, and Z. Valy Vardeny "Raman scattering gain in DOO-PPV films", Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997). DOI: https://doi.org/10.1117/12.29552

Laser action in conducting polymers

We discuss both cooperative radiation and stimulated emission and consider their role in spectral narrowing of luminescent conducting polymers. We argue that cooperative radiation is favored in films with poor optical confinement. On the other hand, directional stimulated emission can be observed in dilute solution and thin films with superior optical confinement. Spectral narrowing in this case can be achieved by increasing either the excitation length or excitation intensity. The optical gain and loss coefficients are measured. Narrow line (approximately 1.5 cm-1) laser emission is observed in cylindrical microcavities formed by thin polymer films coated around glass fibers in the red and green spectral ranges. The cavity quality factors of these plastic lasers are mainly determined by selfabsorption and estimated to be about 5000.Optical Scnce, Engineering and Instrumentation '97, 1997, San Diego, CA, United StatesSergey V. Frolov, Maxim N. Shkunov, Z. Valy Vardeny, Masanori Ozaki, and Katsumi Yoshino "Laser action in conducting polymers", Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997). DOI: https://doi.org/10.1117/12.29552

Optical studies of native defects in π-conjugated donor-acceptor copolymers

We used multiple spectroscopies such as photoinduced absorption (PIA), magneto photoinduced absorption, and doping induced absorption for studying native defects in π-conjugated donor-acceptor copolymer chains of benzodithio-phene fluorinated benzotriazole. The PIA spectrum contains characteristic photoinduced absorption bands that are due to polarons and triplet exciton species, whose strengths have different dependencies on the modulation frequency, temperature, and laser excitation, as well as magnetic field response. We found that the native defects in the copolymer chains serve as efficient traps that ionize the photoexcited excitons, thereby generating charge carriers whose characteristic optical properties are similar, but not equal to those of intrachain polarons formed by doping. The native defects density is of the order of 1017 cm-3 indicating that most of the copolymer chains contain native defects upon synthesis; however, this does not preclude their used-for photovoltaic applications

Electromodulated photoinduced absorption : A new spectroscopy in π- conjugated polymer/C60 blends

Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United StatesMartin Liess, Paul A. Lane, Zakya H. Kafafi, M. Hamaguchi, Masanori Ozaki, Katsumi Yoshino, and Z. Valy Vardeny "Electromodulated photoinduced absorption: a new spectroscopy in π-conjugated polymer/C60 blends", Proc. SPIE 3142, Fullerenes and Photonics IV, (1 November 1997). DOI: https://doi.org/10.1117/12.29335

Near-infrared ps transient photoinduced absorption in conjugated systems

Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United StatesSergey V. Frolov, Werner Gellermann, Z. Valy Vardeny, Masanori Ozaki, Katsumi Yoshino, Thomas J. Barton, and Guglielmo Lanzani "Near-infrared ps transient photoinduced absorption in conjugated systems", Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997). DOI: https://doi.org/10.1117/12.29553

Studies of Raman scattering in novel disubstituted acetylene polymers

We have studied resonant and non-resonant Raman scattering spectra in thin films of novel disubstituted acetylene polymers such as poly(1-ethyl-2-phenylacetylene) (PEtPA), poly(1-n-hexyl-2-phenylacetylene) (PHxPA) and poly(1-phenyl- 2-p-n-butylphenylacetylene) (PDPA-nBu), which possess high photoluminescence (PL) quantum efficiency. We found that the Raman scattering frequency dispersion is smaller in disubstituted acetylene polymers than in other acetylene polymers, in agreement with many other strongly luminescent polymers. Assuming the model of short polyene conjugation length in these acetylene polymers, we can obtain the conjugation length (N) for each polymer from the respective phonon frequency of the carbon-carbon double bond; we obtained N equals 7 for PDPA-nBu, and N equals 5 or 6 for PHxPA and PEtPA. The related energies of 11Bu and 21Ag can be estimated from these N and are in good agreement with the respective absorption and PL spectra of the various disubstituted polymers.Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United StatesAkihiko Fujii, Maxim N. Shkunov, Z. Valy Vardeny, Kazuya Tada, Katsumi Yoshino, Masahiro Teraguchi, and Toshio Masuda "Studies of Raman scattering in novel disubstituted acetylene polymers", Proc. SPIE 3145, Optical Probes of Conjugated Polymers, (1 December 1997). DOI: https://doi.org/10.1117/12.29554