title: Conjugation Length Distribution in Poly(p-phenylenevinylene) (PPV) Films.
abstract: We studied the absorption line-shape of poly(p-phenylenevinylene) (PPV) films deposited via spin coating and Langmuir-Blodgett techniques with the intent of identifying the conjugation length distribution in these two types of films, a key morphological aspect of conjugated polymer films. We treated the excitons in the polymer as independent oligomer excitons and modeled the absorption spectra of the individual oligomers using simple expressions for the oligomer size dependence of the gap energy, the line-broadening factor, the transition dipole moment and the Huang-Rhys parameter. We validated these expressions by independent measurements on phenyl-based oligomers and Density Functional Theory calculations. Our results show clear evidence that, for both types of PPV films, the conjugation length distribution depends exponentially on the segment size. Our results also set a lower limit, of about ten repeat units, for the maximum exciton length of three different phenyl-based oligomers.
authors.affiliation: Center for Biological and Natural Sciences, Federal University of Acre , Rio Branco, Acre 69920-900, Brazil.
authors.forename: Marcelo C
authors.identifier: http://orcid.org/0000-0003-1324-6440
authors.initials: MC
authors.lastname: da Silva
authors.affiliation: Paulo Scarpa Polymer Laboratory (LaPPS), Federal University of Paraná , Curitiba, Paraná 80060-000, Brazil.
authors.forename: Sandra de M
authors.initials: SM
authors.lastname: Cassemiro
authors.affiliation: Paulo Scarpa Polymer Laboratory (LaPPS), Federal University of Paraná , Curitiba, Paraná 80060-000, Brazil.
authors.forename: Angelita M
authors.initials: AM
authors.lastname: Machado
authors.affiliation: Departamento de Física, Universidade Federal do Paraná , Curitiba, Paraná 80060-000, Brazil.
authors.forename: Joniel C F
authors.initials: JC
authors.lastname: Alves
authors.affiliation: Equipe Architectures Moléculaires et Matériaux Nanostruturés (AM2N), Institut Charles Gerhardt, ENSCM, 34090 Montpellier, France.
authors.forename: Sandra L
authors.initials: SL
authors.lastname: Nogueira
authors.affiliation: Equipe Architectures Moléculaires et Matériaux Nanostruturés (AM2N), Institut Charles Gerhardt, ENSCM, 34090 Montpellier, France.
authors.forename: Thibault
authors.initials: T
authors.lastname: Jarrosson
authors.affiliation: Equipe Architectures Moléculaires et Matériaux Nanostruturés (AM2N), Institut Charles Gerhardt, ENSCM, 34090 Montpellier, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Serein-Spirau
authors.affiliation: Paulo Scarpa Polymer Laboratory (LaPPS), Federal University of Paraná , Curitiba, Paraná 80060-000, Brazil.
authors.forename: Leni
authors.initials: L
authors.lastname: Akcelrud
authors.affiliation: Institute of Physics, Federal University of Uberlândia , Uberlândia, Minas Gerais 38408-100, Brazil.
authors.forename: José R
authors.initials: JR
authors.lastname: Tozoni
authors.affiliation: Institute of Physics, Federal University of Uberlândia , Uberlândia, Minas Gerais 38408-100, Brazil.
authors.forename: Raigna A
authors.initials: RA
authors.lastname: Silva
authors.affiliation: Departamento de Física, Universidade Federal do Paraná , Curitiba, Paraná 80060-000, Brazil.
authors.forename: José A
authors.identifier: http://orcid.org/0000-0001-5967-9677
authors.initials: JA
authors.lastname: Freire
authors.affiliation: Institute of Physics, Federal University of Uberlândia , Uberlândia, Minas Gerais 38408-100, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Marletta