AVS 45th International Symposium
    Organic Electronic Materials Topical Conference Monday Sessions
       Session OE+EM-MoM

Invited Paper OE+EM-MoM5
Excited-State Electronic Structure of Conjugated Polymers and Oligomers: Characterization of the Luminescence and Two-Photon Absorption Properties

Monday, November 2, 1998, 9:40 am, Room 327

Session: Organic Thin Film Devices I: Light Emitters
Presenter: J.L. Brédas, University of Mons-Hainaut, Belgium
Correspondent: Click to Email
Conjugated polymers and oligomers present remarkable semiconducting and nonlinear optical properties. They can for instance be incorporated as the active element in new generations of organics-based field-effect transistors, light-emitting diodes, or photovoltaic cells; much work is also devoted to designing chromophores with enhanced second-order or third-order optical response. In this talk, we discuss the results of correlated quantum-chemical calculations aimed at characterizing the electronic structure of these excited states that are responsable for the luminescence and nonlinear optical properties. We focus on polyparaphenylene vinylene and its derivatives; these polymers are widely exploited in polymer-based light-emitting diodes. We describe the nature of the lowest singlet excited states involved in the absorption and emission processes. We then discuss the major influence of interchain interactions; by considering polyphenylenevinylene chains carrying different substituents, we show that some combinations lead to exciton transfer (which is good for luminescence) and others to charge transfer (which is good for photovoltaics). The second (brief) part of the talk deals with the design of novel donor-acceptor phenylenevinylene oligomers which display unprecedented two-photon absorption cross-sections. Some examples of potential applications will be briefly described.