title: Highly sensitive determination of the polaron-induced optical absorption of organic charge-transport materials.
abstract: We examine polaron-induced absorption in organic transport materials using a highly sensitive measurement technique. A hole only device is embedded into a low-loss TE2 waveguide structure, and the current induced change of the waveguide absorption is measured. The exemplary study of 2,2('),7,7(')-tetrakis(N,N-diphenylamine)-9,9(')-spiro-bifluorene (S-TAD) reveals a very low polaron absorption cross section of sigma(p) < or = 2.6 x 10(-18) cm(2) for 560 nm < or = lambda < or = 660 nm. The accuracy of this data is unsurpassed by other techniques used for the unambiguous study of polaronic species in organic thin films.
authors.affiliation: Institut für Hochfrequenztechnik, Technische Universität Braunschweig, Schleinitzstrasse 22, 38106 Braunschweig, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Rabe
authors.forename: P
authors.initials: P
authors.lastname: Görrn
authors.forename: M
authors.initials: M
authors.lastname: Lehnhardt
authors.forename: M
authors.initials: M
authors.lastname: Tilgner
authors.forename: T
authors.initials: T
authors.lastname: Riedl
authors.forename: W
authors.initials: W
authors.lastname: Kowalsky