Highly sensitive determination of the polaron-induced optical absorption of organic charge-transport materials.
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.
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Institut für Hochfrequenztechnik, Technische Universität Braunschweig, Schleinitzstrasse 22, 38106 Braunschweig, Germany.
Görrn
P
P
Lehnhardt
M
M
Tilgner
M
M
Riedl
T
T
Kowalsky
W
W