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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Influence of Molecular Dynamics on the Dielectric Properties of Poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) -Based Devices

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Author(s):
Faria, G. C. [1] ; von Seggern, H. [1] ; Faria, R. M. [2] ; deAzevedo, E. R. [2]
Total Authors: 4
Affiliation:
[1] Tech Univ Darmstadt, Inst Mat Sci, D-64287 Darmstadt - Germany
[2] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION; v. 19, n. 4, p. 1181-1185, AUG 2012.
Web of Science Citations: 2
Abstract

This paper uses Nuclear Magnetic Resonance (NMR) and Differential Scanning Calorimetry (DSC) techniques to study the molecular relaxations and phase transitions in poly(9,9-di-n-octylfluorene-alt-benzothiadiazole) (F8BT), which has been extensively studied as the active thin film in organic devices. Besides the identification of the glass transition, beta relaxation and crystal-to-crystal phase transition, we correlate such phenomena with dielectric and transport mechanisms in diodes with F8BT as the active layer. The beta relaxation has been assigned to a transition at about 210 K measured by H-1 and C-13 solid state NMR, and can be attributed to local motions in the side chains. The glass transition has been detected by DSC and H-1 NMR. Dielectric spectroscopy (DS) carried out at low frequencies on diodes made from F8BT show two peaks which are coincident with the above transitions. This allowed us to correlate the electrical changes in the film with the onset of specific molecular motions. In addition, DS indicates a third peak related with a crystal-to-crystal phase transition. Finally, these transitions were correlated with changes in the carrier mobility recorded in thin films and published recently. (AU)

FAPESP's process: 07/08688-0 - Electronic and optoelectronic polymer devices
Grantee:Roberto Mendonça Faria
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 08/01935-5 - Correlation between electric and optical properties with molecular dynamics and physical structure of films and organic devices of polyfluorenes and its derivatives
Grantee:Gregório Couto Faria
Support Opportunities: Scholarships in Brazil - Doctorate
FAPESP's process: 09/18354-8 - Dynamics and structure of polymer systems as studied by nuclear magnetic resonance
Grantee:Eduardo Ribeiro de Azevedo
Support Opportunities: Regular Research Grants