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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.)

Molecular Origin of Charge Traps in Polyfluorene-Based Semiconductors

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Faria, Gregorio C. [1, 2] ; deAzevedo, Eduardo R. [1] ; von Seggern, Heinz [2]
Total Authors: 3
[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
[2] Tech Univ Darmstadt, Inst Mat Sci, D-64287 Darmstadt - Germany
Total Affiliations: 2
Document type: Journal article
Source: MACROMOLECULES; v. 46, n. 19, p. 7865-7873, OCT 8 2013.
Web of Science Citations: 10

The comprehensive control of morphology and structure is of extreme importance in semiconducting polymers when used as active layers in optoelectronic devices. In the work reported here, a systematic investigation of the structural and dynamical properties of poly(9,9-di-n-octyl-fluorene-alt-benzothiadiazole), known as F8BT, and their correlation with electrical properties is presented when the material is used as an active layer in optoelectronic devices. By means of X-ray diffraction, one observes that in thick layer films (thickness of about 4 pm) grown by drop-cast deposition, a solvent induced crystalline phase exists which evolves to a stable phase as the temperature is raised. This was not observed in thin films (thickness of about 250 nm) prepared by spin-coating within the investigated temperature range. By modeling the current-voltages characteristics of both thick and thin film devices, important information on the influence of crystallization on the trapping states could be drawn. Furthermore, the temperature dependence of the charge carrier mobility was found to be closely related to that of the molecular relaxation processes. The understanding of the nature of such molecular relaxations, measured by solid-state nuclear magnetic resonance methods, allows one to understand the importance of molecular relaxations and microstructure changes on the trap states of the system. (AU)

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 type: 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 type: Regular Research Grants
FAPESP's process: 07/08688-0 - Electronic and optoelectronic polymer devices
Grantee:Roberto Mendonça Faria
Support type: Research Projects - Thematic Grants
FAPESP's process: 12/01303-4 - Structural and morphological characterization of conjugated polymer films for application on high performance photo-voltaic devices
Grantee:Gregório Couto Faria
Support type: Scholarships in Brazil - Post-Doctorate