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

Autor(es)

Faria, G. C. ^[1] ; von Seggern, H. ^[1] ; Faria, R. M. ^[2] ; deAzevedo, E. R. ^[2]

Afiliação do(s) autor(es)

^[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

• Tipo de documento: Artigo Científico
• Fonte: IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION; v. 19, n. 4, p. 1181-1185, AUG 2012.
• Citações Web of Science: 2

Resumo

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)

• Processo FAPESP: 07/08688-0 - Dispositivos eletrônicos e optoeletrônicos poliméricos
• Beneficiário: Roberto Mendonça Faria
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 08/01935-5 - Correlação das propriedades óticas e elétricas com a estrutura física e dinâmica molecular de filmes e dispositivos orgânicos de polifluorenos e derivados
• Beneficiário: Gregório Couto Faria
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 09/18354-8 - Dinâmica e estrutura de sistemas poliméricos estudados por ressonância magnética nuclear
• Beneficiário: Eduardo Ribeiro de Azevedo
• Modalidade de apoio: Auxílio à Pesquisa - Regular