title: Thermally induced anchoring of fullerene in copolymers with Si-bridging atom: Spectroscopic evidences.
abstract: We use X-ray photoelectron spectroscopy (XPS), Near-edge X-ray absorption fine structure (NEXAFS), resonant Auger spectroscopy (RAS), Attenuation Total Reflection Infrared (ATR-IR) and Atomic Force Microscopy (AFM) to study the blend between the copolymer poly[2,7-(9,9-bis(2-ethylhexyl)-dibenzosilole)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole] (PSiF-DBT) and the fullerene derivative PC71BM submitted to different annealing temperatures. Those measurements indicate that there is an incidental anchoring of a fullerene derivative to the Si-bridging atoms of a copolymer induced by thermal annealing of the film. Insights about the physical properties of one possible PSiF-DBT/PC71BM anchored structure are obtained using Density Functional Theory calculations. Since the performance of organic photovoltaic based on polymer-fullerene blends depends on the chemical structure of the blend components, the anchoring effect might affect the photovoltaic properties of those devices.
authors: Department of Physics, Federal University of Paraná, Curitiba 81531-990, Brazil.
authors: Cleber F N
authors: CFN
authors: Marchiori
authors: Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909, Brazil.
authors: Yunier
authors: Y
authors: Garcia-Basabe
authors: Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909, Brazil.
authors: Fabio
authors: F
authors: de A Ribeiro
authors: Department of Physics, Federal University of Paraná, Curitiba 81531-990, Brazil.
authors: Marlus
authors: M
authors: Koehler
authors: Department of Physics, Federal University of Paraná, Curitiba 81531-990, Brazil. Electronic address: lsroman@fisica.ufpr.br.
authors: Lucimara S
authors: LS
authors: Roman
authors: Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909, Brazil. Electronic address: luiza@iq.ufrj.br.
authors: Maria Luiza M
authors: MLM
authors: Rocco
keywords: Density functional theory calculations; Photoelectron spectroscopy; Si-bridging donor-acceptor copolymers; X-ray absorption spectroscopy