Get access

Impact of UV-Visible Light on the Morphological and Photochemical Behavior of a Low-Bandgap Poly(2,7-Carbazole) Derivative for Use in High-Performance Solar Cells

Authors

  • Aurélien Tournebize,

    1. Clement Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, CNRS, UMR 6296, ICCF, Equipe Photochimie, BP 80026, F-63171 Aubière, France
    Search for more papers by this author
  • Pierre-Olivier Bussière,

    1. Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, Clermont Université, ENSCCF, LPMM, BP 10448, F-63000 Clermont-Ferrand, France
    Search for more papers by this author
  • Pascal Wong-Wah-Chung,

    1. Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, Clermont Université, ENSCCF, LPMM, BP 10448, F-63000 Clermont-Ferrand, France
    Search for more papers by this author
  • Sandrine Thérias,

    1. Clement Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, CNRS, UMR 6296, ICCF, Equipe Photochimie, BP 80026, F-63171 Aubière, France
    Search for more papers by this author
  • Agnès Rivaton,

    Corresponding author
    1. Clement Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, CNRS, UMR 6296, ICCF, Equipe Photochimie, BP 80026, F-63171 Aubière, France
    • Clement Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, CNRS, UMR 6296, ICCF, Equipe Photochimie, BP 80026, F-63171 Aubière, France
    Search for more papers by this author
  • Jean-Luc Gardette,

    1. Clement Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, Equipe Photochimie, BP 10448, F-63000 Clermont-Ferrand, France, CNRS, UMR 6296, ICCF, Equipe Photochimie, BP 80026, F-63171 Aubière, France
    Search for more papers by this author
  • Serge Beaupré,

    1. Canada Research Chair on Electroactive and Photoactive Polymers, Département de Chimie, Université Laval, Quebec City, QC G1K 7P4, Canada
    Search for more papers by this author
  • Mario Leclerc

    Corresponding author
    1. Canada Research Chair on Electroactive and Photoactive Polymers, Département de Chimie, Université Laval, Quebec City, QC G1K 7P4, Canada
    • Canada Research Chair on Electroactive and Photoactive Polymers, Département de Chimie, Université Laval, Quebec City, QC G1K 7P4, Canada.
    Search for more papers by this author

Abstract

This paper reports on the photochemical behavior upon exposure to UV-visible light of a poly(2,7-carbazole) derivative for use in high-performance solar cells. Poly[N-9′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) is one of a relatively large class of push-pull carbazole-based copolymers that have been synthesized to better harvest the solar spectrum. The 2,7-carbazole building block of PCDTBT is also used with different electron-accepting units in a large variety of low-band-gap polymers. The photochemical and morphological behavior of PCDTBT thin films is investigated from the molecular scale to the nanomechanical properties. The photo-oxidation mechanism is shown to be governed by chain-scission and cross-linking reactions. It results in dramatic evolution of the morphology, roughness and stiffness of thin PCDTBT films. Based on the identification of several photoproducts formed along the macromolecular chains or released into the gas phase, the main pathways of PCDTBT photochemical evolution are discussed. These processes first involve the scission of the C–N bond between the carbazole group and the tertiary carbon atom bearing the alkyl side-chain. Modifications of the chemical structure of PCDTBT, the evolution of its UV-visible absorbance, and its nanomechanical properties initiated by light irradiation are shown to be closely related.

Get access to the full text of this article

Ancillary