XPS analysis of the chemical degradation of PTB7 polymers for organic photovoltaics

Kettle, J., Ding, Z., Horie, M. and Smith, G.C. (2016) XPS analysis of the chemical degradation of PTB7 polymers for organic photovoltaics. Organic Electronics, 39, pp. 222-228. (doi: 10.1016/j.orgel.2016.10.016)

Abstract

The chemical degradation of the Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] or ‘ PTB7’ has been studied using X-ray Photoelectron Spectroscopy (XPS). This material system appears to be intrinsically unstable especially when illuminated in air and XPS studies confirm the rapid photo-degradation is related to changes in chemical structure of the polymer. In particular, XPS spectra show an initial reduction in relative Csingle bondC intensity, suggests loss of the alkoxy side chains. This is followed by a dramatic increase in the level of oxygen-bonded species, especially Csingle bondO at ∼286.5 eV and C(=O)O at 289.2 eV, indicative of COOH and OH group formation, and oxidation of S. The XPS results support the view that using processing additives reduces the chemical stability of the polymer and provides insight into strategies to improve molecular design to ensure higher chemical stability.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Kettle, Professor Jeff
• Authors: Kettle, J., Ding, Z., Horie, M., and Smith, G.C.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Organic Electronics
• Publisher: Elsevier
• ISSN: 1566-1199
• ISSN (Online): 1878-5530
• Published Online: 14 October 2016

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