Efficient solar cells are more stable: the impact of polymer molecular weight on performance of organic photovoltaics

Ding, Z., Kettle, J., Horie, M., Chang, S. W., Smith, G. C., Shames, A. I. and Katz, E. A. (2016) Efficient solar cells are more stable: the impact of polymer molecular weight on performance of organic photovoltaics. Journal of Materials Chemistry A, 4(19), pp. 7274-7280. (doi: 10.1039/C6TA00721J)

Abstract

The principle remaining challenge in the research area of organic photovoltaic (OPV) materials is to develop solar cells that combine high efficiency, stability and reproducibility. Here, we demonstrate an experimental strategy which has successfully addressed this challenge. We produced a number of samples of the highly efficient PTB7 polymer with various molecular weights (Mn ∼ 40–220k). OPV cells fabricated with this polymer demonstrated significant improvement of the cell efficiency (by ∼90% relative) and lifetime (by ∼300% relative) with the Mn increase. We attribute these effects to the lower density of recombination centers (persistent radical defects revealed by EPR spectroscopy) and better photoactive layer morphology in the samples with higher Mn. Relevance of the observed correlation between the OPV efficiency and stability is discussed.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Kettle, Professor Jeff
• Authors: Ding, Z., Kettle, J., Horie, M., Chang, S. W., Smith, G. C., Shames, A. I., and Katz, E. A.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Journal of Materials Chemistry A
• Publisher: oyal Society of Chemistry
• ISSN: 2050-7488
• ISSN (Online): 2050-7496
• Published Online: 14 April 2016
• Copyright Holders: This journal is © The Royal Society of Chemistry 2016
• First Published: First published in J. Mater. Chem. A 2016 4:7274-7280
• Publisher Policy: Reproduced under a Creative Commons licence