Effect of annealing on exciton diffusion in a high performance small molecule organic photovoltaic material

Long, Y., Hedley, G. , Ruseckas, A., Chowdhury, M., Roland, T., Serrano, L. A., Cooke, G. and Samuel, I. D.W. (2017) Effect of annealing on exciton diffusion in a high performance small molecule organic photovoltaic material. ACS Applied Materials and Interfaces, 9(17), pp. 14945-14952. (doi:10.1021/acsami.6b16487) (PMID:28358189) (PMCID:PMC5423077)

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Abstract

Singlet exciton diffusion was studied in the efficient organic photovoltaic electron donor material DTS(FBTTh2)2 . Three complementary time-resolved fluorescence measurements were performed: quenching in planar heterojunctions with an electron acceptor; exciton-exciton annihilation; and fluorescence depolarization. The average exciton diffusivity increases upon annealing from 1.6 ×〖10〗^(-3) 〖cm〗^2 s^(-1) to 3.6 ×〖10〗^(-3) 〖cm〗^2 s^(-1), resulting in an enhancement of the mean two–dimensional exciton diffusion length (L_D=√4Dτ) from 15 nm to 27 nm. About 30% of the excitons get trapped very quickly in as-cast films and remain immobilized throughout their entire lifetime, whilst the remaining excitons diffuse with a similar rate to the excitons in the annealed films. The high exciton diffusion coefficient of the material leads to it being able to harvest excitons efficiently from large donor domains in bulk heterojunctions.

Item Type:Articles
Additional Information:The authors are grateful to the Engineering and Physical Sciences Research Council of the UK for financial support through grants EP/L505079/1, EP/L017008/1 and EP/J009016/1 and to The European Research Council of the European Union for support through grant 321305. I.D.W.S. acknowledges support from a Royal Society Wolfson Research Merit Award.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hedley, Dr Gordon and Cooke, Professor Graeme
Authors: Long, Y., Hedley, G., Ruseckas, A., Chowdhury, M., Roland, T., Serrano, L. A., Cooke, G., and Samuel, I. D.W.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:ACS Applied Materials and Interfaces
Publisher:American Chemical Society
ISSN:1944-8244
ISSN (Online):1944-8252
Published Online:30 March 2017
Copyright Holders:Copyright © 2017 American Chemical Society
First Published:First published in ACS Applied Materials and Interfaces 9(17): 14945-14952
Publisher Policy:Reproduced under a Creative Commons license

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