Impact of structural polymorphs on charge collection and non-geminate recombination in organic photovoltaic devices
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Accepted version
Author(s)
Type
Journal Article
Abstract
The formation of different types of structural polymorphs of poly(3-hexyl-thiophene) (P3HT) affects the performance of organic photovoltaic (OPV) devices that use thermally-annealed P3HT:PCBM[60] blend films as photoactive layer. Here it is demonstrated that, when densely-packed and non-densely packed P3HT polymorphs co-exist in the P3HT:PCBM[60] layer, non-geminate charge recombination is fast; however, in a device non-geminate recombination is effectively overruled by efficient and fast charge carrier extraction. In stark contrast, when only a less-densely packed P3HT polymorph is present in the blend, non-geminate charge recombination losses are less pronounced, and the charge carrier extraction efficiency is lower. The antagonistic non-geminate charge recombination and charge carrier extraction processes in these systems are monitored by time-delayed-collection field (TDCF) and ultrafast transient absorption (TA) experiments. Furthermore, resonance Raman spectroscopy reveals that in the absence of the densely-packed P3HT polymorph, the energetic disorder present in the P3HT:PCBM[60] blend is higher. High-resolution atomic force microscopy imaging further identifies pronounced differences in the layer morphology when the polymorph distribution varies between unimodal and bimodal. These results indicate that less-densely packed P3HT polymorphs increase disorder and impede charge collection, leading to a reduction of the device fill factor.
Date Issued
2018-12-27
Date Acceptance
2018-12-01
Citation
The Journal of Physical Chemistry C, 2018, 122 (51), pp.29141-29149
ISSN
1932-7447
Publisher
American Chemical Society (ACS)
Start Page
29141
End Page
29149
Journal / Book Title
The Journal of Physical Chemistry C
Volume
122
Issue
51
Copyright Statement
© 2018 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/acs.jpcc.8b09825
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/L016702/1
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Chemistry
Science & Technology - Other Topics
Materials Science
MORPHOLOGY EVOLUTION
SOLAR-CELLS
POLYMER
PERFORMANCE
GENERATION
TRANSPORT
SEPARATION
DIFFUSION
09 Engineering
03 Chemical Sciences
10 Technology
Physical Chemistry
Publication Status
Published
Article Number
acs.jpcc.8b09825
Date Publish Online
2018-12-04