Department of Physics
We report our effort to unravel the origin of efficient operation of nonfullerene organic solar cells (OSCs), based on a poly[4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)](PTB7-Th):3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno [1,2-b:5,6-b′]dithiophene (ITIC) blend system. The effects of buildup of space charges, charge extraction, and bimolecular recombination processes on the performance and the stability of PTB7-Th:ITIC-based regular and reverse configuration OSCs are analyzed. It is found that the high-performing inverted PTB7-Th:ITIC OSCs benefit from the combined effects of (1) suppression of bimolecular recombination enabled by an augmented effective internal electric field and (2) improvement of charge extraction by avoiding the holes passing through ITIC-rich region, which would otherwise occur in a regular configuration cell. The inverted PTB7-Th:ITIC OSCs possess a significant improvement in the cell stability and a high power conversion efficiency of ∼8.0%, which is > 29% higher than that of an optimized regular configuration control cell (6.1%).
Source Publication Title
Journal of Physical Chemistry Letters
American Chemical Society
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry Letters, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.jpclett.7b02308
This work was financially supported by the Research Grants Council of Hong Kong Special Administrative Region, China; General Research Fund (12303114, 12302817); Hong Kong Baptist University Interinstitutional Collaborative Research Scheme (RC-ICRS/15-16/04); and Shenzhen Peacock Plan (KQTD20140630110339343).
Link to Publisher's Edition
Wang, Y., Wu, B., Wu, Z., Lan, Z., Li, Y., Zhang, M., & Zhu, F. (2017). Origin of efficient inverted nonfullerene organic solar cells: Enhancement of charge extraction and suppression of bimolecular recombination enabled by augmented internal electric field. Journal of Physical Chemistry Letters, 8 (21), 5264-5271. https://doi.org/10.1021/acs.jpclett.7b02308
Additional FilesJA-5052-29419_suppl.pdf (516 kB)