Résumé
Phosphonium-based polythiophene conjugated polyelectrolytes (CPEs) with three different counterions (dodecylsulfate, octylsulfate and perfluorooctane sulfonate) are synthesized to determine how the nature of the counterion affects the thermal properties, the self-assembly in thin films and the performance as the cathode interfacial layer in polymer solar cells (PSCs). The counterion has a significant effect on the thermal properties of the CPEs, affecting both their glass transition and crystalline behaviour. Grazing-incidence wide-angle X-ray scattering studies also indicate that changing the nature of the counterion influences the microstructural organization in thin films (face-onversusedge-on orientation). The affinity of the CPEs with the underlying photoactive layer in PSCs is highly correlated with the counterion species. Finally, in addition to an increase of the power conversion efficiency ofca15% when using these CPEs as cathode interfacial layers in PSCs, a higher device stability is noted, compared to a reference device with a calcium interlayer. (c) 2020 Society of Industrial Chemistry
This work was supported by the CNRS and the Universite de Montpellier. This work was also supported in part by the Science Foundation Ireland under grant no. 12/IP/1608. Research in Mons is supported by FNRS-FRFC (2Dto3D project - EOS programme) and Region Wallonne (OPTI2MAT excellence programme). The University of Mons and Hasselt University co-authors are grateful for financial support by the Science Policy Office of the Belgian Federal Government (BELSPO; PAI/IAP 7/05). JK is a postdoctoral fellow of the Research Foundation - Flanders (FWO Vlaanderen). NVdB thanks the Vrije Universiteit Brussel for a post-doctoral grant. The HINT COST action MP1202 and French-Irish programme 'Hubert Curien Ulysses' (31998ZF) are also acknowledged for support. This research has also been supported by the European Commission under the 7th Framework Programme through the 'Research Infrastructures' action of the 'Capacities' programme (contract no. CP-CSA_INFRA-2008-1.1.1 Number 226507-NM13). We further thank the Diamond Light Source for beamtime at the I07 beamline (experiment SI13868) and TA Instruments for the RHC equipment.
Clement, S (corresponding author), Univ Montpellier, ENSCM, CNRS, ICGM, Montpellier, France.
sebastien.clement1@umontpellier.fr