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arXiv · 2104.09687

Quantitative insights into the phase behaviour and miscibility of organic photovoltaic active layers from the perspective of neutron spectroscopy

Mohamed Zbiri·Peter A. Finn·Christian B. Nielsen·Anne A. Y. Guilbert
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Abstract

We present a neutron spectroscopy based method to study quantitatively the partial miscibility and phase behaviour of an organic photovoltaic active layer made of conjugated polymer:small molecule blends, presently illustrated with the regio-random poly(3-hexylthiophene-2,5-diyl) and fullerene [6,6]-Phenyl C$_{61}$ butyric acid methyl ester (RRa-P3HT:PCBM) system. We perform both inelastic neutron scattering and quasi-elastic neutron scattering measurements to study the structural dynamics of blends of different compositions enabling us to resolve the phase behaviour. The difference of neutron cross sections between RRa-P3HT and PCBM, and the use of deuteration technique, offer a unique opportunity to probe the miscibility limit of fullerene in the amorphous polymer-rich phase and to tune the contrast between the polymer and the fullerene phases, respectively. Therefore, the proposed approach should be universal and relevant to study new non-fullerene acceptors that are closely related - in terms of chemical structures - to the polymer, where other conventional imaging and spectroscopic techniques present a poor contrast between the blend components.

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Mohamed Zbiri, Peter A. Finn, Christian B. Nielsen, Anne A. Y. Guilbert. 2021-04-19. Quantitative insights into the phase behaviour and miscibility of organic photovoltaic active layers from the perspective of neutron spectroscopy. https://doi.org/10.1039/d1tc01813b

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