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Authors
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Matsidik, R.; Komber, H.; Burkhard, P.; Beer, D.; Deibel, C.; Sommer, M.
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Title
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Acceptor end-functionalization of naphthalenediimide bithiophene oligomers
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Date
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09.11.2024
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Number
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0
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Abstract
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Oligomeric materials combine advantageous properties of both their small molecule and polymeric counterparts. Utilizing oligomers as non-fullerene acceptors (NFAs) has been shown to be extremely useful for the development of organic solar cells with high efficiency, reproducible performance and long-term stability. Here we report on two series of synthetically simple acceptor-terminated oligomers A−T2-(NDI−T2)n-A with naphthalene diimide (NDI) and bithiophene (T2) cores up to the trimer (n =1,2,3). Termination of the oligomers is done using the strong acceptors (A) dicyanomethylene-indanone (IC) and rhodanine (RD). Upon acceptor termination in the presence of piperidine (pip) as base, oligomers with pip-substituted tricyclic end groups are obtained in high yield. We investigate the effect of oligomer length and acceptor end group on opto-electronic properties and crystallinity. Both IC- and RD-termination increase electron affinity compared to the parent, non-functionalized cores. UV-vis absorption in solution slightly redshifts as the chain length increases without showing a distinct aggregation. Asymmetric termination with hexylphenyl-substituted indacenodithiophene (IDT) and IC is also possible. All symmetric oligomers show a strong tendency for crystallization, with the oligomer having the tricyclic end group exhibiting the highest melting enthalpy and temperature. The asymmetric IDT−T2-NDI−T2-IC oligomer is amorphous.
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Publisher
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Wiley
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Wikidata
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Citation
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European Journal of Organic Chemistry 27 (2024) e202400751
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DOI
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https://doi.org/10.1002/ejoc.202400751
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