A new synthetic route, to prepare an alkylated indacenodithieno[3,2-b]thiophene-based nonfullerene acceptor (C8-ITIC), is reported. Compared to the reported ITIC with phenylalkyl side chains, the new acceptor C8-ITIC exhibits a reduction in the optical band gap, higher absorptivity, and an increased propensity to crystallize. Accordingly, blends with the donor polymer PBDB-T exhibit a power conversion efficiency (PCE) up to 12.4%. Further improvements in efficiency are found upon backbone fluorination of the donor polymer to afford the novel material PFBDB-T. The resulting blend with C8-ITIC shows an impressive PCE up to 13.2% as a result of the higher open-circuit voltage. Electroluminescence studies demonstrate that backbone fluorination reduces the energy loss of the blends, with PFBDB-T/C8-ITIC-based cells exhibiting a small energy loss of 0.6 eV combined with a high JSC of 19.6 mA cm-2 .
KAUST Repository Item: Exported on 2023-01-09
Acknowledgements: The authors thank the British Council (337323) EPSRC (EP/L016702/1, EP/M025020/1, EP/P02484X/1), the Daphne Jackson Trust and the Australian Research Council (DP170102145) for the financial support. This work was performed in part on the SAXS/WAXS beamline at the Australian Synchrotron, part of ANSTO.
- Mechanics of Materials
- Materials Science(all)
- Mechanical Engineering