Abstract
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.
Original language | English (US) |
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Article number | 1705209 |
Journal | Advanced Materials |
Volume | 30 |
Issue number | 8 |
DOIs | |
State | Published - Feb 22 2018 |
Keywords
- conjugated polymers
- crystal engineering
- nonfullerene acceptors
- organic solar cells
ASJC Scopus subject areas
- General Materials Science
- Mechanics of Materials
- Mechanical Engineering