New Medium Band Gap Nonfullerene Acceptors Based on 4H- Dithieno[3,2 b:2′,3′-d]Pyrrole with Different Aliphatic Side Chains for Organic Solar CellsстатьяИсследовательская статья
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Аннотация:ABSTRACT: The alkyl side chains in the core in the A-D-Anonfused ring nonfullerene acceptors significantly influence thephotocurrent generation and overall power conversion efficiency(PCE) in the organic solar cells (OSCs). Here in, we have designedtwo A-D-π-D-A unfused NFAs featuring the identical central π-ethynylene linker and BTA terminal acceptor (A) unit but utilizingdithiophenepyrrole (DTP) with different side chains, i.e.,octyldodecyl (OD) (NFA-8) and 2-hexyldecyl (HD) (NFA-9).The investigations were focused on their optical and electro-chemical properties. When paired with PBDB-T as the donor, theOSCs utilizing PBDB-T:NFA-8 and PBDB-T:NFA-9 attained PCEof about 9.95 and 13.90%, respectively. The improved PCE forNFA-9-based OSCs is primarily attributed to the increased short circuit current and fill factor (FF). The higher short circuit currentand FF in the NFA-9-based OSCs could be attributed to the prolonged exciton lifetime for NFA-9, effective separation of excitoninto free charge carriers, and their successive collection in the NFA-9-based OSCs. Due to the absorption spectra of these bulk heterojunction active layers being restricted to 810 nm, these NFAs can have a potential for indoor OSCs and guest acceptors for ternary and front subcells for tandem OSCs.
