Dithieno[2,3‐e:3′,2′‐g]isoindole‐7,9(8H)‐Dione and Dithieno[3′,2′:5,6;2″,3″:7,8]naphtho[2,3‐d]imidazol‐9(10H)‐One‐Based Wide Bandgap Copolymer for Efficient Polymer Solar Cells

• Published in: Energy technology (Weinheim, Germany) Germany), 2023-02, Vol.11 (2), p.n/a
• Main Authors: Keshtov, Mukhamed L., Shikin, Dimitry Y., Khokhlov, Alexei R., Ostapov, Ilya E., Alekseev, Vladimir G., Singh, Manish K., Sharma, Ganesh D.
• Format: Article
• Language: English
• Subjects: D–A copolymers; fused-ring acceptor units; nanoscale morphology; polymer solar cells; power conversion efficiency
• ISSN: 2194-4288; 2194-4296
• DOI: 10.1002/ente.202201211

Two donor–acceptor (D–A) backbone copolymers with different fused ring acceptors, i.e., dithieno [2,3‐e:3′,2′‐g]isoindole‐7,9(8 H)‐dione (DTID) and dithieno[3′,2′:5,6;2″,3″:7,8]naphtho[2,3‐d]imidazol‐9(10 H)‐one (DTNID) and same benzo[1,2‐b:4,5‐b′]dithiophene with alkylated aromatic side as side chains (BDTT) donor, denoted as P133 and P135 are synthesized and used as donor along with narrow bandgap nonfullerene Y6 acceptor for the preparation of polymer solar cells (PSCs). The dielectric constant of P135:Y6 is higher than that of P133:Y6 due to the strong electron deficient ability of DTNID compared to DTID, which fostered exciton dissociation and charge transport, constrained charge recombination, and ultimately boosted the power conversion efficiency of P135:Y6 to 15.11%, which is higher than P133:Y6 (10.24%). Therefore, these investigations confirm the pronounced potential of fused ring DTNID as an acceptor unit for emerging D–A copolymers for PSCs with high efficiency. The power conversion efficiency for P135:Y6 (15.11%) is higher than that for P133:Y6 (10.24%), which is attributed to the efficient charge separation and transport due to the high dielectric constant of the former blend, owing to the reduced exciton binding energy due to the two polar carbonyl groups in P135 donor–acceptor copolymer.