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The medium band gap donor-acceptor(D-A) copolymer J61 based on bi(alkylthio-thienyl)benzodithiophene as donor unit and fluorobenzotriazole as acceptor unit and thiophene as π-bridge has demonstrated excellent photovoltaic performance as donor material in nonfullerene polymer solar cells(PSCs) with narrow bandgap n-type organic semiconductor ITIC as acceptor.For studying the effect of π-bridges on the photovoltaic performance of the D-A copolymers,here we synthesized a new D-A copolymer J61-F based on the same donor and acceptor units as J61 but with furan π-bridges instead of thiophene.J61-F possesses a deeper the highest occupied molecular orbital(HOMO) level at-5.45 eV in comparison with that(-5.32 eV) of J61.The non-fullerene PSCs based on J61-F:ITIC exhibited a maximum power conversion efficiency(PCE) of 8.24%with a higher open-circuit voltage(V_(oc)) of 0.95 V,which is benefitted from the lower-lying HOMO energy level of J61-F donor material.The results indicate that main chain engineering by changing π-bridges is another effective way to tune the electronic energy levels of the conjugated D-A copolymers for the application as donor materials in non-fullerene PSCs.
The medium band gap donor-acceptor (DA) copolymer J61 based on bi (alkylthio-thienyl) benzodithiophene as donor unit and fluorobenzotriazole as acceptor unit and thiophene as π-bridge has demonstrated excellent photovoltaic performance as donor material in nonfullerene polymer solar cells ) with narrow bandgap n-type organic semiconductor ITIC as acceptor. For studying the effect of π-bridges on the photovoltaic performance of the DA copolymers, here we synthesized a new DA copolymer J61-F based on the same donor and acceptor units as J61 but with furan π-bridges instead of thiophene. J61-F possesses a deeper into the most occupied molecular orbital (HOMO) level at-5.45 eV in comparison with that (-5.32 eV) of J61. The non-fullerene PSCs based on J61- F: ITIC exhibited a maximum power conversion efficiency (PCE) of 8.24% with a higher open-circuit voltage (V_ (oc)) of 0.95 V, which is benefitted from the lower-lying HOMO energy level of J61-F donor material. The results indicating that main chain engineering by changing π-bridges is another effective way to tune the electronic energy levels of the conjugated D-A copolymers for the application as donor materials in non-fullerene PSCs.