Can, AyseChoi, Gi-SeokOzdemir, ResulPark, SoyoonPark, Jin SuLee, YongchulUsta, Hakan2025-09-252025-09-2520222637-6105https://doi.org/10.1021/acsapm.1c01856https://hdl.handle.net/20.500.12573/4182Kim, Choongik/0000-0001-7494-0677; Can, Ayse/0000-0003-3965-4151; Park, Jin Su/0009-0005-9325-9541; Mutlugun, Evren/0000-0003-3715-5594; Ozdemir, Resul/0000-0002-7957-110X;The realization of pi-deficient acceptors and their donor-acceptor copolymers has become a key research focus for the realization of versatile organic optoelectronic materials and devices. Herein, we demonstrate the theoretical design, synthesis, and physicochemical/optoelectronic characterization of two meso-pi-extended/deficient BODIPY building blocks (2OD-T2BDY and 2OD-TTzBDY) and a library of donor-acceptor copolymers with low band gap (E-g = 1.30-1.35 eV) based on these building blocks. These building blocks, to the best of our knowledge, are the first examples of BODIPYs with meso-pi-extension. A library of BODIPY building blocks with varied meso units/substituents is studied to reveal the meso effects on the semiconducting BODIPY's optoelectronic properties. The building blocks showed favorable pi-acceptor electronic/structural properties with meso-pi-delocalized and stabilized LUMOs (ca. -3.6 eV) and large ground-state dipole moments of 4.9-5.5 D. Consistent with the theoretical/experimental pi-electronic structures, all copolymers functioned as p-type semiconductors in field-effect transistors and as donor materials in the bulk heterojunction organic photovoltaics. Power conversion efficiencies of up to 4.4% with a short-circuit current of 12.07 mA cm(-2) were achieved. This study demonstrates a unique meso-pi-extension strategy to realize BODIPYs with favorable pi-acceptor properties, and our findings could open up future materials design avenues in various organic optoelectronic applications.eninfo:eu-repo/semantics/openAccessConjugated PolymersBODIPYOrganic Solar CellsOrganic SemiconductorsLumoArticle10.1021/acsapm.1c018562-s2.0-85125292640