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Abstract Boron dipyrromethene (BODIPY) derivatives have good optoelectronic properties and thermal stability. However, it is rarely for such materials to use in bulk heterojunction (BHJ) organic solar cell. In this study, a variety of donor-acceptor (D-A) type boron dipyrromethene (BODIPY) based dyes were designed and synthesized for polymer solar cells (PSCs), namely BDH1-4. Thermal stability, photochemical properties, charge transport and BHJ morphology were investigated to elucidate factors affecting the photovoltaic performance in this class of polymers. These BDHs exhibit fine solubility in conventional solvents, good thermal stability, excellent panchromatic absorption in solution and in film. Furthermore, the absorption wavelength of BDH1-4 covers full color absorption in the range of 300–800 nm and has a relatively low HOMO level from −5.01 to −5.66 eV. Among them, BDH4 / PC 71 BM based PSCs exhibit highest power conversion efficiency (PCE) of 3.69% with a Jsc of 9.92 mA cm−2, a Voc of 0.63 V and a FF of 59.1%. Graphical abstract Four D-A type BODIPY based dyes were designed and synthesized for polymer solar cells (PSCs). All these polymers show appealing photovoltaic performance. Among them, BDH4/PC 71 BM based PSC exhibit not only good photoelectric characteristic but also good hole mobility and surface morphology relative to the other counterparts and thus pronounce to a higher PCE of 3.69% with a Jsc of 9.92 mA cm−2 and a FF of 59.1%. Image 1 Highlights • A series of novel D-A type dyes based on BODIPY were synthesized for PSCs. • Polymer BDH4 exhibited the highest PCE value of 3.69% with PC 71 BM. • Several factors influencing the efficiency of PSCs were demonstrated. [ABSTRACT FROM AUTHOR]

Three BT-based polymers were built through effective side-chain chlorination strategies and thiophene-induced approaches. The devices based on polymer delivered the best efficiency of 5.73 %. • Polymers were built through chlorination and thiophene-induced approachs. • The efficiency of device is improved. • PBDBT-1 gave the best device efficiency of 5.73 %. Three novel polymers with D-A (π)- BT backbone, PBDBT-0 , PBDBT-1, and PBDBT-2 , were built through effective side-chain chlorination strategies and thiophene-induced approaches. Meanwhile, the effect of different thiophene numbers was studied. As expected, all of the chlorinated polymers showed low HOMO levels. The introduction of the thiophene unit improved the solubility of the polymer and slightly adjusted the energy level of the molecule. Furthermore, polymers as donors and PC 71 BM as acceptors are used to construct organic solar cell devices. The devices based on polymer PBDBT-1 with one thiophene unit delivered the best efficiency of 5.73 % with an open-circuit voltage of 0.85 V, a short-circuit current density of 13.07 mA cm−2 and a fill factor of 51.6 %, which is superior to that of PBDBT-0 and PBDBT-2. [ABSTRACT FROM AUTHOR]