Comparison of two side-chain design strategies for indacenodithienothiophene–naphthalene diimide polymer photovoltaic acceptors prepared by direct (hetero)arylation polycondensation

Two new indacenodithienothiophene–naphthalene diimide polymer acceptors PIN-1 and PIN-2 are rationally designed by two side-chain design strategies (SE-2 and SE-3) and are synthesized by the direct (hetero)arylation polycondensation (DHAP) method. Their physicochemical properties are investigated. Both polymers have similar narrow bandgaps and electron energy levels, which match well with the wide bandgap polymer donor PBZ-C6. The all-polymer solar cells (all-PSCs) based on the optimized PBZ-C6/PIN-1 blend and the PBZ-C6/PIN-2 blend display power conversion efficiencies of 5.81% and 5.00%, respectively. The results indicate that SE-2 and SE-3 are two promising side-chain design strategies and DHAP is an alternative method for obtaining efficient naphthalene diimide polymer acceptors for all-PSCs.