Ternary polymerization strategy to approach 12% efficiency in all-polymer solar cells processed by green solvent and additive

The terpolymers based on indacenodithiophene dicyanindenone derivative, named as PTer-N10, PTer-N25 and PTer-N50, were designed and synthesized by incorporating naphthalenediimide derivative with 10%, 25% and 50% molar ratios as another electron-withdrawing unit, respectively. These terpolymers were used as the acceptors to prepare all-polymer solar cells (all-PSCs) with o-xylene as the solvent and 2-methylnaphthalene as the additive without any annealing treatment, which showed high power conversion efficiency (PCE). The terpolymer PTer-N25 possesses the highest light harvest, the best morphology, the highest and most balanced charge mobilities in blend film, so the all-PSC based on PM6: PTer-N25 achieved the highest PCE of 11.94%. This study indicates that ternary polymerization is an efficient strategy to obtain green-solvent processing polymeric acceptors, which can achieve high-performance all-PSCs.