Efficient organic solar cells with benzo[b]phenazine-core acceptors: insights into the effects of halogenation.

A series of new small-molecule acceptors—NA9, NA10, and NA11—based on benzo[b]phenazine are synthesized. The chlorinated NA10 and brominated NA11 exhibit improved molecular packing and enhanced charge transport, resulting in higher power conversion efficiencies (PCEs) of 15.65% and 16.64%, respectively, compared to 11.66% for the non-halogenated NA9. These results underscore the great potential of peripheral halogenation particularly bromination, in achieving high-performance OSCs. [ABSTRACT FROM AUTHOR]