ИСТИНА

The latest advances in organic photovoltaics are amazing [1]. A large part of this progress can be attributed to the development of new light-absorbing materials – non-fullerene acceptors. Developments of donor and acceptor materials have brought tandem OSCs, which afforded PCEs over 20% [2]. However, one of the problems with such NFAs is their complex molecular structure, requiring many synthetic steps, which increases cost and scalability issues. Moreover, the development of simpler chemical structures of similar push-pull annulated compounds and the search for molecular tools to fine-tune their optoelectronic properties remain highly relevant tasks for further practical applications [3]. In the course of this work, new non-fullerene acceptors based on thieno[3,2-b]thieno[2',3':4,5]pyrrolo[2,3-f]indole moiety (TPIIC) [4] and based on thieno[2',3':4,5]thieno[3,2-b]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]indole moiety (Y-series-like) [5] were synthesized to study their thermal stability, aggregate state, phase behavior, optical, electrochemical and photovoltaic properties. Ternary device, based on mix of PM6:Y6:TPIIC, exhibited a superior photovoltaic function with a PCE of 17.7%. Y-series-like compounds form a monoclinic crystal lattice compared to that of their analogues Y5 and Y6, which may be favorable for anisotropic charge conductivity; however, devices based on them have demonstrated low efficiency of converting solar energy into electrical energy. This work was supported by the Russian Science Foundation (grant № 21-43-00051).