Conjoint use of dibenzosilole and indan-1,3-dione functionalities to prepare an efficient non-fullerene acceptor for solution-processable bulk-heterojunction solar cells

A solution-processable, non-fullerene electron acceptor, 2,2′-(((5,5-dioctyl-5H-dibenzo[b,d]silole-3,7-diyl)bis(thiophene-5,2-diyl))bis(methanylylidene))bis(1H-indene-1,3(2H)-dione) (called N5) comprised of dibenzosilole and 1,3-indanedione building blocks was designed, synthesized, and fully characterized. N5 is highly soluble in various organic solvents, has high thermal stability, and has energy levels matching those of archetypal donor poly(3-hexylthiophene). Solution-processable, bulk-heterojunction solar cells afforded promising power conversion efficiency of 2.76% when N5 was used as a non-fullerene electron acceptor along with the conventional donor polymer poly(3-hexylthiophene). As per our knowledge, the material reported herein is the first example in the literature where synchronous use of such building blocks is demonstrated in the design an efficient, non-fullerene acceptor.