Alkyl side-chain and fluorination engineering in the indeno[1,2-b]fluorene-based small-molecule acceptors for efficient non-fullerene organic solar cells

Four new small-molecule acceptors based on indeno[1,2-b]fluorene were designed and synthesized. The impact of alkyl chain of the thiophene spacer and fluorination of end-capping groups on the molecular band gaps, energy levels and photovoltaic performance was systematically investigated.262