Y6 (BTP-4F) is a highly conjugated organic semiconductor. It is composed of a fused thienothienopyrrolo-thienothienoindole (TTP-TTI) core base and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) end units. These 2FIC end units are believed to promote intermolecular interactions and enhance optical absorption.
Having a A-DAD-A structure, it is electron deficient and is used in highly efficient OPV devices as a non-fullerene electron acceptor (NFA).
The absorption of Y6 has a maximum at around 810 nm and extends to 1100 nm (corresponding to the near infra-red).
Optimised photovoltaic devices using Y6 as the acceptor and PBDB-T-2F (PM6) as the polymer donor can demonstrate efficient device performance with power conversion efficiencies (PCEs) of up to 15.7%.
Device structure: ITO/PEDOT:PSS/PM6:Y6/PDINO/Al.