BTP-eC9 is a family member of the Y series of n-type non-fullerene semiconducting acceptors. It has been proven that these NFAs can achieve high device performance in non-fullerene polymer solar cells (NF-PSCs).
With a fused thienothienopyrrolo-thienothienoindole (TTP-TTI) core, BTP-eC9 is a modified version of Y7 but with better solubility. Comparing to Y6, chlorination at the peripheral end-groups can efficiently lower HOMO/LUMO energy levels. C–Cl bond also has a large dipole moment, expanding the absorption range further to near infrared (NIR) region.
A device efficiency approaching 18% has been reported using BTP-eC9 as the electron acceptor and PBDB-T-2F (PM6) as electron donor in single junction organic photovoltaic cells.
Device structure: ITO/PEDOT:PSS/PBDB-T-2F:BTP-eC9 (1:1.2)/PFN-Br/Al