Y7 (CAS number 2414918-25-3), also known as BTP-4Cl, is the chlorinated version of Y6 (BTP-4F). It has an absorption range that extends to the near infrared (NIR) and has demonstrated a power conversion efficiency (PCE) up to 15.7% with PBDB-T-2F (PM6) as the polymer donor.

Like Y6, Y7 is a highly conjugated organic semiconductor and is composed of a fused thienothienopyrrolo-thienothienoindole (TTP-TTI) core base and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2ClIC) end units. Y7 has an A-DAD-A structure and is therefore electron deficient and hence suitable for use as a n-type non-fullerene electron acceptor (NFA) in OPV devices.

Compared to Y6, the chlorinated acceptor Y7 shows a redshift of about 20 nm in optical absorption and about 100 meV downshift in the LUMO level. Device film containing Y7 has a higher electroluminescence quantum efficiency (EQE = 3.47 × 10-4) than that of Y6 (1.40 × 10-4) with reduced non-radiative energy loss of ~ 24 meV. This reduced non-radiative energy loss yields a higher VOC of 0.867 V compared with that of the Y6 based device (0.834 V).

Record PCEs of 16.5% and 15.3% for OPV cells with 0.09 and 1 cm2 active areas were achieved when PBDB-T-2F (PM6) was used as the polymer donor and Y7 as the acceptor with the following device structure.

Device structure: ITO/ZnO/PM6:Y7/MoO3/Al.

Chemical Structure

General Information