Non-fullerene Acceptors with a Thieno[3,4-c]pyrrole-4,6-dione (TPD) Core for Efficient Organic Solar Cells

To achieve the red-shifted absorptions and appropriate energy levels of A-D-A type non-fullerene acceptors (NFAs), in this work, we design and synthesize two new NFAs, named TPDCIC and TPDCNC, whose electron-donating (D) unit is constructed by a thieno[3,4-c]pyrrole-4,6-dione (TPD) core attached to two cyclopentadithiophene (CPDT) moieties at both sides, and the electron-accepting (A) end-groups are 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (IC) and 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b] naphthalen-1-ylidene)malononitrile (NC), respectively. Benefiting from TPD core, which easily forms quinoid structure and OMIDLINE HORIZONTAL ELLIPSISH or OMIDLINE HORIZONTAL ELLIPSISS intramolecular noncovalent interactions, TPDCIC and TPDCNC show more delocalization of pi-electrons and perfect planar molecular geometries, giving the absorption ranges extended to 822 and 852 nm, respectively. Furthermore, the highest occupied molecular orbital (HOMO) levels of TPDCIC and TPDCNC remain relatively low-lying due to the electronegativity of the carbonyl groups on TPD core. Considering that the absorptions and energy levels of the two NFAs match well with those of a widely used polymer donor, PBDB-T, we fabricate two kinds of organic solar cells (OSCs) based on the PBDB-T:TPDCIC and PBDB-T:TPDCNC blended films, respectively. Through a series of optimizations, the TPDCIC-based devices yield an impressing power conversion efficiency (PCE) of 10.12% with a large short-circuit current density (J(SC)) of 18.16 mA center dot cm(-2), and the TPDCNC-based ones exhibit a comparable PCE of 9.80% with a J(SC) of 17.40 mA center dot cm(-2). Our work is the first report of the TPD-core-based A-D-A type NFAs, providing a good reference for the molecular design of high-performance NFAs.