Star-shaped electron acceptors containing a truxene core for non-fullerene solar cells

Abstract

Abstract A series of new electron acceptors containing a truxene core with intense optical absorption were synthesized and used for non-fullerene organic solar cells. Due to the weak electron-donating characteristic of truxene core and thereby weak intramolecular charge transfer interaction from electron-donating core to electron-withdrawing end groups, the resulting new acceptors show relatively wide optical band-gap and high-lying lowest unoccupied molecular orbitals (LUMOs), which consequently lead to complementary light spectra with narrow band-gap donor polymers and high open circuit voltage (Voc) in solar cells. Particularly, Tr(Hex)6-3BR, a star-shaped planar acceptor, produced the highest power conversion efficiency of 2.1% with a high Voc of 1.02 V when blended with PTB7-Th.