Mono-cyclopropanated C120O was prepared to obtain soluble, longish electron acceptor opening the possibility to make organic photoactive layers of supra-molecular and anisotropic order. The C120O derivative was characterized by UV-vis spectroscopy, cyclic voltammetry, and thermogravimetric analyses, and applied as electron acceptor in a bulk-heterojunction polymer solar cell. The C120O derivative is appraised to be a valuable electron acceptor.