Herein we present the design, synthesis and characterization of two novel, naphthalene diimide (NDI) core-based non-fullerene acceptors, N5 and N6, comprising respectively 2-methoxyethyl-2-cyanoacetate and cyanopyridone acceptor functionalities at the terminals. The influence of terminal units on optoelectronic and photovoltaic properties was studied. The target chromophore bearing cyanopyridone acceptor units (N6) afforded a power conversion efficiency of 6.10% when paired with the conventional donor polymer poly(3-hexylthiophene), a result that is the highest for the NDI core-based non-fullerene acceptors.