An Electron-Deficient Small Molecule Accessible from Sustainable Synthesis and Building Blocks for Use as a Fullerene Alternative in Organic Photovoltaics

An electron‐deficient small molecule accessible from sustainable isoindigo and phthalimide building blocks was synthesized via optimized synthetic procedures that incorporate microwave‐assisted synthesis and a heterogeneous catalyst for Suzuki coupling, and direct heteroarylation carbon–carbon bond forming reactions. The material was designed as a non‐fullerene acceptor with the help of DFT calculations and characterized by optical, electronic, and thermal analysis. Further investigation of the material revealed a differing solid‐state morphology with the use of three well‐known processing conditions: thermal annealing, solvent vapor annealing and small volume fractions of 1,8‐diiodooctane (DIO) additive. These unique morphologies persist in the active layer blends and have demonstrated a distinct influence on device performance. Organic photovoltaic–bulk heterojunction (OPV‐BHJ) devices show an inherently high open circuit voltage (Voc) with the best power conversion efficiency (PCE) cells reaching 1.0 V with 0.4 v/v % DIO as a processing additive. A blueprint for the sustainable synthesis of electron‐accepting small molecules as fullerene alternatives in organic photovoltaics is presented.