An effective d‐π‐a type donor material based on 4‐fluorobenzoylacetonitrile core unit for bulk heterojunction organic solar cells

In order to develop new and effective donor materials, a planar donor‐π‐acceptor (D‐π‐ A) type small organic molecule (SOM), 2‐(4‐fluorobenzoyl)‐3‐(5″‐hexyl‐[2,2′:5′,2″‐terthiophen]‐5‐yl) acrylonitrile, named as H3T‐4‐FOP, was synthesized by the reaction of 4‐fluorobenzoylacetonitrile (as acceptor unit) and hexyl terthiophene (as donor unit) derivatives. Promising optical, solubility, electronic and photovoltaic properties were observed for the H3T‐4‐FOP SOM. Significantly, the presence of 4‐fluorobenzoylacetonitrile as an acceptor unit in H3T‐4‐FOP SOM tuned the optical band gap to ~2.01 eV and procured the reasonable energy levels as highest occupied molecular orbital (HOMO) of −5.27 eV and lowest unoccupied molecular orbital (LUMO) −3.26 eV. The synthesized H3T‐4‐FOP SOM was applied as a donor material to fabricate solution‐processed bulk hetero-junction organic solar cells (BHJ‐OSCs) with an active layer of H3T‐4‐FOP: PC61BM (1:2, w/w) and was validated as having a good power conversion efficiency (PCE) of ~4.38%. Our studies clearly inspire for future designing of multifunctional groups containing the 4‐fluorobenzoylacetonitrile based SOM for high performance BHJ‐OSCs.