Effect of non-covalent interactions on molecular stacking and photovoltaic properties in organic photovoltaics

Abstract

The conjugated structures of donor–acceptor (D–A) type with sulfur (S), nitrogen (N) and oxygen (O) atoms aid to close packing each other in the backbone by non-covalent interactions. Furthermore, non-covalent interactions are exerted three dimensionally and affect various properties. To know this effects, we introduced different S, N and O contents as benzothiadiazole (BT) and dithienophenazine (DTPz, up or down direction of S) units on each polymer backbone. Among the three polymers, P2 with up direction of S showed an open-circuit voltage (Voc) of 0.90V, fill factor (FF) of 54.7% and reached best power conversion efficiency (PCE) of 4.8%.