Solution-processable tetrazine and oligothiophene based linear A-D-A small molecules: Synthesis, hierarchical structure and photovoltaic properties

A series of high coplanar alternative linear small molecules with acceptor-donor-acceptor (A-D-A) structure containing electron-accepting tetrazine moiety and electron-donating olighothiophenes (OTs) moiety, alkylated thiophene attached to both sides of the Tz moiety were designed and synthesized. The influences of varied oligothiophene length on small molecules' optical and electrochemical properties, crystallization, hierarchical structure in blend film with (6,6)-phenyl-C61-butyric acid methyl ester, and photovoltaic properties for the application as donor materials in organic solar cells were studied. The hierarchical structure can be tuned by changing the OTs based on the A-D-A structure, which exhibit great effect on the photovoltaic properties.