Alkynylated acenothiadiazoles and N-heteroacenes: synthesis, functionalization, and study of the optical properties for optoelectronic and sensory materials

Abstract

For organic electronic device applications materials are needed which display good charge carrier mobility, good processability, and stability towards oxygen and moisture. Alkynylated N-Heteroacenes fulfill many of these requirements. Substitution with alkyne groups as well as the introduction of the pyrazine subunit both inhibits oxidative degradation at sensitive position in the molecules. Additionally the trialkylsilylethynyl group aides in directing the packing motif as well as vastly increases the solubility over unsubstituted analogues. A requisite precursor in the synthesis of alkynylated N-heteroacenes is alkynylated acenothiadiazoles. These thiadiazoles display interesting photophysical properties and can be functionalized to produce a wide range of properties in closely related materials. The acenothiadiazoles themselves have potential applications as an N-type semiconductor. Optical gaps and calculated HOMO-LUMO gaps show that these molecules, when compared to known N-type materials, should be easily injected with electrons. Additionally the crystal packing of these compounds shows favorable π-orbital overlap which should provide excellent charge carrier mobilities.