Trends in Conjugated Chalcogenophenes: A Theoretical Study

Heavy atom substitution in chalcogenophenes is a versatile strategy for tailoring and ultimately improving conjugated polymer properties. While thiophene monomers are commonly implemented in polymer designs, relatively little is known regarding the molecular properties of the heavier chalcogenophenes. Herein, we use density functional theory (DFT) calculations to examine how group 16 heteroatoms, including the radioactive polonium, affect polychalcogenophene properties including bond length, chain twisting, aromaticity, and optical properties. Heavier chalcogenophenes are more quinoidal in character and consequently have reduced band gaps and larger degrees of planarity. We consider both the neutral and radical cationic species. Upon p‐type doping, bond length rearrangement is indicative of a more delocalized electronic structure, which combined with optical calculations is consistent with the polaron‐model of charge storage on conjugated polymer chains. A better understanding of the properties of these materials at their molecular levels will inevitably be useful in material design as the polymer community continues to explore more main group containing polymers to tackle issues in electronic devices. Density functional theory (DFT) calculations are utilized to assess polychalcogenophene properties with different chalcogen substitutions, including polonium, for both neutral and cationic species. Studied properties include bond length, chain twisting, aromaticity and optical properties. Heavier heteroatoms reduce band gaps and cause ring distortion. The inter‐ring bond indicates quinoidal character. Furans are consistent outliers. Doping causes diminishment of bond‐length alternation and further reduction of band gaps.