The increasing costs of inorganic semiconducting components in electronic devices have driven the search for cheaper substitutes. Organic molecular crystals are one group of inexpensive materials which have the potential to replace inorganic semiconductors. One important property to consider when investigating potential organic semiconductor candidates is charge carrier mobility (μmob). Since this property is difficult to calculate using conventional computational chemistry approaches, properties which are correlated to μmob are calculated instead. Such properties include the intermolecular orbital overlap integral (Hab), valence and conduction band dispersion, crystalline polarizability, and the intermolecular crystal energy framework. In this study, the relationship between the crystal packing of all homo-halogenated benzene crystals found in the Cambridge Crystal Structure Database (CSD) and the above electronic properties was examined as halogen bonding is known to perturb the electronic properties of organic materials. It was found that homo-halogenated benzene crystals which had highly symmetric halogenation patterns had identical packing and energy frameworks regardless of the halogen species. On the other hand, it was found that crystals with asymmetric molecular components had different packing patterns dictated by halogen bonding trends associated with the attached halogen species. Packing arrangements containing the most π-π interactions between the benzene rings had some of the highest band dispersion and crystalline energy framework values. Generally, it was found that symmetrical species had smaller band gap values compared to asymmetrical species. In addition, it was found that symmetrical species with larger halogens typically had higher energy framework values.

Effects of the crystal packing of homo-halogenated benzenes on their electronic properties

2019 Fall National Meeting

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