Effect of perfluorination on the charge-transport properties of organic semiconductors: density functional theory study of perfluorinated pentacene and sexithiophene

Density functional theory calculations were carried out to investigate the effect of perfluorination on the reorganization energy (λ) of charge-transport process. Fluorine substitution was found to increase the reorganization energy, disadvantageous for charge-transport. The enhancement of λ is attributed to additional contributions from the stretching of C–F bonds. On the other hand, perfluorination tends to increase electron affinity and ionization potential of compounds, favoring for electron– rather than hole–transport in viewpoints of thermodynamic stability and injection barrier of charge. Based on these findings, valuable guidelines for the design of n-type materials with improved performance were proposed.