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.