Study of the influence of functionalization on the reorganization energy of naphthalene using DFT

Abstract

In this work, a number of naphthalene derivatives have been constructing by including various functional groups, i.e., F, Cl, or N atoms or NO2 or CN groups, and investigated theoretically by using the B3LYP/6-31G∗∗ method with the aim of studying their electronic and charge transport properties. Special attention is paid to the reorganization energy of the charge transport process, as well as the adiabatic electron affinities (EA), the 1st ionization potential (IP), the HOMO and LUMO orbital energies, and the HOMO-LUMO energy gap. We find that the reorganization energies (λ+ and λ−) in some cases are higher compared to those of the unsubstituted system, whereas the calculated λ values for Cl-functionalized naphthalene are significantly smaller than those of the F-functionalized system. The enhancement of λ is attributed to additional contributions from the CR bonds (R=F, Cl, CN, NO2, and/or N). On the other hand, functionalization of naphthalene tends to increase the electron affinity and the ionization potential. The electron-withdrawing groups were found to increase the reorganization energy and decrease the HOMO-LUMO gap. Based on our findings, we suggest that functionalization can be used as valuable techniques to control the electronic properties of these n-type and p-type semiconductor materials.