Research Article

The impact of functionalization of organic semiconductors by electron donating groups on the reorganization energy

¹ National Center for Research, Institute of Engineering Research and Material Technology, P.O. Box 2404, Khartoum, Sudan
² Department of Chemistry, Faculty of Science, University of Khartoum, P.O. Box 321, Khartoum, Sudan
³ Physical and Theoretical Chemistry, University of Saarland, 66123 Saarbrücken, Germany
⁴ School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P.R. China

^a e-mail: sahar.abdalla@uofk.edu

Received: 14 January 2019
Received in final form: 2 April 2019
Published online: 18 June 2019

Abstract

The electronic and charge-transport properties of three organic semiconductor materials were theoretically investigated using density functional (DFT) theory based on the Marcus–Hush theory. The functionalization of 7,7,8,8-Tetracyanoquinodimethane, 1,4,5,8-Naphthalenetetracarboxylic dianhydride, and Perylene-3,4,9,10-tetracarboxylic dianhydride by electron donating groups (R = CH₃, OCH₃, and OH) increases the reorganization energies for hole and electron transfer (λ⁺ and λ⁻) due to additional contributions from the C–R bonds. Simultaneously, the electron affinity and ionization potential are reduced, except for the electron affinity of 4OH-TCNQ. The HOMO–LUMO energy gaps are also studied. Species with lower HOMO–LUMO gap are predicted to have higher carrier mobility and lower kinetic stability.