Quantum chemical calculations on molecules with donor-π-acceptor structures for efficient organic field effect transistor

Abstract

Novel organic compounds for possible use in organic field effect transistors (OFETs) have been widely researched in recent times. Polythiophene [1] was the first organic compound to be used for development of OFET in 1986. OFETs with p-type semiconductor properties have been found to be most suitable for designing of devices, since stability of such compounds is higher as compared to n-type semiconducting compounds. In this paper, two molecular structures (naphthalene-pyrrole-propanoic acid and naphthalene-pyrrole-pyridine) have been designed based on the donor-π-acceptor architecture. Both structures were optimized using density functional theory (DFT) at B3LYP/6–31 + G(d,p) theory level. These structures were also checked to confirm whether they correspond to global minima on potential energy surface (PES) through frequency calculation in the Gaussian 16 W software package. Thorough analysis of calculated parameters such as hole reorganization energy (λh), electron reorganization energy (λe), ionization potential (vertical and adiabatic) and electron affinity (vertical and adiabatic), has been done to investigate charge transport properties. In both the designed systems, λh values were found to be smaller as compared to λe values. Hence, it may be inferred that our designed molecules have holes as majority charge carriers and can be utilized as p-type semiconductors. Behavior of both designed molecules under electric field was also checked to determine their feasibility for use as conducting channel in OFET.