Influence of the substitution on the electronic properties of perylene-3,4:9,10- bis(dicarboximides): density functional theory study

A Irfan

doi:10.4314/bcse.v28i1.12

Abstract

Geometries of the substituted perylene-3,4:9,10-bis(dicarboximides) (PDI) and their radical anions have been optimized at the B3LYP/6-31G** level of theory. The adiabatic and vertical electron affinities have been computed at the B3LYP/6-31+G*//B3LYP/6-31G** level. Substitution of the PDI with COOCF 3 reduces the energies of both the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) with the only exception of PDI4 derivative. Calculations predict a decrease in the electron injection barrier in the materials based on the proposed compounds comparing to the parent PDI. Taking into account the calculated electron affinities (EA), the air stability and ambipolar behavior of the materials under study can be expected. KEY WORDS : Organic field effect transistors, Highest occupied molecular orbitals, Lowest unoccupied molecular orbitals, Electron affinity, Air stability Bull. Chem. Soc. Ethiop. 2014 , 28(1), 101-110. DOI: http://dx.doi.org/10.4314/bcse.v28i1.12

Highlights

In recent years, organic semiconductors have attracted considerable attention because of their potential for creating low-cost, portable electronic and optoelectronic devices such as organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), flexible displays, and sensors [1,2,3]
N-type semiconductors should possess low lowest unoccupied molecular orbital (LUMO) energy which in turn results in large electron affinity which should be close to the work function of the source-drain electrodes, yielding smaller charge injection barrier for electron to ensure the effective charge injection from the source electrode
Remarkable progress has recently been made in developing new n-channel organic semiconductors, only a few n-channel OFETs can operate under ambient conditions because of unstable radical anions [12]

Summary

Introduction

Organic semiconductors have attracted considerable attention because of their potential for creating low-cost, portable electronic and optoelectronic devices such as organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), flexible displays, and sensors [1,2,3]. The oligothiophenes bearing carbonyl groups have been exploited as n-type OFET materials [29,30,31,32,33,34,35], where it was explained that trifluoroacetyl groups at the terminal positions of the π-conjugated backbone is effective in lowering the LUMO energy level and arranging the molecules in crystals [36].

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