Modeling Electron and Hole Transport in Fluoroarene‐Oligothiopene Semiconductors: Investigation of Geometric and Electronic Structure Properties

Abstract

A theoretical study using density functional theory is undertaken to gain insight into how the structural, electronic, and electron‐transfer characteristics of three Fluoroarene‐oligothiophene semiconductors influence the preferred transport of electrons versus holes in field‐effect transistor applications. The intermolecular electronic coupling interactions are analyzed through both a simplified energy‐splitting in dimer (ESID) model and as a function of the entire dimer Hamiltonian in order to understand the impact of site energy differences; our results indicate that these differences are generally negligible for the series and, hence, use of the ESID model is valid. In addition, we also investigate the reduction and oxidation processes to understand the magnitudes of the intramolecular reorganization energy for the charge‐hopping process and expected barrier heights for electron and hole injection into these materials. From the electronic coupling and intramolecular reorganization energies, estimates of the nearest‐neighbor electron‐transfer hopping rate constant for electrons are obtained. The ionization energetics suggest favored electron injection for the system with perfluoroarene groups at the end of the thiophene core, in agreement with experiments. The combined analyses of the electron‐transfer properties and ionization processes suggest possible ambipolar behavior for these materials under favorable device conditions.

Bis(arylene-ethynylene)-s-tetrazines: A Promising Family of n-Type Organic Semiconductors?

“…The internal reorganization energies (λ i ) previously reported for a set of Ar 67 and core-twisted chlorinated perylene bisimide (0.30 -0.34). 68 However, the presence of the ethynylene bridges in (ArCC) 2 Ph derivatives substantially lowers λ i to values comparable to those reported for the above mentioned reference compounds (see Table 1).…”

Theoretical estimation of the rate of photoinduced charge transfer reactions in triphenylamine C60 donor–acceptor conjugate

“…As mentioned before, the reliable evaluation of this parameter is difficult to achieve. Some authors set the value of λext as an adjustable parameter; [80,81] on the other hand, the direct evaluation of λext can be consistently performed via QM/MM [82] or a polarizable force field. [83] It is expected that QM/MM would provide a more accurate value for λext, yet it is required that the polarizability of the molecular fragments can be validated through experiments; a condition that is not fulfilled for the system under study.…”

Optoelectronic and Semiconducting Properties of Conjugated Polymers Composed of Thiazolo[5,4-d]thiazole and Arene Imides Linked by Ethynylene Bridges

“…In general, t 12 -values calculated for polymers I, II and particularly IV lie in the range of those reported for the different pathways within the pentacene crystal (0.043 − 0.084 eV, calculated at B3LYP/6-31G** level from a crystal structure) 97 and for analogous systems, such as oligothiophenes made up of 6 repeat units (0.132 eV, calculated at the B3LYP/6-31G** level) and short oligomers formed by thiophene rings and perfluoro-phenyl units (0.01 -0.07 eV, calculated at the B3LYP/6-31G** level). 98 In the case of hole transport, t 12 + values calculated for polymers I -V, especially for II and IV, are comparable to the values reported for oligomers such as oligothiophene with n = 6 (0.135 eV, calculated at the B3LYP/6-31G** level), short oligomers formed by thiophene rings and fluoroarenes-thiophenes (0.031 − 0.057 eV, calculated at the B3LYP/6-31G** level), 98 and compounds such as thiophene-pyrrole based oligoazomethines. 99 It is worth mentioning the strong differences calculated for the electron couplings of the polymers III and IV which present related structures.…”