Application of double-hybrid density functionals to charge transfer in N-substituted pentacenequinones

Abstract

A set of N-heteroquinones, deriving from oligoacenes, have been recently proposed as n-type organic semiconductors with high electron mobilities in thin-film transistors. Generally speaking, this class of compounds self-assembles in neighboring π -stacks linked by weak hydrogen bonds. We aim at theoretically characterizing here the sequential charge transport (hopping) process expected to take place across these arrays of molecules. To do so, we need to accurately address the preferred packing of these materials simultaneously to single-molecule properties related to charge-transfer events, carefully employing dispersion-corrected density functional theory methods to accurately extract the key molecular parameters governing this phenomenon at the nanoscale. This study confirms the great deal of interest around these compounds, since controlled functionalization of model molecules (i.e., pentacene) allows to efficiently tune the corresponding charge mobilities, and the capacity of modern quantum-chemical methods to predict it after rationalizing the underlying structure-property relationships.

Double-hybrid density functionals: merging wavefunction and density approaches to get the best of both worlds

“…This is not a trivial conclusion, which have contributed lately to the vivid debate in literature about half-metallicity of graphene, since a non-vanishing singlet-triplet energy gap is predicted at all other DFT levels, after the corresponding initial polarisation of spin-densities yielding antiferromagnetic systems, and only high-level CCSD(T) calculations reverse the situation indicating a vanishing singlet-triplet energy gap [172]. Another recent application for the field of materials science is the study of n-channel organic semiconductors based on N-heteroquinones [173], see Figure 7. The link to charge mobility values in the diffusive regime, where the charge carriers migrate across the molecular crystal through sequential (hopping) chargetransfer events involving a pair of neighbouring molecules, needs to access to the (sometimes unknown) dimer geometry.…”

Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

“…109 When looking at corresponding rates for electron transport, we obtain a value of 3.5 × 10 13 s −1 , which also compares favourably with halogenated oligoacenes 74 although it is still an order of magnitude lower than for other materials such as some state-ofthe-art pentacenequinones. 110 Most importantly, these rates might anticipate a great behavior, because for purely diffusive quasi-1D motion, the Einstein-Smoluchowski equation reads as 30,111 …”

DFT Study of the Ambipolar Character of Polymers on the Basis of s-Tetrazine and Aryl Rings

“…IP and EA are also key parameters that determine the efficiency of the injection of charges from electrodes as well as the ease to be reduced or oxidized upon air exposure. 26 Thus, the EA of a semiconductor should amount to no less than 3.0 eV for an easy electron injection, but not much greater than 4.0 eV to avoid its stability in ambient conditions was compromised. 6 Low IPs facilitate hole injection but too low values can produce unintentional doping.…”