Charge transport rate is one of the key parameters determining the performance of organic electronic devices. In this paper, we used density functional theory (DFT) at the M06-2X/6−31+G(d) level to compute the charge transport rates of nine coronene topological structures. The results show that the energy gap of these nine coronene derivatives is in the range 2.90-3.30 eV, falling into the organic semiconductor category. The size of the conjugate ring has a large influence on the charge transport properties. Incorporation of methyl groups on the rigid core of tetrabenzocoronene and hexabenzocoronene is more conducive to the hole transport of the molecule than incorporating methoxyl groups. The derivatisation of a 'long plate-like' coronene with methoxyl groups facilitates both hole and electron transport. This class of molecules can thus be used in the design of ambipolar transport semiconductor materials.

Charge transport rate is one of the key parameters determining the performance of organic electronic devices. Based on density functional theory, exchange-correlation functionals which adequately account for non-covalent interactions, such as M06-2X and wB97XD, should significantly improve the accuracy of charge transport rate calculations for large systems with non-covalent interactions. In this work, the B3LYP hybrid functional, the variant hybrid functional M06-2X, and the long-range-corrected wB97XD functional were used to perform geometry optimizations and charge transport rate calculations on 11 variants of tetrabenzo[ a,d,j,m]coronene, including tetrabenzo[ a,d,j,m]coronene itself and its tetra-substituted and octa-substituted derivatives. Our results indicate that the molecular geometries of these benzocoronene semiconductors are large quasi-planar conjugated π systems, and the incorporation of different substituents significantly affects their frontier molecular orbitals. The hole carrier mobility ( µ+) and electron carrier mobility ( µ−) of the methoxy-substituted derivatives (TBC(OCH3)4 and TBC(OCH3)8) were relatively low. The results of the tetrabenzo[ a,d,j,m]coronene molecules studied were consistent with using the aforementioned M06-2X, wB97XD, and B3LYP methods. We found that the octa-substituted derivatives (TBCF8, TBCCl8, TBC(CH3)8, and TBC(CN)8) could be used as p-type organic semiconductor materials.

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Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2',3'-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 10 7 atomic units (10 −33 esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g.-N(CH 3) 2 or-NHCH 3) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.

Based on density functional theory, quantum chemical calculations of the charge-transport rates were performed for five disc-shaped coronene derivatives with varying numbers of fused thiophene rings, using different basis sets 6-31+G(d) and 6-311++G(d,p), hybrid functionals (B3LYP, M06-2X, CAM-B3LYP, WB97XD, M08-HX), and a dispersion-corrected hybrid functional (M06-2X+D3). Our results indicate that increasing the basis set and adding diffusion and polarisation functions had little effect on the molecular reorganisation energy, charge-transport matrix element t, and charge carrier mobility μ. The charge carrier mobility calculated using B3LYP were relatively large, whereas the results calculated using CAM-B3LYP and WB97XD were similar. Among the five coronene derivatives, molecule b with one thiophene ring could be candidates for a n-type organic semiconductor, and molecule c with two thiophene rings can be designed as a p-type semiconductor.