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The charge transport properties of a series of rubrene derivatives were systematically investigated by density functional theory and molecular dynamics (MD) simulations. It was found that functionalizing electron-withdrawing groups (−CN, −CF3, or fluorination) on the peripheral phenyls not only enhance the chemical stability of materials but also favor electron injection by lowering the energy levels of frontier molecular orbitals and increasing the electron affinities. Derivatives 2–5 and 9, exhibiting packing motifs similar to rubrene but closer π-stacking distances, possess large hole and electron-transfer integrals, significant bandwidths, and small effective masses, suggesting excellent ambipolar semiconductor behavior. The maximum hole­(electron) mobilities in the Marcus hopping mechanism based on kinetic Monte Carlo simulation can reach 14.0–16.5(1.6–3.5) cm2 V–1 s–1. Interestingly, the antiparallel 2-D brick stacking and twisted backbones of fluorinated derivatives 11 and 12 result in nearly 1-D percolation network but balanced hole and electron transport property. In contrast, the parallel 2-D brick stacking of 14 leads to 2-D percolation network. Their maximum hole and electron mobilities fall in the range of 0.5–3.6 and 2.0–4.8 cm2 V–1 s–1. Furthermore, MD simulations show that dynamic disorder is strongly detrimental to the hole transfer but has a little influence on the electron transfer for 1–5. Moreover, severe twist of backbones of 9 leads to almost 1 order of magnitude lowered mobility. In addition, the influences of different substituents on the molecular structure, packing motif, and intermolecular reorganization energy are discussed.

Two-photon photodynamic therapy (TP-PDT), as a new method for cancer, has shown unique advantages in tumors. A low two-photon absorption cross-section (δ) in the biologic spectral window and a short triplet state lifetime are the important issues faced by the current photosensitizers (PSs) in TP-PDT. In this paper, the photophysical properties of a series of Ru(II) complexes were studied by density functional theory and time-dependent density functional theory methods. The electronic structure, one- and two-photon absorption properties, type I/II mechanisms, triplet state lifetime, and solvation free energy were calculated. The results showed that the substitution of methoxyls by pyrene groups greatly improved the lifetime of the complex. Furthermore, the addition of acetylenyl groups subtly enhanced δ. Overall, complex 3b possess a large δ(1376 GM), a long lifetime (136 μs), and better solvation free energy. It is hoped that it can provide valuable theoretical guidance for the design and synthesis of efficient two-photon PSs in the experiment.

To obtain anthracene-based derivatives with electron transport behavior, two series of anthracene-based derivatives modified by trifluoromethyl groups (−CF3) and cyano groups (−CN) at the 9,10-positions of the anthracene core were studied. Their electronic structures and crystal packings were also analyzed and compared. The charge-carrier mobilities were evaluated by quantum nuclear tunneling theory based on the incoherent charge-hopping model. Our results suggest that introducing −CN groups at 9,10-positions of the anthracene core is more favorable than introducing −CF3 to maintain great planar rigidity of the anthracene skeleton, decreasing more lowest unoccupied molecular orbital energy levels (0.45–0.55 eV), reducing reorganization energies, and especially forming a tight packing motif. Eventually, the excellent electron transport materials could be obtained. The molecule 1-B in Series 1 containing −CF3 groups is an ambipolar organic semiconductor (OSC) material with a 2D transport network, and its value of μh‑max/μe‑max is 1.75/0.47 cm2 V–1 s–1 along different directions; 2-A and 2-C in Series 2 with −CN groups are excellent n-type OSC candidates with the maximum intrinsic mobilities of 3.74 and 2.69 cm2 V–1 s–1 along the π–π stacking direction, respectively. Besides, the Hirshfeld surface and quantum theory of atoms in molecules analyses were applied to reveal the relationship between noncovalent interactions and crystal stacking.

At present, the high-performance organic semiconductor materials based on the small aromatic anthracene-core and its derivatives develop comparatively slow, which largely due to the lack of a profound understanding with...