DFT Based Modeling of Asymmetric Non-Fullerene Acceptors for High-Performance Organic Solar Cell

AbstractFive new asymmetric NFA-based polymer solar cells i.e., N1-N5 are designed by doing modification in terminal groups of the acceptor part of experimentally synthesized reference molecule with (4,4,9,9-tetramethyl-4,9 dihydroselenopheno [2’,3’:5,6]-s-indaceno [1,2-b] thiophene) core. Frontier molecular orbital analysis is used to study their photovoltaic and optoelectronic properties. It confirmed the electrons' transportation from the donor to the acceptor part. It stated that all molecules have a lower bandgap than R and N2 has the lowest bandgap of 2.01 eV. The molecular orbital potential analysis confirmed the electron-withdrawing properties of the terminal groups. Optical properties studies evaluated maximum absorption with transition energies. All newly designed molecules N1-N5 show higher λmax values than R i.e., in the range of 680-740 nm with N2 having the highest λmax of 735 nm and lowest transition energy of 1.69 eV. Dipole moment studies showed that N3 has a maximum dipole moment of 7-40 D with all others having comparable values. TDM plots confirmed the electron shifting from donor to acceptor region. Reorganization energy analysis showed that N1 and N3 have the lowest reorganization energy values thus giving the highest electron mobilities. Voc calculated results of all molecules N1-N5 have lower values than R when coupled with PTB7-Th donor polymer. Charge transport analysis of N2 and PTB7-Th coupled molecule confirmed the acceptor type nature of our designed molecules.

Frontier molecular orbital engineering in spiro-based molecules: achieving aggregation induced delayed fluorescence for non-doped OLEDs

Frontier molecular orbital engineering has been demonstrated to achieve aggregation induced delayed fluorescence (AIDF) for non-doped OLEDs. As a proof of concept, a new model compound AT-spiro-DMACF is reported on...

Engineering of flat bands and Dirac bands in two-dimensional covalent organic frameworks (COFs): Relationships among molecular orbital symmetry, lattice symmetry, and electronic-structure characteristics

Two-dimensional covalent organic frameworks (2D-COFs), also referred to as 2D polymer networks, display unusual electronic-structure characteristics, which can significantly enrich and broaden the fields of electronics and spintronics. In this...

Theoretical study of gallium nitride nanocage as a carrier for Cisplatin anticancer drug

In this paper, the possible interactions between cisplatin Cl2H6N2Pt as an anticancer drug and gallium nitride (Ga12N12) nanocage have been investigated using the DFT/b3lyp/lanl2dz(d,p) level of theory. Three different orientations were used to mimic the cisplatin adsorbed on Ga12N12. To investigate the interaction mechanism between the two components, the adsorption energies and thermodynamic parameters, the electronic properties such as the energies and orbitals distribution of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), the HOMO-LUMO energy gaps (Eg), thermodynamic properties were also investigated. Additionally, some quantum molecular descriptors were calculated to understand molecular reactivity. The main results revealed that the adsorption process of the drug compound on the surface of the nanocage varies with the adsorption site. The process showed that different energies could be obtained, where the highest energy value was when the drug compound was adsorbed with the nanocage at the chlorine atom, with a value of (41.85) kcal/mol. On the other hand, the distance between the drug compound atoms was affected before and after adsorption, which proves the existence of an interaction between the drug compound and the nanocage and considers it as a drug delivery vehicle.

EFFECT OF ASYMMETRIC LATERAL LINKING GROUPS ON THE ELECTRONIC TRANSPORT IN MOLECULAR DEVICE

The effect of asymmetric lateral linking groups on the electronic transport is investigated in the biphenyl molecule-based device with gold electrodes with the framework of density functional theory and nonequilibrium Green’s function. The asymmetric lateral linking groups reduce the currents of molecular junctions, and result in the reverse rectifying behavior. The devices with asymmetric lateral linking groups –SH and –SCH3 have maximum rectifying ratios, while the asymmetric lateral linking group –SH and –NH2 cause minimum rectifying ratios. The calculated results suggest that the asymmetric lateral linking group induces the reduced coupling between molecule and right electrode, asymmetric distribution of frontier molecular orbital and asymmetric evolution of the molecular orbital eigenenergies, accounting for the rectifying behavior.

Structure-antioxidant Activity Relationships of Dendrocandin Analogues Determined Using Density Functional Theory

Quantum-chemical calculations based on the density functional theory (DFT) at the B3LYP/6–311++G(2d,2p)//B3LYP/6–31G(d,p) level were employed to study the relationship between the antioxidant properties and chemical structures of six dendrocandin (DDCD) analogues in the gas phase and two solvents (methanol and water). The hydrogen atom transfer (HAT), electron-transfer-proton-transfer (ET-PT), and sequential proton-loss-electron-transfer (SPLET) mechanisms are explored. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), reactivity indices (η, μ, ω, ω+, and ω–), and molecular electrostatic potentials (MEPs) were also evaluated. The results suggest that the D ring plays an important role in mediating the antioxidant activity of DDCDs. For all the studied compounds, indicating that HAT was identified as the most favorable mechanism, whereas the SPLET mechanism was the most thermodynamically favorable pathway in polar solvents. The results of our study should aid in the development of new or modified antioxidant compounds.

Investigating fullerene-oxide nanostructure as an adsorbent of ammonia: Complexation efficiency by density functional theory

A model of OC20 fullerene-oxide (FO) was investigated in this work for adsorbing the ammonia (NH3) substance by the hypothesis of formations of bimolecular complexes of the two substances. To affirm such hypothesis, the models of singular NH3 and FO were optimized to reach the minimized energy structures and all possibilities of their interactions configurations were examined. As a consequence, three NH3@FO bimolecular complex models were obtained for reaching the point of complex formations. Details of interactions indicated both direct and indirect contributions of the oxidized region of FO to interactions with both H and N atomic sites of NH3. In this regard, CPLX3 with two types of H. . . O and N. . . C interactions was seen to be at the highest strength of adsorption and complex formation in comparison with CPLX1 and CPLX2 models including only one interaction of each of H. . . O and N. . . C type, respectively. Moreover, the obtained electronic molecular orbital features revealed the sensor function of FO material versus the NH3 substance. As a consequence, the hypothesis of NH3@FO complexes formation was affirmed with two proposed functions of removal and detection for the investigated FO material. All results of this work were obtained by details through performing density functional theory (DFT) calculations.

Collective residue interactions in trimer complexes of SARS-CoV-2 spike proteins analyzed by fragment molecular orbital method

In large biomolecular systems such as protein complexes, there are huge numbers of combinations of inter-residue interactions whose comprehensive analyses are often beyond the intuitive processing by researchers. Here we propose a computational method to allow for a systematic analysis of these interactions based on the fragment molecular orbital calculations, in which the inter-fragment interaction energies are comprehensively processed by the singular value decomposition. For a trimer complex of SARS-CoV-2 spike protein, three-body interactions among residues belonging to three chains are analyzed to elicit a small number of essential interaction modes or networks crucial for the structural stability of complex.