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Four new Donor-Acceptor (D-A) type oligothiophenes based structures (C1–C4) were designed by substituting different acceptors moieties around tetrahedral silicon core to simulate their photovoltaic properties. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) quantum analysis were carried out to reconnoiter various parameters of solar cells. A comparative analysis has conducted between designed structures and reference molecule R to conclude our simulated results. Among all the structures, C2 has displayed highest absorption values (380 nm) with red shift and minimum band gap (ΔH-L) of 4.11 eV in dichloromethane at DFT-CAM-B3LYP/6-31G (d,p) using IEFPCM model. The C2 has also shown the lowest values of electron reorganization energy (λe = 0.018eV) and hole reorganization energy (λh = 0.015eV) therefore, could be suggested for use in organic solar cells because of its most noteworthy charge carrier mobilities. Again, C2 has the different trend in TDM graph because the electron density is present in the lower right part of core unit and in the acceptor moiety due to high electron affinities of end capped acceptor having cyanide groups.

For the maximum photovoltaic outputs, molecular modelling was incurred in reported molecules BDCl2F and TClC2F - having PCE value up to 12.4% - to make six novel unfused non-fullerene acceptors. A deep theoretical consideration under the umbrella of TD-DFT and DFT - using method MPW1PW91 with basis set 6-31G (d,p) - was used to look into molecular geometries and molecular electrostatic potential (MEP), optical (the excitation energy and molar absorption coefficient) and photovoltaic parameters [frontier molecular orbitals (FMOs), the density of states (DOS), light-harvesting efficiency (LHE), transition density matrix (TDM), binding energy, reorganization energy, charge transfer properties (open circuit voltage) and fill factor (FF)]. In this work, the modelled molecules have depicted extraordinary structural, optical and photovoltaic characteristics which validate the successful modelling to advance the polymer solar cell (PSC) technology. Out of all explored entities, BDCl2F-AS and TClC2F-AS embarked excellent results (λ max = 859.2 nm and 879.2 nm, µe = 13.48 and 11.79, LHE = 0.9994 and 0.9993, respectively). Similarly, BDCl2F/ PTB7-Th and TClC2F PTB7-Th donor/acceptor interfaces have excellent output values (Voc = 1.21 eV and 1.16 eV, normalized Voc = 46.7633 eV and 44.8309 eV with fill factor (FF) = 0.8982 and 0.8949, respectively). The increase in all analysed parameters comparative to experimentally reported molecules BDCl2F and TClC2F have urged to predict PCE of modelled molecules to be greater than 12.4% which is the PCE values of reported ones. By keeping in mind the entire results, modelled molecules and their interfaces are recommended for PSCs manufacturing usage.

In this research, for the first time; graphyne is investigated as a carrier for delivery of anticancer drug, daunorubicin. The effectiveness of graphyne as a carrier, is explored with the help of calculations of some physiochemical properties such as band-gap, dipole-moment, and chemical-reactivity-descriptors for daunorubicin drug, graphyne carrier and daunorubicin-graphyne complex by using Density Functional Theory (DFT) method. Daunorubicin has significant antimitotic and cytotoxic activity as it can form complex with DNA by intercalation. The nature of interactions between graphyne and daunorubicin complex are clarified through noncovalent-interaction (NCI) analysis, which demonstrated that Vander-Waals force of interactions are present between the graphyne carrier molecule and daunorubicin drug. Daunorubicin drug will easily off-load at the target point as weak forces are present between drug and graphyne carrier. Frontier-molecular-orbital-analysis explained that how charge-transferred from daunorubicin to graphyne in complex formation process. The charge-transfer process is further studied by charge-decomposition-analysis (CDA). The calculations at excited-state indicated that the λmax of daunorubicin-graphyne complex show red-shift of 91 nm. PET process is also studied for excited-states of daunorubicin-graphyne complex with the help of electron-hole theory and it revealed that fluorescence-quenching process will occur in complex molecule. The process of fluorescence-detection is very useful for systematic delivery of daunorubicin drug at target site for the perfect treatment. Moreover, the effect of + 1 and −1 charge-state on graphyne molecule and its complex with daunorubicin is also investigated. Overall, the calculations suggested that graphyne could be utilized as an efficient carrier for targeted-delivery of daunorubicin.