The photocatalytic yield of the g-C3N4 for CO2 reduction was modified by phosphorus doping. The possible reaction pathways for CO2 reduction on the P-doped g-C3N4 (PCN) surface were investigated by DFT calculations for the first time. The experimental results showed that P doping improves the production of CH4 through the increase in the driving force of the electrons. The partial density of states of the PCN showed that the VBM and CBM are composed of px, py and s orbitals of the N atoms and pz states of carbon, nitrogen, and phosphorus, respectively and therefore, the P-doping increase carriers lifetime. Mechanism studies confirm that formic acid, formaldehyde, methanol and methane are the most probable products. The methane having positive adsorption energy can be easily desorbed from the PCN surface and the Gibbs activation energy of the final step is 1.98 eV. The formation of H2COOH is the rate-determining step.

Here, photovoltaic behaviors of the human-shaped molecules named Nanokid and Nanoathlete (monomeric forms) and Nanoputain dimer1 and Nanoputain dimer2 (hetero-dimers) based on the quantum chemistry were investigated. For all studied anthropomorphic molecules, tuning the electrophilicity decreases the energy barrier of the electron injection. Nanokid and Nanoathlete have greater activity against solar light, which shows more favorable photovoltaic parameters. Although Nanoputain dimers represent better charge transfer indices and intramolecular charge transfer, they have low oscillating strength. The maximum peaks of the current and efficiency in different absorption wavelengths are originated from the increase in the light-harvesting efficiency and decrease in the energy barrier of the electron injection. Finally, Nanokid and Nanoathlete are proposed as better candidates to be used in the photovoltaic cells.

In this research, dynamics, and kinetics of some metal-free organic dyes based on triphenylamine having a D-π-A type structure were investigated in the gas phase and solvent (ethanol, dichloromethane, toluene, tetrahydrofuran, chloroform, and dimethylformamide) using the quantum chemistry calculations. These structures consist of triphenylamine as the donor linked to the acceptor units of cyanoacrylic acid and benzoic acid via different π-conjugated systems. The obtained results show that TC601 dye having the ethynyl anthracene phenyl -conjugated system has the preferred charge/hole transfer properties (Ginj/Greg), which in ethanol as the solvent, the lowest values of Ginj and Greg were evaluated. Molecular spectroscopic properties of the studied dyes reveal that H-P and F-P dyes have favorable molar absorption coefficients in all media. Also, the behaviors of the light-harvesting efficiency (LHE) and incident photon to current efficiency (IPCE) as the functions of the wavelength were analyzed, which show that the presence of solvent increases the values of IPCE and LHE for most studied dyes in comparison with the gas phase. Finally, based on different analyses, TC601 as the dye and ethanol as the solvent are proposed as the preferred candidates to be applied in the DSSCs.

In this paper, Tetraphenyldipyranylidene (DPPh), a large quinoidal planar π-conjugated heterocyclic, was considered as primary organic molecule in organic field effect transistors (OFETs). Electron-withdrawing atoms such as F, Cl, and Br were attached to the H-atoms of four peripheral phenyl groups of para-positions relative to the O-atoms of DPPh. Density functional theory (DFT) calculations at the M06-2X/6-311G++ (d,p) level were performed. The influences of the different electron-withdrawing atoms such as F, Cl, and Br on the electronic and optical properties, charge transport parameters, and charge carrier mobility were investigated. The absorption and emission spectra of the DPPh and its derivatives were theoretically simulated in OFETs. The simulated spectra show an intense peak in the visible region (400-650 nm), in which the highest adsorption/emission intensity is related to DPPh-Br. Moreover, the charge injection energy barrier of DPPh and its derivatives were calculated by considering Pt as the source electrode. Based on the results, a greater hole transport is predicted than the electron transport. Moreover, the obtained ratio of the hole/electron mobility and the theoretical correlations between the charge transport parameters of monomers and dimers show that the insertion of the electron-withdrawing atoms in the DPPh structure is a promising strategy to have an ambipolar or n-type semiconductor, too. The obtained results show that introducing electron-withdrawing atoms at the para-position of the DPPh improves the hole/electron injection and transport process in the OFET devices. Finally, DPPh-Br shows a great performance in comparison with the substituted F and Cl atoms in the OFETs devices.

In this study, the photovoltaic properties of the organic dyes based on triphenylamine having a D--A structure including TC201, TC202, TC203, TC601, H-P, F-P, FF-P, T-F, and P1B were investigated theoretically. In this model, triphenylamine was used as an electron donor, cyanoacrylic acid, and benzoic acid as the electron acceptors, and anthracene phenyl, anthracene vinyl phenyl, anthracene ethynyl phenyl, ethynyl anthracene phenyl, styryl phenyl, styryl-2-fluorophenyl, styryl-2,6-difluorophenyl, styryl furan, and styryl as the π-conjugated systems. The results show that a change in the -conjugated system and electron acceptor affect the properties of the dye-sensitized solar cell (DSSC). Also, TC601 dye having the ethynyl anthracene phenyl -conjugated system shows the highest charge transfer distance (DCT) and the least overlap of the electron-hole distribution (S) in comparison with other dyes. Moreover, the presence of a triple bond in the vicinity of triphenylamine increases the resonance effect of the -electrons that facilitates the process of charge transfer in this dye. Spectroscopic analysis shows that H-P and F-P dyes have the higher molecular absorption coefficients and TC202, TC203, F-P, and T-F dyes show a red shift in comparison with other dyes. Moreover, the voltage-current curve of the studied dyes shows that the highest values of the open circuit voltage and short circuit current density are related to P1B and TC601 dyes, respectively. Finally, TC601 and P1B are proposed as the best candidates to be used in the DSSCs due to their maximum incident photon to current conversion efficiency.

Biosensors are the analytical tools with great application in healthcare, food quality control, and environmental monitoring. They are of considerable interest to be designed by using cost-effective and high efficient approaches. Designing biosensors with improved functionality or application in new target detection has been converted to a fast-growing field of biomedicine and biotechnology branches. Experimental efforts have led to valuable successes in biosensor designing; however, some deficiencies limit their utilization for this purpose. Computational design of biosensors has been introduced as a promising key to eliminate the gap. A set of reliable structure prediction of the biosensor segments, their stability, and accurate descriptors of molecular interactions are required to computationally design of biosensors. In this review, we provide a comprehensive insight into the progress of computational methods to guide the biosensor design, including molecular dynamics (MD) simulation, quantum mechanics (QM) calculations, molecular docking, virtual screening, and a combination of them as the hybrid methodologies. With relying on the recent advances in computational methods, an opportunity has been emerged for them to be complementary or alternative to the experimental methods in the field of biosensor design.

Photovoltaic properties of the natural dyes of chlorophylls consist of Chl a, Chl b, Chl c2, Chl d, Phe a, Phe y and Mg-Phe a, were studied in the gas phases and water. The extension of the π-conjugated system, the substitution of the central Mg2+ and proper functional groups in the chlorophyll structures can amplify the charge transfer and photovoltaic performance. Chl a shows more favorable dynamics of charge transfer than other studied chlorophylls. Chl d, Phe a, Phe y and Mg-Phe a, have a greater rate of the exciton dissociation in comparison with Chl a, Chl b, and Chl c2 originated from a lower electronic chemical hardness, a lower exciton binding energy, and a bigger electron-hole radius. As a result, better efficiencies of the light-harvesting and energy conversion of the chlorophylls mainly appear in the Soret band. The LHE values of the chlorophylls in water show that solvent favorably affects the ability of light-harvesting of the photosensitizers. Finally, based on the energy conversion efficiency, Chl a, Phe a, and Mg-Phe a, are proposed as the best candidates for using in the dye-sensitized solar cells.

Photovoltaic properties of the natural dyes of chlorophylls consist of Chl a, Chl b, Chl c2, Chl d, Phe a, Phe y and Mg-Phe a, were studied in the gas phases. The extension of the π-conjugated system, the substitution of the central Mg2+ and proper functional groups in the chlorophyll structures can amplify the charge transfer and photovoltaic performance. Chl a shows more favorable dynamics of charge transfer than other studied chlorophylls. Chl d, Phe a, Phe y and Mg-Phe a, have a greater rate of the exciton dissociation in comparison with Chl a, Chl b, and Chl c2 originated from a lower electronic chemical hardness, a lower exciton binding energy, and a bigger electron-hole radius. As a result, better efficiencies of the light-harvesting and energy conversion of the chlorophylls mainly appear in the Soret band. Finally, based on the energy conversion efficiency, Chl a, Phe a, and Mg-Phe a, are proposed as the best candidates for using in the dye-sensitized solar cells.