3d-transition metals (Cu, Fe, Mn, Ni, V and Zn)-doped pentacene π-conjugated organic molecule for photovoltaic applications: DFT and TD-DFT calculations

Tuning the Electronic and Optical Properties of Crystalline Anthracene by Doping and Pressure for Photovoltaic Applications

Despite their numerous advantages, organic molecular crystals are often unsuitable for photovoltaic applications due to their poor optoelectronic properties. Here we employ density functional theory to show that the combination of substitutional doping and hydrostatic pressure can effectively tune the structural, electronic, and optical properties of crystalline anthracene. Specifically, we aim to reduce the electronic band gap of crystalline anthracene in order to improve its optical absorption, so that the modified materials become suitable for use in solar cells. Our results reveal that lattice parameters and bond lengths decrease with pressure, hence strengthening interactions between atoms and narrowing the band gap. Doping also reduces the band gap significantly. In the end, three materials studied in the current research display close-to-ideal band gaps: O-doped anthracene under 8.75 GPa of pressure (1.353 eV), P-doped anthracene under 10 GPa (1.073 eV), and S-doped anthracene under 2.5 GPa (1.341 eV). Furthermore, they exhibit high absorption coefficient values on the order of 105 cm-1 within the visible light range, a noteworthy improvement over pure anthracene. Therefore, we have successfully tuned the optoelectronic properties of crystalline anthracene and identified three ideal candidates for solar cell materials.

Synthesize of an Azo Compound: Investigation its Optical Nonlinear Properties and DFT Study

In the present work, a diazonium salt is prepared by a diazonium reaction of sulfamerazine in the presence of aqueous hydrochloric acid and sodium nitrate. Structural confirmation of azo compounds synthesize is achieved by mass spectrometry, infrared spectroscopy, and 1H, 13C nuclear magnetic resonance. The sample geometry is derived using Density Functional Theory (DFT) and DT-DFT applied to the basis set B3LYPL6-311 + G(d,p). An investigation is conducted on the optical nonlinear (ONL) properties of the azo compounds formed under the excitation with a low power 532 nm laser beam using diffraction patterns (DPs) and a typical Z-scan combined with optical limiting. The Fresnel-Kirchhoff integral provides numerically obtained boundary conditions in the sense of experimentally obtained values. As high as 2 × 10-7 cm2/W of nonlinear refractive index (NLRI), n2, 1.24 × 10-3 cm/W of the nonlinear absorption coefficient (NLAC), β, and 15.5 mW of the optical limiting (OL) threshold, TH, are obtained.

Theoretical design of phosphorus-doped perylene derivatives as efficient singlet fission chromophores

Singlet fission (SF) is considered as a promising strategy to overcome the Shockley-Queisser limit of single-junction solar cells. However, only a handful of chromophores were observed to undergo SF to date. To broaden the number of SF chromophores, we designed a series of phosphorus-doped perylenes based on the diradical character strategy and examined their SF feasibility using theoretical calculations. By analysis of frontier orbitals, diradical character and aromaticity, SF-capable candidates were prescreened. These analyses reveal that the diradical character of perylene is effectively enhanced by P-doping at bay- and peri-positions of perylene, making SF more thermodynamically feasible. However, the diradical character remains nearly unchanged when P atoms are doped at ortho-positions because the spin center cannot be stabilized, leading to a more endothermic SF. This study shows how SF-related energies and diradical character of SF chromophores are altered by P doping, and extends the SF-capable molecular library.

Exploring the structural, electronic, and hydrogen storage properties of hexagonal boron nitride and carbon nanotubes: insights from single-walled to doped double-walled configurations

This study investigates the structural intricacies and properties of single-walled nanotubes (SWNT) and double-walled nanotubes (DWNT) composed of hexagonal boron nitride (BN) and carbon (C). Doping with various atoms including light elements (B, N, O) and heavy metals (Fe, Co, Cu) is taken into account. The optimized configurations of SWNT and DWNT, along with dopant positions, are explored, with a focus on DWNT-BN-C. The stability analysis, employing binding energies, affirms the favorable formation of nanotube structures, with DWNT-C emerging as the most stable compound. Quantum stability assessments reveal significant intramolecular charge transfer in specific configurations. Electronic properties, including charge distribution, electronegativity, and electrical conductivity, are examined, showcasing the impact of doping. Energy gap values highlight the diverse electronic characteristics of the nanotubes. PDOS analysis provides insights into the contribution of atoms to molecular orbitals. UV-Vis absorption spectra unravel the optical transitions, showcasing the influence of nanotube size, dopant type, and location. Hydrogen storage capabilities are explored, with suitable adsorption energies indicating favorable hydrogen adsorption. The desorption temperatures for hydrogen release vary across configurations, with notable enhancements in specific doped DWNT-C variants, suggesting potential applications in high-temperature hydrogen release. Overall, this comprehensive investigation provides valuable insights into the structural, electronic, optical, and hydrogen storage properties of BN and C nanotubes, laying the foundation for tailored applications in electronics and energy storage.

Electronic and optical properties of chemically modified 2D GaAs nanoribbons

We employed density functional theory calculations to investigate the electronic and optical characteristics of finite GaAs nanoribbons (NRs). Our study encompasses chemical alterations including doping, functionalization, and complete passivation, aimed at tailoring NR properties. The structural stability of these NRs was affirmed by detecting real vibrational frequencies in infrared spectra, indicating dynamical stability. Positive binding energies further corroborated the robust formation of NRs. Analysis of doped GaAs nanoribbons revealed a diverse range of energy gaps (approximately 2.672 to 5.132 eV). The introduction of F atoms through passivation extended the gap to 5.132 eV, while Cu atoms introduced via edge doping reduced it to 2.672 eV. A density of states analysis indicated that As atom orbitals primarily contributed to occupied molecular orbitals, while Ga atom orbitals significantly influenced unoccupied states. This suggested As atoms as electron donors and Ga atoms as electron acceptors in potential interactions. We investigated excited-state electron-hole interactions through various indices, including electron-hole overlap and charge-transfer length. These insights enriched our understanding of these interactions. Notably, UV-Vis absorption spectra exhibited intriguing phenomena. Doping with Te, Cu, W, and Mo induced redshifts, while functionalization induced red/blue shifts in GaAs-34NR spectra. Passivation, functionalization, and doping collectively enhanced electrical conductivity, highlighting the potential for improving material properties. Among the compounds studied, GaAs-34NR-edg-Cu demonstrated the highest electrical conductivity, while GaAs-34NR displayed the lowest. In summary, our comprehensive investigation offers valuable insights into customizing GaAs nanoribbon characteristics, with promising implications for nanoelectronics and optoelectronics applications.

Quantum DFT methods to explore the interaction of 1-Adamantylamine with pristine, and P, As, Al, and Ga doped BN nanotubes

Nanostructures, nowadays, found growing applications in different scientific and industrial areas. Nano-coins, nanosheets, and nanotubes are used in medical applications as sensors or drug delivery substances. The aim of this study is to explore the adsorption of 1-Adamantylamine drug on the pristine armchair boron nitride nanotubes (BNNTs) with BNNT(5,5), BNNT(6,6), and BNNT(7,7) chirality along with the P, As, Al and Ga-doped BNNTs, using the quantum mechanical density functional methods. Considering the fact that dispersion effects are important in the case of weak Van der Waals interactions, computations have been done using B3LYP hybrid functional with the implementation of the D3(BJ) empirical dispersion correction methods. Quantum theory of atoms in molecules, natural bonding orbitals, and Kohn-Sham orbitals were used to investigate the nature and type of the adsorption process. The results showed that, while the adsorption of 1-Adamantylamine on the outer surface of pristine BNNT is physical in nature, doping can improve the ability of detracted BN to adsorb the drug through chemical bonds. Also, it was found that, by increasing the radius of the BNNT the adsorption energy was decreased. In conclusion, results of the present work suggest that, Ga doped nanotube, due the chemisorption, is not an ideal nanotube in drug delivery of 1-Adamantylamine drug, whereas, the other studied cases physiosorbed the drug, and may not have serious problem in release of the 1-Adamantylamine drug.

Zinc oxide nanoclusters and their potential application as CH4 and CO2 gas sensors: Insight from DFT and TD-DFT

We have investigated the adsorption of CH₄ and CO₂ gases on zinc oxide nanoclusters (ZnO NCs) using density functional theory (DFT). It was found that the CH₄ tends to be physically adsorbed on the surface of all the ZnO NCs with adsorption energy in the range -11 to -14 kcal/mol. Even though, the CO₂ is favorably chemisorbed on the Zn₁₂ O₁₂ and Zn₁₅ O₁₅ NCs, with adsorption energy about -38 kcal/mol at B3LYP/6-311G(d,p) level of theory. When the CH₄ and CO₂ gases are adsorbed on the ZnO NCs, their electrical conductivities are decreased, and thus the studied ZnO NCs do not generate an electrical signal in the presence of CH₄ and CO₂ gases. Interestingly, both pure and gas adsorbed Zn₂₂ O₂₂ NC exhibited more favorable electronic and reactive properties than other NCs. Comparison of the structural, electronic, and optical data predicted by DFT/B3LYP and TD-DFT/CAM-B3LYP calculations with those experimentally obtained show good agreement.

Half Metallic Ferromagnetism and Transport Properties of Zinc Chalcogenides ZnX2Se4 (X = Ti, V, Cr) for Spintronic Applications

In ferromagnetic semiconductors, the coupling of magnetic ordering with semiconductor character accelerates the quantum computing. The structural stability, Curie temperature (T_c), spin polarization, half magnetic ferromagnetism and transport properties of ZnX₂Se₄ (X = Ti, V, Cr) chalcogenides for spintronic and thermoelectric applications are studied here by density functional theory (DFT). The highest value of T_c is perceived for ZnCr₂Se₄. The band structures in both spin channels confirmed half metallic ferromagnetic behavior, which is approved by integer magnetic moments (2, 3, 4) μ_B of Ti, V and Cr based spinels. The HM behavior is further measured by computing crystal field energy ΔE_crystal, exchange energies Δ_x(d), Δ_x (pd) and exchange constants (N_oα and N_oβ). The thermoelectric properties are addressed in terms of electrical conductivity, thermal conductivity, Seebeck coefficient and power factor in within a temperature range 0-400 K. The positive Seebeck coefficient shows p-type character and the PF is highest for ZnTi2Se4 (1.2 × 10¹¹ W/mK²) among studied compounds.

DFT study of the influence of impurities on the structural, electronic, optoelectronic, and nonlinear optical properties of graphene nanosheet functionalized by the carboxyl group -COOH

In this work, we propose a modified model of graphene oxide nanosheet (GON), based on the Lerf-Klinowski model, through which we attach a carboxyl group (GON-COOH) to the non-equivalent C atom of coronene-based graphene oxide with formation of sp3-like orbital bond. Beryllium, boron, nitrogen, oxygen, and fluorine atoms are integrated into the GON at identical sites in order to study their impact on the physical and chemical properties of GON. Our aim is to propose new efficient materials for applications in optoelectronics and nonlinear optics (NLO). Chemical reactivity and structural, optical, and nonlinear optical properties of GON and its derivatives GON-X (X: Be, B, N, O, and F atoms) were investigated by using the density functional theory (DFT) at the B3LYP-D3/6-31+G(d,p) level of theory. According to the results obtained, the binding energy per atom of GON compound decreases slightly with addition of atoms of the second period elements of the periodic table. The GON-F compound exhibits the smallest value of gap energy compared to other studied compounds and can then be considered a proficient candidate for photovoltaic applications. In regard to NLO properties, we found that the studied models of GON compound theoretically exhibit a larger value of the first static hyperpolarizability than urea, the reference compound for NLO properties.