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The detection of toxic molecules has gained imperial attention to protect living organisms and their environment. The broadly explored sensor behaviour of triazine-based C3N4 reveals their ultra-high sensitivity towards numerous toxic molecules e.g., chemical welfare agents. However, another potential analogue of C3N4 composed of heptazine exhibits remarkable electrical and optical properties but has not been much explored in sensor technology, especially for toxic pollutants. Keeping this in mind, the sensing performance of heptazine-based g-C3N4 is explored for the detection of toxic amides by using First Principles calculations. In this context, acryloyl amide (C2H3CONH2), acryloyl chloride (C2H3COCl), fluoroacetic acid (C2H3FCOOH), flouroaceta amide (C2H2FONH2), flouroacetyl chloride (C2H2FOCl) are selected as toxic pollutants; herein, for the ease of understanding, these molecules are represented as AAM, ACl, FAAc, FAA, & FACl, respectively. The electrochemical sensitivity of g-C3N4 is determined via geometric, energetic, and electronic properties analysis, whereas the photochemical sensitivity is explored by UV–Vis absorption analysis based on TD-DFT calculations. The interaction energies of studied molecules on C3N4 range between − 9.09 and - 23.39 kcal/mol depending upon the type of interactions e.g., hydrogen bonding or dispersion, which are explained on the basis of Symmetry Adopted Perturbation Theory, Non-Covalent Interaction Index, and Quantum Theory of Atoms in Molecules analyses. The density of State analysis, Frontier Molecular Orbitals and NBO charge transfer characterized that the electronic behaviour of g-C3N4 can be an effective sensor material with a semiconducting nature and significant charge transfer. Lastly, UV–Vis absorption analysis confirms the photosensitivity of g-C3N4 upon interaction with toxic molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six new anthracene based novel D–π–A organic dyes have been designed for DSSCs. • Substitution of –NO 2 and –CN (as donors) and –NH 2 and –N(CH 3) 2 (as acceptors) on 9,10-(bis-4-phenylazenyl)anthracene increases its light harvesting efficiency. • The dye bearing –N(CH 3) 2 (donor) and –NO 2 (acceptor) shows the greater bathochromic shift and broader absorption. • The greater charge transfer and highest λ max (994 nm) is also achieved for the same dye. The rational design of dyes for Dye-sensitized solar cells (DSSC) is challenging not only because the dye should absorb in the visible region but also have a favorable alignment with the semiconductor material. Dye sensitized solar cells (DSSCs) with donor-pi-acceptor (D-π-A) organic dyes have received significant interest by the scientific community since last few decades. In the present research work, six dyes (A1-A6) are designed based on 9,10-(bis-4-phenylazenyl)anthracene (R) skeleton by placing substituents on this scaffold. Density functional theory (DFT) and time dependent-DFT (TD-DFT) methods are used to theoretically investigate the optoelectronic properties of these dyes in order to study their potential for DSSCs application. It is also observed that the functionalization of reference compounds with different donor and acceptor groups increases electron injection and internal charge transfer (ICT) in the dye. The results of frontier molecular orbitals (FMO) indicate that the energy gap (E H-L) in A1-A6 is smaller than the reference compound. Among all the proposed dyes, A5 (the dye molecule with the largest number of donor moieties) showed the lowest band gap of 1.06 eV with a maximum absorption wavelength (λ max) value of 994 nm. Different parameters such as light harvesting efficiency (LHE), the free injection energy (ΔG inject), the dye regeneration energy (ΔG reg), open circuit voltage (V oc), reorganization energy (λ total), and excited state energy (τ) are also calculated. TDM analysis are also computed for all the proposed dyes from A1 to A5 and reference compound in order to understand the electronic excitation process. The theoretically calculated values of chemical hardness (η), and chemical potential (μ) suggest that changing the donor and acceptor groups on R compound can change the conductivity and ICT of dyes effectively. The dye A5 shows the lowest value for V oc i.e., 0.08 eV, which is sufficient for spontaneous transfer of electron from the LUMO of the dye to TiO 2 semiconductor. These results reveal that by modifying the donor and acceptor groups, the photovoltaic properties of the molecules can be enhanced. This theoretical work may provide a new path for experimentalists to synthesize these dyes for high performance DSSCs. [ABSTRACT FROM AUTHOR]

The desirability of the high nonlinear response of two-dimensional (2D) materials for electronics and optoelectronic devices drove us to investigate the nonlinear optical (NLO) behavior of alkali metal atom (AA) doped lithiated boron-containing hexahydroxy-triphenylene (LiBHHTP). In this context, the geometric, electronic, optical, and NLO properties are investigated. The doped AA atoms including Li, Na, and K preferably interact via the oxygen atoms of the LiBHHTP surface. The stability of the doped complexes is revealed by the interaction energies (E int), which are −22.90, −16.10, and −16.52 kcal/mol for Li@LiBHHTP, Na@LiBHHTP, and K@LiBHHTP complexes, respectively. The alterations in the electronic behavior of LiBHHTP are observed upon doping with alkali atoms via Frontier Molecular Orbital (FMO), Natural Bond Orbital (NBO), and the Density of State (DOS) analyses. The FMO analysis reveals that these complexes are electride in nature with absorption transparency in the UV–Vis range. Finally, the NLO behavior of designed complexes is evaluated through static and dynamic hyperpolarizabilities. Among reported complexes, K@LiBHHTP exhibits significantly large static hyperpolarizability (βₒ), 2.24 × 105 au. The dynamic NLO response of doped LiBHHTP complexes is also high, where the values are ranged in between 3.67 × 105 and 6.04 × 108 au at 1064 nm. This article not only highlights the effects of alkali atom doping on the NLO behavior of materials but also presents the first Lithiated boron-containing triphenylene as a next-generation optoelectronic material. [Display omitted] [ABSTRACT FROM AUTHOR]