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Water is a vital ingredient for life, but its quality is constantly deteriorating due to textile effluent carrying harmful dyes. Photodegradation is a highly effective process for breaking down dye using solar spectrum. In the current work, hydrothermal approach was used to designed pure tungsten disulfide and doped tungsten disulfide with differnet concentration (5, 10, and 15%) for photocatalytic degradation of methylene voilet. Different instrumental analyses were conducted to measure the physichemical and optical properties of the fabricated pure and doped materials. The photocatalytic behavior of the WS2, 5% doped WS2, 10% doped WS2 and 15% doped WS2 was noted after 0, 15, 30, 45, 60, and 75 min under sunlight. The removal of methyl violet (MV) by using pristine WS2, 5% doped WS2, 10% doped WS2 was about 51, 70, and 80%, respectively. The maximum degradation of methylene violet was given by 15% doped WS2 about 90% after 75 min under sunlight. The 15% doping of the Sm reduced the band gap that can effectively absorb the greater extent of the solar spectrum and degrade the methyl violet dye. The fabricated optimized doped photocatalyst can also be employed in other application such as batteries, drug delivery, and water splitting. [ABSTRACT FROM AUTHOR]

Carboxylic acid supramolecular synthon exhibited dimer or catemer motifs in the crystal lattice depend on the substituent and other functional groups present in the structure. In general, presence of other competing functional groups produced catemer motifs, whereas unsubstituted acids showed dimer. In this manuscript, we have synthesized a new aryl ether amine-based Schiff base with carboxylic acid functionality (1) and demonstrated polymorphic structure via catemer (1a) and dimer (1 b) motifs in the solid state. In both the structure, carboxylic acid group adopted different orientation in the crystal lattice. The different H-bonding lead to modulation of optical properties that was further supported highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) calculation. Further the stability calculation indicates that dimer (1 b) structure was more stable by 8.54 kcal/mole relative to catemer (1a) motifs. Further, the supramolecular interactions in catemer (1a) and dimer (1 b) motifs was studied by Hirshfeld surface and fingerprint plots to gain insight and compare the different functional groups contribution for intermolecular interactions in the polymorphic crystals which clearly showed different intermolecular interactions in polymorphs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Perovskite LaFeO 3 , spinel NiFe 2 O 4 and their composites were synthesized using the normal microemulsion process. • The degradation of methylene blue in the composite (92%) was significantly greater than that of lanthanum and nickel ferrite due to suitable band gap value. • Light-induced electron/hole recombination from the valence band to the conduction band may be impeded in the composite which is responsible for the higher activity of this material. • This inhibition in recombination of electrons/holes pair was also confirmed by the PL analysis. Most dyes are carcinogenic; thus, they must be removed from the water to save aquatic and human life. Among the various methods, the photocatalytic degradation of dyes is attracting much attention due to the easy strategy driven by the solar light. Herein, we report the fabrication of nickel ferrite (NiFO), lanthanum ferrite (LFO) and their composite are utilized as a light-driven catalyst for the deprivation of significant commercial dyes. The straightforward microemulsion method is used to produce both pure ferrite materials and their composite counterparts. The phases of the synthesized materials were verified through XRD analysis while scanning electron microscopy was employed to examine their morphology. The average crystallite size of the LFO, NiFO and their composite was 53, 62 and 42 nm, respectively. The elemental composition of the pristine and composite was confirmed by the energy dispersive spectroscopic analysis, indicating no other impurity in the materials. The optical properties are analyzed via UV visible and photoluminescence to measure the band gap value of 2.05, 1.73 and 1.9 eV for LFO, NiFO and their composite, respectively. It is observed that the LaFeO 3 /NiFe 2 O 4 has the highest photodegradation efficiency (92 %) as compared to the LFO (LaFeO 3) and NiFO (NiFe 2 O 4). The composite material also showed excellent reusability as well as good stability. It was also confirmed that OH radicals are the major contributor toward the dye degradation, as confirmed by the scavenger tests. The higher mineralization of methylene blue in the occurrence of composite as a catalyst may cause rapid charge transfers, as confirmed by EIS, and it may stop the recombination of electrons/hole pairs due to suitable band alignments. [ABSTRACT FROM AUTHOR]

In the present investigation, we use a dual computational approach (at single molecular and solid-state levels) to explore the optoelectronic and nonlinear optical (NLO) properties of cross-shaped derivatives. The solid-state electronic band structures of the compounds 1–3 (the derivatives of tetracarboxylic acid in cross-shaped having the core of benzene (1), pyrazinoquinoxaline (2), and tetrathiafulvalene (3)) are calculated. The calculated band gaps for compounds 1–2 are found to be direct bad gaps and compound 3 to be indirect bad gap with energy gaps of 2.749, 1.765, and 0.875 eV, respectively. The important optical properties including refractive index, absorption coefficients, loss functions, and extinction coefficient of these semiconductors are calculated at bulk level to seek their potential applications as efficient optoelectronic materials. Additionally, we use the Lorentz approximation to calculate the third-order NLO susceptibilities of compounds 1–3 using the molecular hyperpolarizability and solid-state parameters. The calculated third-order NLO susceptibilities of compounds 1–3 are found to be 6.92 × 10−12, 64.0 × 10−12, and 26.3 × 10−12 esu, respectively. Thus, the present study not only provides a way to connect the calculated third-order molecular NLO polarizability to NLO susceptibilities for compounds 1–3 through Lorentz approximation but also highlights the importance of central core modifications on their NLO susceptibilities. [ABSTRACT FROM AUTHOR]

Highlights: [•] NiO nanoparticles have been prepared by microwave assisted method at different pH. [•] Monophasic and highly crystalline NiO nanoparticles were established by using sophisticated techniques. [•] Optical band gap increases on increasing the amount of NaOH. [•] High surface areas in the range of 33.1–39.8m2/g have been achieved. [ABSTRACT FROM AUTHOR]

The structures of 5,5′-bis(naphth-2-yl)- 2,2′-bithiophene (NaT2), 5,5″-bis(naphth-2-yl)-2,2′:5′,2′-terthiophene (NaT3), 5,5‴-bis(naphth-2-yl)-2,2′:5′,2″:5″,2‴-tetrathiophene (NaT4), 5,5″″-bis(naphth-2-yl)-2,2′:5′,2″:5″,2‴:5‴,2″″-quinquethiophene (NaT5) and 5,5′″″-bis(naphth-2-yl)-2,2′:5′,2″:5″,2‴:5‴,2″″:5″″,2′″″-sexithiophene (NaT6) have been optimized at PBE1PBE/6-31G* level of theory. By increasing the chain length (thiophene units) energy gap decreases. The hole reorganization energy also decreases from NaT2-NaT6. We have observed that mobility of NaT5 and NaT6 can be enhanced by minimizing the polarization and relaxation. The end-capped naphthyl groups have been rotated from 0°-60° in the case study of NaT2, it was found that hole reorganization energy increases with the increment in angle. Furthermore the charge transport properties of 5,5′-bis(thionaphth-2-yl)-2,2′-bithiophene (TNT2), 5,5″-bis(thionaphth-2-yl)-2,2′:5′,2″-terthiophene (TNT3), and 5,5‴-bis(thionaphth-2-yl)-2,2′:5′,2″:5″,2‴-quaterthiophene (TNT4) have been investigated at the same level of theory. It has been studied that cis isomers have higher hole reorganization energies as compared to trans ones thus these isomers would diminish the mobility. [ABSTRACT FROM AUTHOR]

Recently, the graphite based heterogeneous photocatalysts has attained tremendous research attention in various environmental applications. Among them, the graphitic carbon nitride (g-C 3 N 4) is categorized as a unique solar active particle with its outstanding intrinsic properties i.e., adequate band configuration, excellent light absorptivity and thermo-physical durability, which make it highly useful and reliable for revenue transformation and ecological concerns. Considering the intrinsic potential of g-C 3 N 4 in photocatalysis, so far, no report has been done in literature for its extraordinary configuration, morphological characteristics and perspective tuning for said applications. To overcome this research gap, our primary emphasis of this review regarding photocatalysis is to provide layout as well as the advancement of visible-light-fueled materials as highly stabilized and extremely effective ones for pragmatic implementation. Thus, this existing comprehensive assessment conducts a systematic survey over visible light driven non-metal novel g-C 3 N 4. The major advancement of this evaluation is the fabrication of well-designed nanosized g-C 3 N 4 photocatalysts with unique configurable frameworks and compositions. Furthermore, alternative techniques in order to customize the analogue band configuration and noticeable cultivation such as metal (cation), nonmetal (anion) doping, worthy metal activating, and alloy initiation with certain semiconductors are discussed in detail. In addition to this, g-C 3 N 4 photocatalytic functionalities towards photocatalytic hydrogen evolution, CO 2 photoreduction, biological metal ions deterioration as well as bacterial sanitization are also presented and discussed in detail. Therefore, we believe that such a pivotal compact assessment can provide a roadmap in several perspectives on the currently underway obstacles in the innovation of effective g-C 3 N 4 catalytic design processes. Moreover, this critical assessment will ultimately serve as a useful supplement in the research area of g-C 3 N 4 nanosized photocatalysts and for the researchers working on its key aspects in diverse range of natural, chemistry, engineering and environmental applications. • Graphitic carbon nitride (g-C 3 N 4) is a metal-free sustainable photocatalyst with a band gap of 2.7 eV. • G-C 3 N 4 has improved light absorption performance as well as electronic features. • Multiple synthetic approaches are being used with g-C 3 N 4 to improve its photocatalytic capabilities. • Metals/nonmetals doping, activation, and alloy formation are employed for g-C 3 N 4 nanocomposites. • Our review includes the latest current g-C 3 N 4 nanocomposites and their photocatalytic implications. [ABSTRACT FROM AUTHOR]

• DFT and molecular dynamic studies of liver cirrhosis biomarker volatiles. • PTN_Ga@AlNNT and LMN_Ga@AlNNT possessed the highest and least energy gap. • PTN_Ga@AlNNT have the highest fraction of electronic transfer for the studied systems. • In@ AINNT have the highest stabilization energy. • Molecular dynamic show that the nanomaterials induced conformational changes. In the realm of scientific curiosity, the quest to develop groundbreaking biosensor technology and materials that cater to the urgent societal demands in healthcare, environment, food safety, and beyond has reached unprecedented heights. In this study, we delve into the captivating world of cutting-edge research, harnessing the power of density functional theory (DFT) at the B3LYP-GD3(BJ)/def2-SVP level of theory to investigate the adsorption, conductivity, reactivity, and dynamical stability of biomarker volatiles of liver cirrhosis: limonene (LMN), methanol (MTN), and pentanone (PTN) on aluminum nitride nanotube (AlNNT) and its metals doped Indium (In) and Gallium (Ga) designed surfaces. From the evolution in band gap analysis, PTN_Ga@AlNNT was noticed to have obtained least energy gap of 3.035 eV whereas, LMN_Ga@AlNNT system had the highest energy gap of 4.330 eV. The calculated fraction of electronic transfer for the studied systems were observed as thus; −2.48936, −0.798342 and −6.321428571 for LMN_Ga@AlNNT, MTN_Ga@AlNNT and PTN_Ga@AlNNT respectively. The perturbation energy analysis presents an increasing stabilization energy of Aluminum nanotube doped with Gallium (Ga) and indium (In) surface to followed the trend; In@ AINNT > Ga@ AINNT. Results from the Molecular Dynamic simulation suggest that the nanomaterials studied induced conformational changes in all six complexes during the simulation, as evidenced by the changes in energy and temperature. Also, from the UV– Vis analysis, the excited states in all three instances are single-A states, which implies they have spin quantum number S = 0. We hope this research work will contribute to the development efficient biosensor materials. [ABSTRACT FROM AUTHOR]

• DFT study for the detection and adsorption of buprofezin insecticide. • Heteroatoms doped on a Pt-coordinated graphitic carbon nitride (Pt@C 3 N 4). • Negative adsorption energies observed for interacting surfaces doped with B, N, P, S and Si. • Strong chemisorption was observed in the BPF_S_Pt@C 3 N 4 which had highest adsorption. • Heteroatom doping of Pt@C 3 N 4 materials for maintaining environmental sensing applications. As global agriculture seeks to reduce the reliance on conventional insecticides with potentially harmful effects for modern agriculture and insect-pest control practices, we improve the appeal of buprofezin as a safe and sustainable pest control option. Herein, we conducted theoretical investigations to explore the adsorption efficacy, sensibility, and reactivity of heteroatoms (B, N, P, S and Si) doped on a custom-engineered platinum-encapsulated graphitic carbon nitride (Pt@C 3 N 4) as enhanced sensor materials for the adsorption of buprofezin (BPF) insecticide within the framework of density functional theory (DFT) computation at the B3LYP-GD3BJ/def2svp level of theory. Consequently, the notable variations observed in the energy gap of the studied surfaces when interacted with buprofezin accounted for the reactivity, stability, conductivity, work function, and overall adsorption potentials of the sensor material which projects the doped surfaces as a suitable sensor material for sensing buprofezin (BPF). More so, the negative adsorption energies observed for interacting surfaces doped with B, N, P, S and Si suggest the strong propensity to trap buprofezin molecule better as a considerably strong chemisorption was observed especially in the BPF_S_Pt@C 3 N 4 which had highest adsorption of -51.355 kcal/mol. With firm conviction, this research study will be helpful and provide useful knowledge as background research for future study and experimental researchers to uncover the potentials in heteroatom doping of Pt@C 3 N 4 materials for maintaining ecological balance and environmental sensing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, metal–semiconductor–metal (MSM) ZnO-based Schottky barrier diodes (SBDs) were fabricated on the basis of titanium-doped tin–zinc oxide (SZT) films by sol–gel spin coating. Au/(Sn:Zn):Ti:ZnO/p-Si/Au SBDs with varying wt% of Ti were then fabricated. The effects of Ti doping concentration on the structural, optical, and electrical properties were studied. The doped films are consistently homogeneous with increasing Ti content. The optical measurements confirm high film transmittance in the visible spectrum. The optical band gap energy of the SZT films was around 3.90 ± 0.02 eV. The current–voltage, impedance spectroscopic, and photoresponse measurements showed that Ti-doping improved the performance of the devices by increasing the barrier heights and hence the rectification ratios of the devices. The reduction in ideality factors and series resistances implies that Ti doping improves the devices towards near-ideal behavior by passivating interface states. • Titanium and tin co-doped Au/(Sn:Zn):Ti:ZnO/p-Si/Au Schottky diodes. • %wt Ti varied from 0 to 40%. • Ti doping enhances electrical properties and optoelectronic performance. • The presence of Ti drives the devices towards near-ideal behavior. • The spectroscopic characteristics and performance of the films are improved. [ABSTRACT FROM AUTHOR]

• Confirmation and preparation of new funcional single-chain polymer. • Summarizes electro-optic properties of single-chain polymer composites doped nanographene. • Discusses optic properties of single-chain polymer composites doped Sudan III. • Reveals thermal behaviors of both composites doped nanographene and Sudan III. The synthesis of poly[4-(4-vinylbenzyl)oxy)phthalonitrile-co-styrene] [P(VBOPN5 %-co-St)] was carried out by free radical polymerisation at 60 °C. The successful formation of a green coloured single-chain polymer molecule with the formation of cobalt phthalocyanine (SCP-CoPc) was performed at 140–150 °C in the presence of dilute cyclohexanol. The characterization of SCP-CoPc was confirmed by FT-IR and UV/vis spectroscopic techniques. The absorption filtration process of the SCP-CoPc polymer/Sudan III composite was investigated. The introduction of Sudan III into the SCP-CoPc polymer matric strongly affected the optical transmission spectrum of the composite films. The optical transmission measurements of the SCP-CoPc/Sudan III thin film show a high absorption in the visible region (400–800 nm). In the SCP-CoPc/Sudan III composites, the optical band gaps (Eg1 and Eg2) of each of its components has changed significantly. The Eg1 and Eg2 were found to be between 1.90 and 2.83 eV, respectively. Depending on the sudan III content, a wide range from 600 nm to 730 nm indicates complete absorption filtration. The dc electrical conductivity and dielectric behavior of the SCP-CoPc/Nanografene (NG) 6 wt% nanocomposite increased with increasing temperature. From the dc conductivity plot, the Ea values of I. and II. regions were found to be 0.75 eV and 0.27 eV, respectively and it was found that the calculated activation energy obeyed the Arrhenius relationship. The refractive index and the optical permittivity of SCP-CoPc/NG 6 wt% have been estimated. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] TiO 2 nanostructures have been one of the most explored metal oxides photocatalysts to apply for environmental remediation. However, its wide band gap results in the underutilization of sunlight for degradation of pollutants. In order to overcome this handicap, the synthesis of TiO 2 -based composite has brought extraordinary materials. In this study, we design and prepare TiO 2 /Nb 2 O 5 heterostructures with different molar ratios by using peroxotitanium and peroxoniobium complex as precursors in aqueous solution. The TiO 2 exists in the form of anatase while Nb 2 O 5 is amorphous in the composite, leading to a special crystalline TiO 2 /amorphous Nb 2 O 5 heterostructures. In particular, Nb element is also doped and Ti3+ ions are formed in the TiO 2 lattice, leading to a reduced band gap. The unique TiO 2 /0.25Nb 2 O 5 (Ti:Nb = 2:1) heterostructures can effectively suppress the recombination of photogenerated electrons and holes, and facilitate the charge transfer, resulting in the optimum photocatalytic performance. The nitrogen oxide removal efficiency by TiO 2 /0.25Nb 2 O 5 is 77.23% in visible light, which is 3.8-folds and 7.0-folds higher than pure TiO 2 and Nb 2 O 5. Photocatalytic degradation of acetaminophen by TiO 2 /0.25Nb 2 O 5 is 90.6% in visible light, which is approximately 2.5-folds higher than pure TiO 2 and Nb 2 O 5. [ABSTRACT FROM AUTHOR]

• Tricyclic 1 H -benzo[ f ]chromene-2-carbothioamides were synthesized as potential anticancer agents. • The cytotoxic activity was tested against MCF-7, HepG-2 and PC-3 cell lines. • Various molecular descriptors, frontier molecular orbitals, Mulliken analysis and electronic properties were studied. • The energy gaps, reactivity descriptors values and molecular docking of the target compounds were discuses. Reaction of 7‑methoxy-2-naphthol with appropriate aromatic aldehydes and 2-cyano-ethanethioamide provided the corresponding 3-amino-1-aryl-9‑methoxy-1 H -benzo[ f ]chromene-2-carbothioamide. The structures of these compounds were established on the basis of IR, 1H NMR, 13C NMR, MS data and elemental analysis. Furthermore, the anti-proliferative properties were evaluated against the human cancer cell lines MCF-7, HepG-2 and PC-3 in comparison to the positive controls Vinblastine and Doxorubicin, employing the viability assay. The obtained results confirmed that some of the tested molecules revealed strong and selective cytotoxic activities against the three cancer cell lines. Moreover, various molecular descriptors, frontier molecular orbitals (FMO), Mulliken analysis and electronic properties were studied to probe the biological activity behavior of the synthesized 1 H -benzo[ f ]chromene-2-carbothioamide derivatives. The effect of electron withdrawing groups (EWGs) and electron donating groups (EDGs) was also explored on the structural parameters and electronic nature of compounds. The energy gaps, reactivity descriptors values and molecular docking studies exhibited that some 1 H -benzo[ f ]chromene-2-carbothioamide derivatives would be active biological compounds. [ABSTRACT FROM AUTHOR]

• Quantum chemical calculations on performed on few oxazole compounds using. • Band gap, local softness values have been procured for different solvents. • Chemical structure and reactivity, topological analyses were carried out. • Solvation effects on UV–Visible spectrum were inspected using the TD-DFT system. • Optical properties and charge transport nature of the compounds were explored. The ground state geometries of oxazole compounds, i.e. , 3,5-Bis-(4-chloro-phenyl)-7a-methyl-dihydro-oxazolo[3,4-c]oxazole (Compound 1) and 3,5-Bis-(4-methoxy-phenyl)-7a-methyl-dihydro-oxazolo[3,4-c]oxazole (Compound 2) were optimized using Density functional theory employing B3LYP/6-31G++ level for comparing the geometric parameters (torsion angles, bond angles & bond lengths) with the X-ray crystallographic information. We explored the charge transport nature, wave functional properties, optical and electronic properties of both the oxazoles. The computed geometric parameters are rational to the experimental data. The time-domain TD - B3LYP/6-31G++ & the B3LYP/6-31G++ levels were used to reveal the electronic characteristics and absorption wavelength. Intra-molecular charge transfer was perceived in studied compounds. The IEFPCM (Integral Equation Formalism Polarizable Continuum Model) model was used to calculate the solvation UV spectrum. The effect of various solvents (acetone, acetonitrile, DMF(Dimethylformamide), DMSO (Dimethyl sulfoxide) and methanol) was examined on the excitation energies but solvent polarity has no discernible impact on the wavelengths of absorption. From HOMO-LUMO (Highest Occupied Molecular Orbital – Lowest Unoccupied Molecular Orbital) orbitals with various solvent molecules, band gap energies with the solvation effect are determined. Additionally, through the use of topological analytics like RDG (Reduced Density Gradient), ELF (Electron Localisation Function) & LOL (Localised Orbital Locator), the energy concentration of electrons was elucidated. Furthermore, the outcome of electron-donating cluster (–OCH 3) and electron-withdrawing cluster (–Cl) was studied on open-circuit voltage, bandgap alignment, electron coupling constants, excitons dissociation values, ΔGinject – electron injection, LHE-Light Harvesting Efficiency and electron coupling constants (|V RP |). [ABSTRACT FROM AUTHOR]

Large size single crystals of Diiodo-bis(carbamide)-zinc(II) [ZnI 2 . 2[CO(NH 2 ) 2 ] were grown successfully for the first time by slow evaporation techniques at room temperature within the evaporation time of two weeks. The single phase and high crystalline nature of the grown crystals was confirmed by X-ray diffraction analysis. Quantum chemically the geometrical parameters were found in good correlation with experimental values calculated at B3LYP/6-31G* (LANL2DZ), B2LYPD/6-31G* (LANL2DZ), M062X/6-31G* (LANL2DZ) and MP2/6-31G* (LANL2DZ) level of theories. Additionally, the experimental vibrational modes also have shown a good agreement with calculated ones. The optical transparency and band gap were calculated and found to be ∼80% and 4.706 eV, respectively. The calculated value of HOMO-LUMO gap was found in correlation with experimental energy gap. The electronic properties were investigated by shedding light on the frontier molecular orbitals, partial density of states (PDOS), and total density of states (TDOS). The mechanical and dielectric studies show that the grown crystals possess quite good mechanical strength and dielectric constant. The dielectric loss revealed that the grown crystal contains low defects. The total ac electrical conductivity was increased with frequency and the frequency components confirm the sudden hoping mechanism in the grown crystal. [ABSTRACT FROM AUTHOR]

• A carbon abundant 2‐D structure material 5,8-dibromoisoquinoline (BQ) has been integrated as an aromatic organic monomer within carbon nitride (CN) via molecular aggregation process. • The BQ copolymerized CN with distinguish characteristics leads to a significant increment in the applied application. • The copolymerized samples demonstrating narrowed band gap, high surface area, splendid morphology, and wide optical absorbance which enhanced electron transport ability. • The spinal material, i.e., 10BQ/CN exhibited a superior H 2 evolution of ten‐fold higher activity and also photodegradation of RhB under visible light driven. Graphitic carbon nitride, g-C 3 N 4 (CN) is regarded as an excellent metal-free semiconductor known for its potential solar fuel generation and pollutant degradation. In this study, a carbon richer substance, (5,8-dibromoisoquinoline (BQ)) was used to feed its catalytic function through conventional copolymerization (molecular doping) process at 550°C under a nitrogen atmosphere. The incorporation of BQ monomer in the triazine oligomers of CN in turn enhanced the specific surface area, thereby, improving the lifespan of photoexcited charge carriers, decreasing the charge recombination rate, energy bandgap, and altering the optoelectronic characteristics of CN. On average, the rate of hydrogen (H 2) production over-optimized 10BQ/CN was 710.1 µmol/h much superior and 10 times higher than that of pure CN (71.9 µmol/h). Particularly, the kinetics of the photocatalytic degradation of RhB over 10BQ/CN followed pseudo-order kinetics and the rate constant was three times larger than pure CN. Our results illustrate the crucial importance of conjugated monomers in improving photocatalysis process for future energy demand by providing key steps towards sustainable energy production. [Display omitted]. [ABSTRACT FROM AUTHOR]

• Cu 2 FeSnS 4 nanoparticles were produced. • Al/p-Si/Cu 2 FeSnS 4 /Al structures were fabricated. • Optic properties of Al/p-Si/Cu 2 FeSnS 4 /Al structures were investigated. • Electrical properties of Al/p-Si/Cu 2 FeSnS 4 /Al structures were assessed. Cu 2 FeSnS 4 semiconductor used in the preparation of quaternary photodiodes was synthesized using hydrothermal synthesis. The nanoparticles were then spin coated on a silicon substrate. Nanoparticles were characterized using SEM and EDX where nanoparticles in granular form were seen. Optoelectronic properties were assessed using UV spectra throughout which bandgap energies were calculated. The band gap energy of Cu 2 FeSnS 4 semiconductor was found as 1.22 eV. I – V and I – t characteristics illustrate that Al/p-Si/Cu 2 FeSnS 4 /Al heterojunction photodiodes were responsive to daylight and infrared light. Ideality factor, barrier height, saturation current, and photoresponse values were calculated using I - V and I - t data. The ideality factors were calculated as 5.14 and 5.61 for daylight and infrared light (IR) illuminations, respectively. Electrical properties of diodes were checked using C – V and G – V analysis. It was seen that the electrical properties of photodiodes strongly depend on AC signal frequency. Our assessment revealed that frequency related electrical behavior is originated from interface states. [ABSTRACT FROM AUTHOR]