Synthesis, Photophysical and Computational Study of Novel Coumarin-based Organic Dyes

Design of Metal Free Fluorescent Pyridine Dyes Anchored on Cadmium Sulfide Nanowires: Optical, Electrochemical and Photovoltaic Applications

Through a facile two-step synthetic procedure, three metal-free organic dyes having D-π-A kind of structure, belonging to chalcone family have been designed, produced and anchored on one dimensional cadmium sulfide nanowires (1D CdS NWs) to serve as a light energy harvester through dye-sensitized solar cells (DSSC) assembly. In order to anchor dye on CdS NWs nano-network, solution chemistry has been used in an easy and effective manner. The sensitizing capability of synthesized materials has been evaluated using optical and electrochemical studies, density functional theory (DFT) simulations, and photovoltaic performances. In line with a detailed analysis of fabricated Dye sensitized solar cells containing T4PC a photovoltaic efficiency yields 4.35 times (0.487%) more than that of bare CdS NWs (0.112%), while the other devices having T3PC and T2PC have shown 3.0 (0.338%) and 2.40 (0.273%) times greater photovoltaic efficiencies, respectively under standard light illumination. The obtained results offer solid evidence in favour of boosting external quantum efficiency (EQE) and reflect good agreement with the optical studies.

3-(4-Formylphenyl)-triazole functionalized coumarins as violet-blue luminophores and n-type semiconductors: synthesis, photophysical, electrochemical and thermal properties

3-(4-Formylphenyl)-triazole-coumarin hybrid chromophores (FPhTCs) were synthesized in good yields, using a click chemistry protocol, and were also structurally characterized. Their photophysical, electrochemical and thermal properties were measured demonstrating that FPhTCs are luminescent in the blue-violet region of the electromagnetic spectrum, both in solution and the solid state. They showed an electrochemical band-gap values of 2.79 ± 0.08 eV, resistivity values between 10⁴ and 10⁵ Ω cm and are thermally stable up to 225 °C, properties that promise FPhTCs as good candidates for optoelectronic or imaging applications. Their solution and solid state photoluminescent properties are discussed and supported by theoretical calculations.

Synthesis, photophysical, quantum chemical investigation, linear and non-linear optical properties of coumarin derivative: Optoelectronic and optical limiting application

In order to develop a new photostable, light emitting and highly efficient synthesized material to exhibit display property and non-linear optical active materials with good band gap energy, we have synthesized molecule via simple catalytic method. The photophysical property of studied molecule in various organic solvents having different polarity exhibited considerably acceptable results. The results of quantum yield, lifetime and large Stoke shift shows the compound is a good promising candidate for the laser dyes and light emitting diode color filters. The energy band gap was determined by both experimentally and theoretically which is found to be an average of 3.2 eV which is well matched to the semiconducting materials band gap. The non-linear optical absorption properties of the synthesized molecule are dissolved in suitable solvents had been investigated using Z-scan technique. We have determined the sign and magnitude of nonlinear absorption coefficient by the method of open aperture Z-scan setup using an Nd: YAG continuous wave laser at 532 nm. The open aperture Z-scan profiles clearly demonstrate the presence of reverse saturable absorption kind nonlinearity in the investigated compound and are due to the two-photon absorption. Results of the non-linear optical studies confirm that the studied compound is more latent applications for optical limiting in continuous wave regime. Further, the optoelectronic properties were investigated the international commission on illumination, color rendering index, color purity, and correlated color temperature is results of the studied molecule in all studied solvents revels that this compound exhibits blue to cyan color and is suitable for organic light emitting diode which can be preferably used for daylight applications.

Performance Enhancement of Betanin Solar Cells Co-Sensitized with Indigo and Lawsone: A Comparative Study

Co-sensitization is an important strategy toward efficiency enhancement of solar cells by enabling better light harvesting across the solar spectrum. Betanin is a natural dye which absorbs light in the major portion of the incident solar spectrum (green region) and is the most efficient natural pigment used in dye-sensitized solar cells. This study investigates the performance enhancement of a betanin solar cell by co-sensitizing it with two natural pigments which show complementary light absorption, i.e., indigo and lawsone, absorbing in the red and blue regions of the solar spectrum, respectively. The calculated highest occupied molecular orbital and lowest unoccupied molecular orbital energies of the pigment molecules, derived from density functional theory (DFT) simulations, confirmed their optimal alignment with respect to the conduction band energy of the TiO₂ semiconductor and reduction potential energy level of the I^-/I₃ ^- electrolyte, a necessary requirement for optimal device performance. Lawsone solar cells displayed better performance, showing average efficiencies of 0.311 ± 0.034%, compared to indigo solar cells showing efficiencies of 0.060 ± 0.004%. Betanin was co-sensitized with indigo and lawsone, and the performances of the co-sensitized solar cells were compared. The betanin/lawsone co-sensitized solar cell showed a higher average efficiency of 0.793 ± 0.021% compared to 0.655 ± 0.019% obtained for the betanin/indigo co-sensitized solar cell. An 11.7% enhancement in efficiency (with respect to betanin) was observed for the betanin/indigo solar cell, whereas a higher enhancement of 25.5% was observed for the betanin/lawsone solar cell. Electrochemical impedance spectroscopy studies confirmed that the higher efficiency can be attributed to the higher electron lifetime of 313.8 ms in the betanin/lawsone co-sensitized solar cell compared to 291.4 ms in the betanin/indigo solar cell. This is due to the energy levels being more optimally aligned in lawsone compared to that of indigo, as observed in the DFT studies, and the lack of dipole moment in indigo, resulting in more efficient charge separation and charge transfer in lawsone.