Optical and morphological properties of Curcuma longa dye for dye-sensitized solar cells

Experimental optical properties explained by density functional theory of the natural red algae for dye-sensitized solar cells application

The present study investigates the usage of a novel natural dye derived from red algae of Morocco in dye-sensitized solar cells (DSSCs) for the first time. The main pigments responsible for sensitizing the semiconductor TiO2 coatings in the red algae were identified as phycoerythrin, carotenoid, and chlorophyll. The efficiency of a DSSC made from red algae was compared to that of a solar cell made from chlorophyll alone. The photovoltaic performance of the DSSC was evaluated through photocurrent density to photovoltage (J-V) characteristic analysis, and the efficiency was found to be 0.93%. To gain insights into its behavior, the absorbance and photoluminescence in a broad range were studied. Both absorbance and photoluminescence exhibited a broad-spectrum range. Additionally, electronic properties, such as HOMO, LUMO, energy gap, and chemical reactivity parameters, were studied using density functional theory (DFT) calculations.

Topography and Nonlinear Optical Properties of Thin Films Containing Iodide-Based Hybrid Perovskites

This article covers selected properties of organic-inorganic thin films of hybrid perovskites with the summary formulas CH3NH3MI3, where M = Pb, Cd, Ge, Sn, Zn. The paper discusses not only the history, general structure, applications of perovskites and the basics of the theory of nonlinear optics, but also the results of experimental research on their structural, spectroscopic, and nonlinear optical properties. The samples used in all presented studies were prepared in the physical vapor deposition process by using co-deposition from two independent thermal sources containing the organic and inorganic parts of individual perovskites. Ultimately, thin layers with a thickness of the order of nanometers were obtained on glass and crystalline substrates. Their structural properties were characterized by atomic force microscopy imaging. Spectroscopic tests were used to confirm the tested films' transmission quality and determine previously unknown physical parameters, such as the absorption coefficient and refractive index. Experimental results of the nonlinear optical properties were obtained by studying the second and third harmonic generation processes and using initial sample polarization in the so-called Corona poling process. The obtained experimental results allowed us to determine the second- and third-order nonlinear optical susceptibility of the tested materials.

Synergetic effect of Leucophyllum frutescens and Ehretia microphylla dyes in enhancing the photovoltaic performance of dye-sensitized solar cells

The use of new natural dyes derived from Leucophyllum frutescens and Ehretia microphylla as well as their combination in dye-sensitized solar cells (DSSCs) has been explored for the first time in the current work. The primary pigments that sensitize the semiconductor TiO₂ films were found to be carotenoid, anthocyanin, and chlorophyll. Pigments from Leucophyllum frutescens and Ehretia microphylla were designated as LF and EM, and their mixture blended at volume percent of 50:50, 75:25, and 25:75 were labeled as LE1, LE2, and LE3, respectively. The absorption range, emission intensities, and the functional groups of the dyes and dye-loaded TiO₂ photo-anode films were analyzed using ultraviolet-visible, photoluminescence and Fourier transform infrared spectroscopy. The surface morphology of bare and sensitized TiO₂ films was identified through scanning electron microscopy (SEM). To evaluate the photovoltaic performance of the fabricated devices, the current-voltage characteristics, electrochemical impedance spectroscopy analysis and incident photon-to-current conversion efficiency measurements were performed. The study found that the co-sensitized cell LE2 outperformed both single and mixed dye-based cells, achieving a maximum conversion efficiency of 1.33% with a V_oc of 516 mV and a J_sc of 2.55 mA cm^-2. This synergetic effect of natural dyes proved the superior performance of DSSCs with co-sensitization.

Generation of red light with intense photoluminescence assisted by Forster resonance energy transfer from Znq2 and DCM thin films

In this work, a novel experimental investigation of photoluminescence properties of Znq₂ thin films co-doped with different concentrations of DCM were performed. The thin films were successfully deposited on glass substrates with different compositions, under high vacuum, by using the vacuum evaporation technique. For all compositions, the photoluminescence was measured at room temperature and also at low temperature in a wide range from 77 to 300 K with a step of 25 K in a high vacuum. The lifetime of the sample studied in real time was also measured using the decay time technique. The results obtained confirm that the doping influences the intensity of the DCM photoluminescence and also shows a complete energy transfer occurred from Znq₂ to DCM which may have shifted the photoluminescence peak from Znq₂ to the orange wavelength region which is related to DCM. The lifetime of the sample studied in real time was about 4.47 ns for Znq₂ and while all the other samples showed two decay time components. As a result, the doping influences the optical properties of Znq₂ and makes it a potential candidate for optoelectronic applications.