Photonic Characteristics of Sepia melanin & Application in Dye-Sensitized Solar Cells (original) (raw)
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Optical and photoelectronic properties of melanin
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Steady-state and time-resolved photoluminescence (PL) spectra of natural and synthetic melanin, as well as melanin composites with surfactant, sodium dodecylbenzenesulfonate, and polymethine dye, astraphloxin, have been studied. The melanin molecules having differently charged peripheral groups with terminal O atoms and OH groups mixed with the negatively charged surfactant or positively charged astraphloxin dye feature new PL spectral bands. The kinetics of PL and time-resolved emission spectra for the melanin and the composites were also investigated and discussed in terms of intermolecular complexation, nanoaggregation and formation of charge-transfer states. The studies are aiming to understand the electronic properties of various melanins, particularly natural ones.
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In the present course of study, deliberate investigation of natural dyes versus synthetic dyes in dye-sensitized solar cells (DSSCs) has been undergone through. Although quoted efficiency values of artificial dyes like N7 dye, black dye and N719 dye etc. is efficiently higher than natural ones such as turmeric, rosella, sweet potato leaf and blue pea etc. Yet the latter meet the fundamental aim of DSSC i.e. low cost to performance ratio. Also considered dyes cause no environment threat, easily extractable, abundant and safe. Several methods to improve the performance of these innate dyes have been explored. Parameters viz. pH level of extract, extraction method, extracting temperature, multilayer configurations and usage with nanostructures can be considered as a great step to reach the higher value of output. Among natural dyes root of maharanga bi color herb, mangosteen pericarp etc. have proved their candidature as best anchoring choromophores in dyesensitized solar cells.
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The source of the optical properties of natural melanin persists as an impressive conundrum, hindering a thorough comprehension of the complicated photo-protective contribution of these extensive natural pigments and the pragmatic design of revolutionary bioinspired materials for optoelectronic functionalities. Melanin is a natural pigment distributed in vivo, and provides protection from the sun rays, exhibiting a strong wide-band UVvisible absorption. In the present study, we investigated the optical properties of natural melanin at different pH concentrations within the framework of experimental techniques, namely, UV-visible absorption, Fourier transform infrared spectroscopy (FTIR), and fluorescence spectroscopies. The results indicate that the optical absorption and fluorescence of natural melanin are enhanced within the near-UV and visible regimes with an increase in the solution concentration, are dependent on the pH level, and can impact the emergence of a broad band of visible absorption. The variations in the optical absorption spectra of natural melanin solutions at various pH levels will demonstrate novel rational strategies for controlling their optical properties for potential optoelectronic applications.
Natural Dyes for Solar Cell Application: Uv-Visible Spectra and Outdoor Photovoltaic Performance
Research Journal of Applied Sciences, Engineering and Technology
Successful conversion of visible light into electrical output was achieved by using four locally available natural dyes as wide band gap semiconductor sensitizers in dye-sensitized solar cells. Natural dyes extracted from Java plum (Syzigium cumin), Red cabbage (Brassica oleracea), Hibiscus rosa-sinensis flower, and Begonia rex leaves were employed as light-absorbing dyes anchored to nanostructured mesoporous TiO2 film photo anode. Simple procedures were employed in extracting natural dyes. The dye extracts were stored for four months prior to UV-vis spectra and photoelectrical measurements. The absorption spectra analyses for all extracts carried out in the wavelength range 350 to 800 nm, showed a wide and significant absorption spectrum in UV and visible regions. Photovoltaic parameters such as short-circuit current (Jsc), open-circuit voltage (Voc), fill factor (FF), power output (Pm), and energy conversion efficiency (η) were determined for the four dyes. The Conversion efficien...
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ACS Omega, 2019
The development of technologies integrating solar energy conversion and energy storage functions is critical for limiting the anthropogenic effects on climate change and preventing possible energy shortages related to the increase of the world population. In our work, we explored the possibility to integrate the conversion and storage functions within the same multifunctional biosourced material. We identified the redoxactive, quinone-based, melanin pigment, featuring a broadband absorption in the UV−vis region, as the ideal candidate for such an exploration. Electrodes of melanin on carbon paper were investigated for their morphological, optical, and voltammetric characteristics prior to being assembled into symmetric supercapacitors operating in aqueous electrolytes. We observed that, under solar light, the capacity and capacitance of melanin electrodes significantly increase with respect to the dark conditions (by 22 and 39%, respectively). Once in a supercapacitor configuration, besides featuring a Coulombic efficiency close to 100% after 5000 cycles, the capacitance and capacity of the electrodes, rated by the initial values, improve after prolonged illumination, as it is the case for the energy and power density.
Study of Natural Dyes for Sensitized Solar Cells Applications
We have synthesized and used several natural dyes such as extracted from: Spinach, Beet, Henna, Strawberry, Red cabbage, and Mloukhia. The absorption of the extracted dyes diluted in ethanol or distilled water were measured using UV–Vis spectrophotometer. We have studied the topology of these films by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) patterns of synthesized TiO2. The contents of Ti and O of synthesized TiO are 30 % and 50 % corresponding to closely Ti4+ state. The absorption of the TiO2 thin films immersed in these dyes was also measured in order to tune the change. The absorption in Beet and Red cabbage is more significant compared to other natural dyes.
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Journal of Non-Crystalline Solids, 2009
Natural and synthetic melanin have been investigated by means of optical, electrical and photoelectronic measurements. Optical measurements evidence absorption curves which allow to estimate optical gap for synthetic melanin, by using Tauc's method. Dark conductivity and photoconductivity measurements were performed as a function of temperature and for different duration of thermal treatments. It has been evidenced that both quantities are thermally activated and thermal treatments play a very important role as far as gap states are concerned.
Natural Pigment-Based Dye-Sensitized Solar Cells
The performance of dye-sensitized solar cells (DSSC) based on natural dyes extracted from five different sources is reported. These are inexpensive, have no nutritional use, and are easy to find in Mexico. The solar cells were assembled using a thin film and a TiO2 mesoporous film on ITO-coated glass; these films were characterized by FTIR. The extracts were characterized using UV-Vis and typical I-V curves were obtained for the cells. The best performance was for Punica Granatum with a solar energy conversion efficiency of 1.86%, with a current density Jsc of 3.341 mA/cm 2 using an incident irradiation of 100 mW/cm 2 at 25 ºC.