Optical studies on some dyes for liquid solar concentrators
TL;DR: In this paper, the spectral properties of some luminescent dyes, derivatives of xanthene and benzoxazinone groups, in a liquid polymer matrix, Triton x-100, have been studied.
About: This article is published in Solar Energy Materials.The article was published on 1990-03-01. It has received 17 citations till now. The article focuses on the topics: Matrix (mathematics) & Xanthene.
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TL;DR: The luminescent solar concentrator (LSC) concept appeared almost forty years ago, as a solution to overcome the limitations related to photovoltaic cell efficiency as mentioned in this paper.
Abstract: The luminescent solar concentrator (LSC) concept appeared almost forty years ago, as a solution to overcome the limitations related to photovoltaic cell efficiency. Nowadays, they are seen as a promising approach to integrate photovoltaic elements into the built environment, in an invisible way and without detrimental effects to the aesthetics of the building or the quality of life of the inhabitants. LSCs are devices comprising a transparent matrix embedding optically active centers that absorb the incident radiation, which is re-emitted at a specific wavelength and transferred by total internal reflection to photovoltaic cells located at the edges of the matrix. During the last few decades, several optically active materials have been tested for LSCs in an endless quest for the most efficient device. Nowadays, one of the world's major concerns is the environmental impact of our choices. Thus, the present and future path for LSCs must include the search for nature-friendly materials, with little environmental impact, and, in this sense, this Perspective offers a general overview of the potential of environmentally-friendly materials for LSCs.
10 citations
25 Oct 2013
7 citations
TL;DR: In this article, the optical energy gap and the band tail width were calculated for fluorescent solar concentrators using FTIR spectroscopically using different organic dyes in PMMA and the results showed that the value of the refractive index increases with dye concentration in the PMMA.
Abstract: Films for fluorescent solar concentrators applications were prepared by doping different organic dyes in PMMA. The products were characterized spectroscopically using FTIR. The optical energy gap and the band tail width were calculated. A simple but effective method is used to determine the optical constants (n and k) for the films from combination of transmission and specular reflection in a wide range of wavelengths (200–2400 nm). The results of these measurements show that the value of the refractive index increases with dye concentration in the PMMA. Also, three films of Rh-6G/PMMA, perylene/PMMA, and K1/PMMA were prepared with the same optical density and the optical constants of these films were determined.
6 citations
TL;DR: In this article, the Coulomb well barrier of charge carriers (W M ) was calculated for polymethylmethacrylate (PMMA) and mixed with phthalocyanine, Ni-phthalocyanines, and Hematoporphyrin IX chloride laser dyes.
Abstract: The electrical properties: dc-electrical conductivity (σ DC ), ac-electrical conductivity (σ AC ), dielectric permittivity (e'), and dielectric loss (∈") for pure polymethylmethacrylate (PMMA) and mixed with phthalocyanine, Ni-phthalocyanine, and Hematoporphyrin IX chloride laser dyes have been investigated. The conductivity values for all polymer-dye samples are higher than that of the pure PMMA. For all investigated samples, at constant temperature, the frequency dependence of (σ AC ) was found to obey the relation (σ AC ) = Aω s . The results are discussed according to the correlated barrier hopping CBH mechanism, from which the Coulomb well barrier of charge carriers (W M ) was calculated. For the dye-doped samples, phthalocyanine mixed sample showed the larger value of (W M ) compared with the others. At all frequencies, ∈' values for doped samples were higher than that of pure one. This is due to a free volume enhancement offered by the large size of the dye molecule. Also, the addition of dyes to PMMA causes an increase in the intensity of the loss peak (e") accompanied by a shift in its position. The effect of chemical structure of investigated dyes on the electrical properties are discussed.
6 citations
29 Sep 2008
TL;DR: An overview of the general properties of organized assembly (ordered media) systems such as aqueous surfactant and bile salt micelles, lipid and surfactants vesicles (liposomes) and cyclodextrins (CDs) is provided in this paper.
Abstract: This article provides an overview of the general properties of organized assembly (ordered media) systems such as aqueous surfactant and bile salt micelles, lipid and surfactant vesicles (liposomes) and cyclodextrins (CDs) and summarizes their utilization to enhance the performance of analytical fluorescence measurements. In many instances, organic molecules and metal complex species, when included within a CD cavity or solubilized and bound to surfactant aggregates, exhibit enhanced fluorescence. This gives rise to improved detectability of such analytes. The altered microenvironment within the organized medium is capable of impeding the interfering action of other species (inorganic or organic) present in the sample matrix. This often can improve the selectivity of the analytical method. These benefits of improved sensitivity and selectivity arise from the compartmentalization, isolation and shielding of the excited singlet state of the guest analyte from quenching and nonradiative decay processes as well as prevent side reactions that otherwise can occur in bulk solution (or sample matrix). In addition, organic solvents or time-consuming extraction steps can be avoided owing to the increased solubility of the nonpolar organic or inorganic reagents and/or analyte molecules in water in the presence of the organized medium; allowing for the use of an aqueous medium to perform the procedure. The possibility of conducting reactions and forming fluorescent organic or metal chelates in micellar (or other organized) media that are not observed in a bulk homogeneous solvent system serves to expand the scope of chemistries that one can consider using to design/develop new, unique and improved fluorescent assays. Numerous representative examples of fluorescent methods for determination of both organic and inorganic analytes are provided which serve to illustrate the advantages and benefits accrued from the use of the micelles, vesicles, liposomes or CDs in such procedures. Some experimental considerations and cautions to keep in mind when utilizing organized media are also delineated. An extensive reference section is provided so that the interested reader can easily refer to such for more detailed information on these systems and topics.
5 citations
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01 Jan 1973TL;DR: CRC handbook of chemistry and physics, CRC Handbook of Chemistry and Physics, CRC handbook as discussed by the authors, CRC Handbook for Chemistry and Physiology, CRC Handbook for Physics,
Abstract: CRC handbook of chemistry and physics , CRC handbook of chemistry and physics , کتابخانه مرکزی دانشگاه علوم پزشکی تهران
52,268 citations
4,512 citations
700 citations
TL;DR: In this article, a new principle for solar energy conversion is proposed and evaluated theoretically, and the optical path length in a triangular collector is computed, which offers the advantage of separating the various fractions of light and converting them with solar cells with different bandgaps.
Abstract: A new principle for solar energy conversion is proposed and evaluated theoretically. Collection and concentration of direct and diffuse radiation is possible by the use of a stack of transparent sheets of material doped with fluorescent dyes. High efficiency of light collection can be achieved by light guiding and special design of collectors. The optical path length in a triangular collector is computed. In combination with solar cells this type of collector offers the advantage of separating the various fractions of light and converting them with solar cells with different bandgaps. Theoretical conversion efficiency under optimum conditions is 32% for a system with four semiconductors. Thermal energy conversion offers several advantages over conventional collectors: High temperature and efficiency even under weak illumination, separation of heat transport and radiation collection, low thermal mass. Thermal efficiency is computed to be between 42% and 60%. Very attractive appear hybrid systems for generation of thermal and electric energy. An estimate of the economics of electricity generation shows that due to the concentration costs can be much lower than possible today. With the use of only silicon cells the breakeven point of $0.5/W is almost reached. Practical difficulties to be solved are: Synthesis of dyes with stringent requirements, identification of plastic materials with high transparency and development of solar cells with higher bandgaps.
638 citations
TL;DR: Three independent techniques for measuring self-absorption rates are developed, time-resolved emission, steady-state polarization anisotropy, and spectral convolution, and simple relationships relating the efficiency and gain of an LSC to key spectroscopic parameters of its constituents are given.
Abstract: Experimental techniques are developed to determine the applicability of a particular luminescing center for use in a luminescent solar concentrator (LSC). The relevant steady-state characteristics of eighteen common organic laser dyes are given. The relative spectral homogeneity of such dyes are shown to depend upon the surrounding material using narrowband laser excitation. We developed three independent techniques for measuring self-absorption rates; these are time-resolved emission, steady-state polarization anisotropy, and spectral convolution. Preliminary dye degradation and prototype efficiency measurements are included. Finally, we give simple relationships relating the efficiency and gain of an LSC to key spectroscopic parameters of its constituents.
264 citations