Optical studies on some dyes for liquid solar concentrators

Thirty Years of Luminescent Solar Concentrator Research: Solar Energy for the Built Environment

Abstract: Research on the luminescent solar concentrator (LSC) over the past thirty-odd years is reviewed. The LSC is a simple device at its heart, employing a polymeric or glass waveguide and luminescent molecules to generate electricity from sunlight when attached to a photovoltaic cell. The LSC has the potential to find extended use in an area traditionally difficult for effective use of regular photovoltaic panels: the built environment. The LSC is a device very flexible in its design, with a variety of possible shapes and colors. The primary challenge faced by the devices is increasing their photon-to-electron conversion efficiencies. A number of laboratories are working to improve the efficiency and lifetime of the LSC device, with the ultimate goal of commercializing the devices within a few years. The topics covered here relate to the efforts for reducing losses in these devices. These include studies of novel luminophores, including organic fluorescent dyes, inorganic phosphors, and quantum dots. Ways to limit the surface and internal losses are also discussed, including using organic and inorganic-based selective mirrors which allow sunlight in but reflect luminophore-emitted light, plasmonic structures to enhance emissions, novel photovoltaics, alignment of the luminophores to manipulate the path of the emitted light, and patterning of the dye layer to improve emission efficiency. Finally, some possible ‘glimpses of the future’ are offered, with additional research paths that could result in a device that makes solar energy a ubiquitous part of the urban setting, finding use as sound barriers, bus-stop roofs, awnings, windows, paving, or siding tiles.

Enhancing the performance of building integrated photovoltaics

Abstract: Recent research in Building Integrated Photovoltaics (BIPV) is reviewed with the emphases on a range of key systems whose improvement would be likely to lead to improved solar energy conversion efficiency and/or economic viability. These include invertors, concentrators and thermal management systems. Advances in techniques for specific aspects of systems design, installation and operation are also discussed.

Supramolecular Luminescent Sensors

Abstract: There is great need for stand-alone luminescence-based chemosensors that exemplify selectivity, sensitivity, and applicability and that overcome the challenges that arise from complex, real-world media. Discussed herein are recent developments toward these goals in the field of supramolecular luminescent chemosensors, including macrocycles, polymers, and nanomaterials. Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry as well as analytes of interest and common luminophores. State-of-the-art developments in the fields of polymer and nanomaterial sensors are also examined, and some remaining unsolved challenges in the area of chemosensors are discussed.

Quantum dot solar concentrators: Electrical conversion efficiencies and comparative concentrating factors of fabricated devices

Abstract: A novel, non-tracking concentrator is described, which uses nano-scale quantum dot technology to render the concept of a fluorescent dye solar concentrator (FSC) a practical proposition. The quantum dot solar concentrator (QDSC) comprises quantum dots (QDs) seeded in materials such as plastics and glasses that are suitable for incorporation into building facades. Photovoltaic (PV) cells attached to the edges convert direct and diffuse solar energy collected into electricity for use in the building. Small scale QDSC devices were fabricated. Devices have been characterised to determine current, voltage and power readings. Electrical conversion efficiencies, fill factors and comparative concentrating factors are reported.

Electrical conduction and dielectric properties of poly(methyl methacrylate)/perylene solar concentrators

Abstract: Poly(methyl methacrylate) doped with fluo- rescent perylene dye was prepared by both radical polymer- ization of methyl methacrylate and solvent casting from polymer solutions. The samples were characterized by dif- ferential scanning calorimetry, Fourier transform infrared spectroscopy, electrical conductivity, and dielectric proper- ties. Both conductivity and dielectric properties were mea- sured in the temperature range 303- 433 K and the frequency range 10 3 to 5 10 6 Hz. The results show that the direct- current electrical conductivity increased by increasing dye content in solvent-cast samples, whereas it decreased radi- cally polymerized samples. The results of alternating-cur- rent conductivity suggest electron hopping between filled and empty localized states. The study of dielectric properties showed two relaxation peaks corresponding to the dipole segmental and dipole group losses. Explanations based on the polymer free volume and acid- base interactions were proposed to examine the influence of the sample prepara- tion and perylene dye concentration on the glass-transition temperature and dielectric relaxation of the samples. The obtained results recommend the thermal and molecular sta- bility of luminescent solar concentrator (LSC) matrices pre- pared by radical polymerization over those prepared by solvent casting. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 793- 805, 2003

CRC Handbook of Chemistry and Physics

Abstract: CRC handbook of chemistry and physics , CRC handbook of chemistry and physics , کتابخانه مرکزی دانشگاه علوم پزشکی تهران

Solar Energy Conversion with Fluorescent Collectors

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.

Luminescent solar concentrators. 2: Experimental and theoretical analysis of their possible efficiencies.

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.