Solar reflectance index

Ti02 particles in HDPE matrix aid the polymer chains in crystalhzing into more perfect and thermally stable lamella. The number of nucleation sites is dramatically increased and the crystal size decreased. The solar reflectance was related to the degree of crystallinity, the spherulite size of HDPE, refractive index, and distribution of Ti02 particles in HDPE matrix. The ratile Ti02 increased the total solar reflectance from 28.2 to 51.1%. ... 

The ciystalline polymer has higher refractive index than the amorphous polymer of the same composition. The refractive index is a dominat factor determining solar reflectivity. In a certain temperature range the refractive index changes due to a phase transition change. For example, during solid-liquid phase transition the refiactive index of paraffins changes by 0.07 to 0.10. ... 

A single layer of a micro PS film on a silicon substrate always reduces its reflectivity, because of its lower refractive index compared to bulk Si. Hence micro and meso PS films of a thickness around 100 nm have been proposed as anti-reflec-tive coatings for solar cells [Pr8, Gr9, Pol, Bi4, Scl8, StlO]. 

Current production of solar cells is dominated by crystalline silicon modules however, due to the high refractive index of silicon, more than 30 percent of incident light is reflected back, which greatly reduces the conversion effi-... 

Optical Type. The change in refractive index between liquid and vapor around an optical prism provides a variation in internally reflected light intensity. The light intensity is sensed by a solar cell, whose varying output is detected and amplified. 

A similar, but sperate, concept to the one presented here is referred to in the literature as a luminescent solar concentrator (LSC) (4,5). Like the in-line spectrum alteration concept, the LSC consists of a luminescent material in a solid matrix. However, unlike the in-line concept, the solid matrix of an LSC is designed to channel photons emitted by the luminescent material to the matrix edges. The chaimeling occurs due to Ae fact that the matrix has an index of refraction greater than the external medium (air or vacuum), which causes conq)lete internal reflection to occur for photons emitted at angles outside of the... 

Because ihe dye molecules are typically randomly oriented in Iheir host matrix, (hey will effectively emit in an isotropic manner. For die inrline spectrum alteration concept, this isotropic emission causes approximately half of the emitted energy to be directed away from the solar cell. However, since the dyes are typically placed in a matrix material widi an index of refraction greater ttoi one and the external medium will either be air or vacuum and dius have an index of refraction near one, some of the energy emitted away from the solar cell will be redirected toward the solar cell by internal reflection. 

Porous silicon consists of silicon and air. The refl"aetive index of PS can be ehanged between refractive index of silicon (nsi = 3.84) and air (n = 1) depending on porosity. Reflectance of PS can be controlled by change of porosity during eleetroehemical fabrication by change of etching conditions (Perez 2007). For a dedicated review, see handbook chapter Refractive Index of Porous Silieon. It facilitates the application of PS layers on silicon as an ARC in solar cells. 

A lowering of the effective reflectance of silicon solar cell and possibility of formation of PS layer with smooth-changing refractive index... 

If we now consider applications in which the anti-reflective surfaces are designed for visible wavelengths or for solar radiation by using the above mentioned design rules, we get the results in Table 1 for a substrate material with refractive index Hs = 1.5 ... 

Since for a single, uniform layer the reflectance is minimized at only one wavelength defined by Eq. 2, multilayer films, comprising alternating layers of high and low index (refer to Fig. 38 in Chapter 13), and graded refractive index films have been developed. The reflectance of a solar cell coated with... 

Opacity, 363, 380-382, 465, 471, 474, 475, 773. See also Phase separation Opal, 97, 266-267 Opalescence, 266, 273 Optical film absorption, 841 antireflective, 842-847, 852 ferroelectric, 846 graded refractive index, 844-847 interference, 842 laser damage resistant, 842 multilayer, 844, 846 optoelectric, 846, 847 porosity, 842 problems, 846 reflectance, 841 refractive index, 842-848 solar energy applications, 844 transmission, 841 Optically active molecules, 760 Optical waveguide, 288, 292-295, 695, 701 See also Fiber optic preform Ordered domains. See Domain, ordered Ordering, 259, 266-268, 270, 831 of liquid layers, 411-412, 422-424, 460 of particle sols, 821-823 Order of reaction silicate condensation, 146 silicate hydrolysis, 123, 154 silicon alkoxide hydrolysis, 118, 130... 

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