In-line solar spectrum alteration

In-line Solar Spectrum Alteration with Nanotechnology... 

Many issues must be adequately addressed for successful inqilementation of in-line solar spectrum alteration using organic dyes. Many of these issues for inline spectrum alteration are shared widi the luminescent solar concentrator. Therefore, the wealth of literature that exists for the luminescent solar concentrator is a very useful information source. Among these issues are dye stability, re-absorpdon, isotropic emission, quantum yield, and matrix absorption. In the following paragrtq)hs, each of these issues will be discussed. 

The development of emission spectroscopy was a long process initiated by Descartes in 1637 with his illustration that white light can be decomposed into its components with a prism. Several scientists later observed dark lines in the solar spectrum (e.g., Wollaston in 1802). Their constancy was noted and they were mapped in detail by Fraunhofer in 1814. He also noted the appearance of colored, changing lines from other sources. Talbot in 1826 correlated the appearance of some lines with the presence of certain elements. Similar observations were described later by other scientists without arousing much interest at the time. In this context the work of Alter is significant, he produced the first spectral atlas, a tabulation relating spectral lines to chemical elements, in 1854. 

These spectrumraltering dyes would be applied in a non-absorbing matrix to the solar incident side of existii photovoltaics. The result would be tiut the spectral distribution of photons inci nt on tiie photovoltaic device would differ from that of the incoming solar spectrum. Thus, the dye would alter the solar spectrum in-line (see Figure 1) with no area concentration of energy. 

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... 

Figure /. Schematics of the in-line spectrum alteration concept and the luminescent solar concentrator.

Another issue regarding the use of spectrum shifting dyes is re-absorption of emitted photons before they enter the photovoltaic device (5,13,14). This occurs due to an overlap in the absorption and emission bands of a dye. While this is an enormous problem for luminescent solar concentrators, it should not be as significant for the in-line spectrum alteration concept. This is because tiie optical... 

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