Luminescent organic dyes

Most LSC devices employ a luminescent organic dye dispersed in a planar plastic sheet to collect incident sunlight and concentrate the emitted light at the edges. Many organic dyes are known to function in such devices and it has now been reported that trans-thioindigo is the most efficient dye tested to date. Thus, the efficiency of an attached Si solar... 

In Chap. 2, novel thermostable luminophores comprised of Eu(ni) coordination polymers [Eu(hfa)3(dpb)] , [Eu(hfa)3(dpbp)] , and [Eu(hfa)3(dppcz)] were successfully synthesized. In particular, [Eu(hfa)3(dppcz)] exhibited both high emission quantum yields (< Ln = 83 %) and remarkable thermal stability (decomposition point = 300 °C) due to a tight-binding stmcture composed of Eu(III) ions and low-vibrational phosphine oxide, although many types of luminescent organic dyes are generally decomposed at temperatures under 200 °C. The emission quantum yields of these coordination polymers are similar to those of strong-luminescent coordination polymers in former chapters. These coordination polymers are expected to employ in optics applications such as luminescent plastics, displays, and opto-electronic devices. 

Rubinov AN, Tomin VI (1970) Bathochromic luminescence in solutions of organic dyes at low temperatures. Opt Spectros 29 578-580... 

Rubinov AN, Tomin VI (1971) Bathochromic luminescence of organic dyes in alcohol solutions and polymer matrices. Opt Spectros 32 424-428... 

Optical fibres composed of plastics are also transparent in the visible spectral region but optical losses reach 102 - 103 dB/km13. Their refractive index varies from 1.35 to 1.6 depending on the kind of polymer used (e.g. polymethymethacrylate PMMA -1.49). The chemical resistance is much worse than that of silica fibres and thermal stability is incomparable. On the other hand, low temperature processes of plastic fibre preparation allow us mix the starting polymer with organic dyes which enables the production of luminescent fibres suitable e.g. for fluorescence-based sensing13. 

The fluorescence decay kinetics of exemplary chosen QDs and small organic dyes are compared in Fig. 2. The size of the fluorescence parameter luminescence lifetime is determined by the electronic nature of the transitions involved. As a rule... 

Fig. 2 Comparison of the luminescence decays of QDs and organic dyes. InP and CdTe QDs decay multiexponentially with a mean lifetime (ii/e) of 17 and 6 ns, respectively. The organic dye Cy5 shows monoexponential decay with tf of 1.5 ns...

Clapp AR, Medintz IL, Fisher BR, Anderson GP, Mattoussi FI (2005) Can luminescent quantum dots be efficient energy acceptors with organic dye donors J Am Chem Soc 127 1242-1250... 

The disadvantages of organic dyes (low photostability, insufficient brightness, short lifetimes, etc.) have resulted in competition from luminescent metal-ligand complexes, semiconductor nanoparticles (Quantum Dots), and conjugated polymers. These new materials show advanced performance in a variety of applications... 

Abstract Silver clusters, composed of only a few silver atoms, have remarkable optical properties based on electronic transitions between quantized energy levels. They have large absorption coefficients and fluorescence quantum yields, in common with conventional fluorescent markers. But importantly, silver clusters have an attractive set of features, including subnanometer size, nontoxicity and photostability, which makes them competitive as fluorescent markers compared with organic dye molecules and semiconductor quantum dots. In this chapter, we review the synthesis and properties of fluorescent silver clusters, and their application as bio-labels and molecular sensors. Silver clusters may have a bright future as luminescent probes for labeling and sensing applications. 

From our research group Santra et al. [11,41,42] reported the development of novel luminescent nanoparticles composed of inorganic luminescent dye RuBpy, doped inside a sihca network. These dye-doped silica nanoparticles were synthesized using a w/o microemulsion of Tx-lOO/cyclohexane/ n-hexanol/water in which controlled hydrolysis of the TEOS leads to the formation of mono dispersed nanoparticles ranging from 5-400 nm. This research illustrates the efficiency of the microemulsion technique for the synthesis of uniform nanoparticles. These nanoparticles are suitable for biomarker application since they are much smaller than the cellular dimension and they are highly photostable in comparison to most commonly used organic dyes. It was shown that maximum liuninescence intensity was achieved when the dye content was around 20%. Moreover, for demonstration... 

Fig. 3 Luminescence lifetimes r and excitation wavelength Xex of typical organic dyes and metal chelates...

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