Fluorescence methods are being used increasingly in biochemical, medical, and chemical research. This is because of the inherent sensitivity of this technique. and the favorable time scale of the phenomenon of fluorescence. 8 Fluorescence emission occurs about 10- sec (10 nsec) after light absorp tion. During this period of time a wide range of molecular processes can occur, and these can effect the spectral characteristics of the fluorescent compound. This combination of sensitivity and a favorable time scale allows fluorescence methods to be generally useful for studies of proteins and membranes and their interactions with other macromolecules. This book describes the fundamental aspects of fluorescence. and the biochemical applications of this methodology. Each chapter starts with the -theoreticalbasis of each phenomenon of fluorescence, followed by examples which illustrate the use of the phenomenon in the study of biochemical problems. The book contains numerous figures. It is felt that such graphical presentations contribute to pleasurable reading and increased understand ing. Separate chapters are devoted to fluorescence polarization, lifetimes, quenching, energy transfer, solvent effects, and excited state reactions. To enhance the usefulness of this work as a textbook, problems are included which illustrate the concepts described in each chapter. Furthermore, a separate chapter is devoted to the instrumentation used in fluorescence spectroscopy. This chapter will be especially valuable for those perform ing or contemplating fluorescence measurements. Such measurements are easily compromised by failure to consider a number of simple principles."

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Principles of fluorescence spectroscopy

A polymer solar-cell based on a bulk hetereojunction design with an internal quantum efficiency of over 90% across the visible spectrum (425 nm to 575 nm) is reported. The device exhibits a power-conversion efficiency of 6% under standard air-mass 1.5 global illumination tests.

Bulk heterojunction solar cells with internal quantum efficiency approaching 100

-phenylenevinylene)s L4. Fluorene-Based Conjugated Polymers L4.1. Fluorene-Based Copolymers ContainingElectron-Rich MoietiesM4.2. Fluorene-Based Copolymers ContainingElectron-Deﬁcient MoietiesN4.3. Fluorene-Based Copolymers ContainingPhosphorescent ComplexesQ5. Carbazole-Based Conjugated Polymers R5.1. Poly(2,7-carbazole)-Based Polymers R5.2. Indolo[3,2-

https://ir.nctu.edu.tw:443/bitstream/11536/6508/1/000271856900020.pdf

Synthesis of Conjugated Polymers for Organic Solar Cell Applications

Aggregation-induced emission: phenomenon, mechanism and applications.

Solution-processed bulk-heterojunction solar cells have gained serious attention during the last few years and are becoming established as one of the future photovoltaic technologies for low-cost power production. This article reviews the highlights of the last few years, and summarizes today's state-of-the-art performance. An outlook is given on relevant future materials and technologies that have the potential to guide this young photovoltaic technology towards the magic 10% regime. A cost model supplements the technical discussions, with practical aspects any photovoltaic technology needs to fulfil, and answers to the question as to whether low module costs can compensate lower lifetimes and performances.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adma.200801283

Polymer‐Fullerene Bulk‐Heterojunction Solar Cells

On the basis of theoretical models and calculations, several alternating polymeric structures have been investigated to develop optimized poly(2,7-carbazole) derivatives for solar cell applications. Selected low band gap alternating copolymers have been obtained via a Suzuki coupling reaction. A good correlation between DFT theoretical calculations performed on model compounds and the experimental HOMO, LUMO, and band gap energies of the corresponding polymers has been obtained. This study reveals that the alternating copolymer HOMO energy level is mainly fixed by the carbazole moiety, whereas the LUMO energy level is mainly related to the nature of the electron-withdrawing comonomer. However, solar cell performances are not solely driven by the energy levels of the materials. Clearly, the molecular weight and the overall organization of the polymers are other important key parameters to consider when developing new polymers for solar cells. Preliminary measurements have revealed hole mobilities of about ...

Toward a rational design of poly(2,7-carbazole) derivatives for solar cells.

Steady state and time-resolved fluorescence spectroscopy were employed to study the fluorescence from non-metastatic, metastatic and non-tumorigenic cell lines from different species. Excitations at 310 nm and 350 nm were used to monitor tryptophan and reduced nicotinamide adenine dinucleotide (NADH) fluorescence respectively. Subtle and consistent differences were observed between different categories of cell lines. It was found that the tryptophan to NADH fluorescence intensity ratio is higher in metastatic cell lines than in non-metastatic and normal cell lines. The fluorescence decay of the tryptophan residue in different cell lines was best described by triple exponential kinetics, whereas the NADH fluorescence decay was best described by mainly double and, in some cases, triple exponential kinetics. The average fluorescence lifetimes for tryptophan were in the range 2.5-3.7 ns. The average lifetime of NADH was lower (by a factor of approximately three) in metastatic cells than in non-metastatic cells and this finding is consistent for cell lines from different origins (rat or human). Correcting the fluorescence intensity for the average fluorescence lifetime of each species and for the volume of each cell line, it was shown that the concentrations of tryptophan and NADH are consistently higher in malignant metastatic cancer cells than in non-metastatic cells.

Steady state and time-resolved fluorescence properties of metastatic and non-metastatic malignant cells from different species

The ground and excited states of covalently linked fluorene-based dimers were investigated by theoretical methods and by UV−vis and fluorescence spectroscopies. The optimized structures and the cha...

Theoretical and Experimental Investigations of the Spectroscopic and Photophysical Properties of Fluorene-Phenylene and Fluorene-Thiophene Derivatives: Precursors of Light-Emitting Polymers

Interactions between 3H-indole derivatives, their cations and anions, and microheterogeneous environments like micelles and vesicles have been studied extensively in our laboratory recently. We report herein the interactions of 2-(p-aminophenyl)-3,3-dimethyl-5-cyano-3H-indole (1) and 2-[p-(dimethylamino)phenyl]-3,3-dimethyl-5-cyano-3H-indole (2) with aqueous solutions of β-cyclodextrin (β-CD), studied by absorption and fluorescence steady-state and time-resolved measurements. The stoichiometries of the cyclodextrin:guest inclusion complexes have been determined by steady-state fluorescence measurements. The data reveal that two types of complexes, i.e., 1:1 and 2:1 types are formed. Thermodynamic parameters are calculated at six different temperatures. Spectral characteristics, bandwidths, and photophysical parameters indicate that molecule 2 is better protected against hydrophilic interactions. Protonation reactions carried out at different concentrations of β-CD show that the protonation is inhibited at...

Spectral and Photophysical Studies of Inclusion Complexes of Some Neutral 3H-Indoles and Their Cations and Anions with β-Cyclodextrin

Fluorescence lifetimes (τ F ) of 2-[p-(dimethylamino)phenyl]-3,3-dimethyl-3H-indole (1) have been extensively studied in a two-component mixture of p-dioxane/water and also in a three-component mixture of n-heptane/AOT (sodium bis(2-ethylhexyl) sulfosuccinate)/water We have applied the concept of «dielectric enrichment» to solute/mixed solvents systems in order to evaluate the effective dielectric constants at the AOT interfaces in n-heptane We have shown that the effective dielectric constant (D) at the interface increases from 23 (water molar ratio W=O) to approximately 90 before reaching a plateau at Wœ512

Gilles Durocher

Papers

Toward a rational design of poly(2,7-carbazole) derivatives for solar cells.

Steady state and time-resolved fluorescence properties of metastatic and non-metastatic malignant cells from different species

Theoretical and Experimental Investigations of the Spectroscopic and Photophysical Properties of Fluorene-Phenylene and Fluorene-Thiophene Derivatives: Precursors of Light-Emitting Polymers

Spectral and Photophysical Studies of Inclusion Complexes of Some Neutral 3H-Indoles and Their Cations and Anions with β-Cyclodextrin

Polarity of AOT micellar interfaces : use of the preferential solvation concepts in the evaluation of the effective dielectric constants