About Supramolecular Assemblies of π-Conjugated Systems

4. Survey of Novel Multiphoton Active Materials 1257 4.1. Multiphoton Absorbing Systems 1257 4.2. Organic Molecules 1257 4.3. Organic Liquids and Liquid Crystals 1259 4.4. Conjugated Polymers 1259 4.4.1. Polydiacetylenes 1261 4.4.2. Polyphenylenevinylenes (PPVs) 1261 4.4.3. Polythiophenes 1263 4.4.4. Other Conjugated Polymers 1265 4.4.5. Dendrimers 1265 4.4.6. Hyperbranched Polymers 1267 4.5. Fullerenes 1267 4.6. Coordination and Organometallic Compounds 1271 4.6.1. Metal Dithiolenes 1271 4.6.2. Pyridine-Based Multidentate Ligands 1272 4.6.3. Other Transition-Metal Complexes 1273 4.6.4. Lanthanide Complexes 1275 4.6.5. Ferrocene Derivatives 1275 4.6.6. Alkynylruthenium Complexes 1279 4.6.7. Platinum Acetylides 1279 4.7. Porphyrins and Metallophophyrins 1279 4.8. Nanoparticles 1281 4.9. Biomolecules and Derivatives 1282 5. Nonlinear Optical Characterizations of Multiphoton Active Materials 1282

Multiphoton Absorbing Materials : Molecular Designs, Characterizations, and Applications

Room-temperature phosphorescent materials that emit light in the visible (red, green, and blue; from 400 to 700 nm) have been a major focus of research and development during the past decades, due to their applications in organic light-emitting diodes (OLEDs), light-emitting electrochemical cells, photovoltaic cells, chemical sensors, and bio-imaging. In recent years, near-infrared (NIR) phosphorescence beyond the visible region (700–2500 nm) has emerged as a new, promising, and challenging research field with potential applications toward NIR OLEDs, telecommunications, night vision-readable displays. Moreover, NIR phosphorescence holds promise for in vivo imaging, because cells and tissues exhibit little absorption and auto-fluorescence in this spectral region. This review describes the overall progress made in the past ten years on NIR phosphorescent transition-metal complexes including Cu(I), Cu(II), Cr(III), Re(I), Re(III), Ru(II), Os(II), Ir(III), Pt(II), Pd(II), Au(I), and Au(III) complexes, with a primary focus on material design complemented with a selection of optical, electronic, sensory, and biologic applications. A critical comparison of various NIR phosphorescent materials reported in the literature and a blueprint for future development in this field are also provided.

Near-infrared phosphorescence: materials and applications

A large basis set of α-oligothiophenes with two to seven rings (α2−α7), also including thiophene, α1, have been investigated in five solvents regarding absorption, fluorescence and phosphorescence, quantum yields of fluorescence (φF) and triplet formation (φT), lifetimes of fluorescence and the triplet state, quantum yields of singlet oxygen production (φΔ), all rate constants kF, kIC, kISC, and several of the foregoing as a function of temperature. Ten different theoretical calculations across several levels including three levels of ab initio have been carried out regarding which conformer is lowest in energy and the ΔH's among all conformers of α2, α3 and α5, as well as calculations of transitions energies of the α-oligothiophenes. We have shown that the (l) 1Bu state is the lowest singlet state for all α2−α7 in any solvent, in contradiction to previous predictions for the higher members. Based on absorption and fluorescence data and calculations of atomic charges in S0 and S1, the ground state is twis...

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Comprehensive Evaluation of the Absorption, Photophysical, Energy Transfer, Structural, and Theoretical Properties of α-Oligothiophenes with One to Seven Rings

Organic photovoltaic materials and devices

Picosecond photoinduced dichroism in solutions of thiophene oligomers

α‐Sexithiopene; A new photochromic material for a prototype ultrafast incoherent‐to‐coherent optical converter

We report on a method aimed at measuring both the real and imaginary parts of the third-order Kerr-type nonlinear-optical susceptibility of isotropic materials. It is based on Kerr ellipsometry in which analysis of the polarization state of transmitted light between a nearly crossed polarizer and an analyzer allows separation of pump-induced dichroism and birefringence. The method provides a natural measurement of nonlinear phase retardations in angle units, without any calibration procedure. By using a white-light continuum as a probe, this property is used to get a simultaneous measurement of the nonlinear dispersion in the whole visible spectrum. It is illustrated in tetramethylsilane, where stimulated Stokes and anti-Stokes Raman contributions to the nonlinearity are observed.

Phase and frequency resolution of picosecond optical Kerr nonlinearities

Determination of the two-photon absorption spectrum of a soluble polythiophene

Charge-transfer complexes formed by a discogenic electron donor (2,3,6,7,10,11-hexa-n-pentyloxytriphenylene) and a non-discogenic electron acceptor (2,4,7-trinitrofluoren-9-one) in non-polar solvents are studied by picosecond time-resolved absorption spectroscopy based on Kerr ellipsometry. The transient spectra obtained following laser excitation either in the charge-transfer band or in the lower lying local acceptor band correspond to the oxidized donor and reduced acceptor. Recombination of the geminate ion pair occurs with a first order rate constant of 1.7 × 1010 s–1. It is shown that the polarization of the transient species absorption is orthogonal to the charge-transfer transition. It is also demonstrated that the relative orientation between the donor and the acceptor in the geminate ion pair is not random.

Nicola Pfeffer

Papers

Picosecond photoinduced dichroism in solutions of thiophene oligomers

α‐Sexithiopene; A new photochromic material for a prototype ultrafast incoherent‐to‐coherent optical converter

Phase and frequency resolution of picosecond optical Kerr nonlinearities

Determination of the two-photon absorption spectrum of a soluble polythiophene

Charge-transfer complexes of discogenic molecules : a time-resolved study based on kerr ellipsometry