Search results for "Organic Dye"

Influence of spatial arrangements of π-spacer and acceptor of phenothiazine based dyes on the performance of dye-sensitized solar cells

2013

Abstract Three phenothiazine based organic dyes PTA , PDTA and PTDA with D– π –A, π –D– π –A and A– π –D– π –A frameworks were designed and synthesized for the dye sensitized solar cells (DSSCs). Phenothiazine with octyloxyphenyl moiety acts as donor while thiophene and cyanoacetic acid units act as a π -spacer and an acceptor, respectively. The effects of the molecular structures of the dyes on the performance of the DSSCs were investigated systematically along with their photophysical and photoelectrochemical properties. The dye PTDA with A– π –D– π –A framework exhibited a better light harvesting capacity and an effective electron extraction pathway from the electron donor to the TiO 2 s…

Organic Dye Bearing Asymmetric Double Donor-π-Acceptor Chains for Dye-Sensitized Solar Cells

2011

A novel efficient metal free sensitizer containing asymmetric double donor-π-acceptor chains (DC) was synthesized for dye-sensitized solar cells (DSSCs). Comparing to 3.80%, 4.40% and 4.64% for the DSSCs based on the dyes with single chain (SC1, SC2) and cosensitizers (SC1 + SC2), the overall conversion efficiency reaches 6.06% for DC-sensitized solar cells as a result of its longer electron lifetime and higher incident monochromatic photon-to-current conversion efficiency.

HYBRID WHITE LIGHT-EMITTING DIODES: STUDY AND FABRICATION OF THIN-FILM AND NANOWIRE-BASED DEVICES

I diodi ad emissione luminosa sono dei dispositivi a semiconduttore che posseggono straordinarie proprietà fisiche di generazione della luce. Il primo LED bianco si è mosso silenziosamente dalla metà degli anni 90 fino a un punto in cui, oggi, il mercato dell’illuminazione è stato totalmente rivoluzionato. A fronte dell’industria dell’illuminazione a stato solido che richiede LED sempre più luminosi ed economici, la ricerca scientifica risponde con strutture innovative, nuovi materiali più efficienti, anche combinati con l’uso delle nanotecnologie applicate. I diodi bianchi ibridi ad emissione luminosa, ad esempio, fanno anch’essi uso di un LED blu, come in un tradizionale diodo bianco, ma …

Impact of local compressive stress on the optical transitions of single organic dye molecules

2012

The ability to mechanically control the optical properties of individual molecules is a grand challenge in nanoscience and could enable the manipulation of chemical reactivity at the single-molecule level. In the past, light has been used to alter the emission wavelength of individual molecules or modulate the energy transfer quantum yield between them. Furthermore, tensile stress has been applied to study the force dependence of protein folding/unfolding and of the chemistry and photochemistry of single molecules, although in these mechanical experiments the strength of the weakest bond limits the amount of applicable force. Here, we show that compressive stress modifies the photophysical …

Phenothiazine: the seven lives of pharmacology's first lead structure.

2011

Rooted in the early days of organic dye chemistry, the phenothiazine structure and its derivatives have since held a prominent place in pharmacology and biomedicine. Initially used for histochemical stains of plasmodia by Paul Ehrlich, anthelmintic and antibiotic properties of phenothiazines were globally exploited in the 1930s and 1940s. Clinical use of N-substituted phenothiazines as antihistaminics (1940s), sedatives and antipsychotics (1950s) followed and continues to this day. Recently, interest in these structures has re-emerged for a variety of fascinating features in relation to neurodegenerative disease, spearheaded by the unique redox chemistry of phenothiazine--arguably the most …

ChemInform Abstract: A Highly Active System for the Metal-Free Aerobic Photocyanation of Tertiary Amines with Visible Light: Application to the Synth…

2016

A highly efficient metal-free catalytic system for the aerobic photocyanation of tertiary amines with visible light is reported. The use of air as terminal oxidant offers an improved safety profile compared with pure oxygen, the used compact fluorescent lamp (CFL) light sources are highly economical, and no halogenated solvents are required. This system not only proves to be effective for a wide variety of trialkylamines, pharmaceuticals, and alkaloids but remarkably also allows the lowest catalyst loading (0.00001 mol% or 0.1 ppm) ever reported for an organic dye. Bruylants reactions and C-alkylation/decyanations were performed on the obtained α-aminonitriles to demonstrate the postfunctio…

Picosecond absorption spectroscopy: Methods and applications in photophysical and photochemical systems

1985

Warm white LEDs based on Lumogen® Red and Yellow

2013

One of the most widespread solutions for the production of white LEDs is the frequency downconversion of a part of the light, coming from a blue source, by exciting one or more materials (typically Ce:YAG) that emit at longer wavelength [1]. In this work we report ona simple and less expensive method to fabricate warmwhite-light LEDsusingthe photoluminescence of Lumogen®, a perylene-based polymer dyecommercialized by BASF,that has already beenprovedto be a good substitute for conventi onal inorganic colour conversion [2],[3]. Standard InGaN-based blue LEDs (~ 450 nm) were fabricated on a sapphire substrate by metal organic chemical vapour deposition. Both Lumogen® Yellow, and Red dyes wered…

Solubilization by polysoaps

1994

The aqueous solubilization power of several series of micellar homopolymers and copolymers (''polysoaps'') is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect to the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes.

Switchable Supramolecular Crosslinking of Cyclodextrin-Modified Hyperbranched Polyethylenimine via Anthraquinone Dyes

2011

Two anthraquinone dyes, 5,8-di-N-adamantylamino-1,4-dihydroxyanthraquinone (AQ-OH) and 1,4-di-N-adamantylaminoanthraquinone (AQ-H), are synthesized. The combination of AQ-OH and AQ-H with hyperbranched polyethylenimine (PEI) bearing covalently attached β-cyclodextrin spontaneously formed host–guest complexes with hydrodynamic diameters of about 260 nm. Even enlarged structures of the trifunctional AQ-H were observed via DLS. Repeated measurements show that their assembly and disassembly is reversible with a critical point at 26 °C and therefore switchable via temperature. Also superstructures up to 100 μm were detected via TEM, cryo-TEM-, and SEM. Hence, a smart colored network of switchabl…