Dye Doping Research Articles

Luminescent properties of benzothiazole derivatives and their application in white light emission

A saturated white-light emission was obtained by dispersing three benzothiazole analogues into a solid PMMA matrix. This skillfully avoids the detrimental energy transfer between doped dyes providing a simple approach for fabrication of white-light emitting devices.

Colorful Hydrophobic Poly(Vinyl Butyral)/Cationic Dye Fibrous Membranes via a Colored Solution Electrospinning Process.

Colorful nanofibrous membranes have attracted much attention for their visual varieties and various functionalities. In this article, a colored solution electrospinning process was used to fabricate colorful hydrophobic poly(vinyl butyral) (PVB)/cationic dye nanofibrous membranes (NFMs) successfully. The color and morphology of these as-spun nanofibrous membranes have been analyzed by colorimetry, spectroscopy, and scanning electron microscopy (SEM). It is shown that the as-spun colorful PVB-based membranes exhibit excellent level-dyeing property and color stability. Furthermore, the doping of cationic dye and the increase of dye concentration can decrease the diameter of the as-spun colored fibers, which results in better level-dyeing property and higher water contact angle more than 140°. The stained PVB fibrous membranes with excellent level-dyeing property and hydrophobicity are promising in some applications such as textiles, wallpapers, and anticorrosive coating/painting.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1763-4) contains supplementary material, which is available to authorized users.

Orientational control of liquid crystal molecules via carbon nanotubes and dichroic dye in polymer dispersed liquid crystal

ABSTRACTPolymer dispersed liquid crystals (PDLCs) using nematic liquid crystal and photo-curable polymer (NOA 65) were prepared by polymerisation-induced phase separation technique, in equal ratio (1:1) of polymer and liquid crystal (LC). We demonstrate that doping of small amount (0.125%, wt./wt.) of multiwall carbon nanotubes (CNTs) and orange azo dichroic dye in PDLC generously controlled the molecular orientation, dynamics of LC in droplet and size of droplets. The effects of multiwall CNTs and dye on PDLCs were studied in terms of transition temperature, droplet morphology, transmittance characteristic, contrast ratio and response time. The results exhibited that the values of the threshold electric fields were reduced from 8 V/µm (pure PDLC) to 1.18 and 1.72 V/µm, doped with multiwall CNTs and dye, respectively. The CNTs-doped PDLC shows faster switching response as compared with pure PDLC and dye-doped PDLC. However, dye-doped PDLC shows much higher contrast among all PDLC samples. Further, the results also illustrate that the birefringence value of LC in PDLCs was changed with doping of CNTs and dye.

Concentration dependent optical properties of rhodamine B doped poly(vinyl alcohol) solutions

The optical properties, namely refractive index (RI) studies, are reported on a series of pure and doped poly(vinyl alcohol) (PVA) in solution form. The PVA solutions were synthesized with 1, 2, 3, 4, and 5 wt% of PVA in distilled water followed by doping with Rhodamine B in concentrations ranging from 0.05 wt% to 2 wt%. The absorption spectra show an observable shift in the band edge position towards higher wavelength with increase in PVA wt%. When the dopant molecules are added, the curves are drastically modified with the occurrence of new peaks arising at higher doping concentrations along with change in the bandgap. These effects are prominent for all the concentration of PVA solution. The RI does not change much for low doping wt%. but when dopant is added in higher concentrations, it increases slightly reaching a maximum of ∼1.35 at 2 wt%. It is observed that host polymer properties dominate at low doping while a combination of host polymer and dopant dye properties dominate at higher doping concentrations.

Modified low temperature Czochralski growth of xylenol orange doped benzopheone single crystal for fabricating dual band patch antenna

Organic non-linear optical pure and xylenol orange (XO) doped benzophenone (BP) single crystals have been grown by a modified Czochralski technique. A low cost CZ system was designed and fabricated that is suitable for the growth of single crystals of low melting point organic materials. Structural analysis was performed by powder and single crystal XRD. LC-HRMS spectra reveal that the dye molecules are present in the doped crystal. The linear optical characterization was carried out by UV–vis spectroscopy. In the case of the XO doped BP crystal, two absorption peaks were found at 504nm and 620nm. The enhancement of photoluminescence intensity of blue emission was observed in the dye doped crystal. Dielectric studies reveal that the XO doped BP has shown improved a dielectric constant with low dielectric loss. A dual band compact circular patch antenna was simulated and fabricated using the XO doped crystal. Resonant frequencies of the dual bands at 4.80GHz and 9.22GHz were achieved by introducing a defect ground state in the circular patch antenna. The piezoelectric coefficient (d33) value was increased from 1 to 4 pC/N by XO dye doping, which opens up the possibilities of simultaneous transducer applications.

Effects of Doping and Electrode Contacts on Performance of Organic Light-Emitting Transistors Based on Pentacene and Tris(8-hydroxyquinoline)aluminum

Heterojunction-based organic light-emitting field-effect transistors (OLEFETs) with a top-contact, long-channel geometry were fabricated and comparatively characterized. The neutral cluster beam deposition (NCBD) method was used to successively deposit two layers of p-type pentacene and n-type tris(8-hydroxyquinoline)aluminum (Alq3). For doped OLEFETs, 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) was used as a highly fluorescent dye dopant to enhance the light-emission efficiency and change the emission color. OLEFETs revealed fine device characteristics based on deposition of highly crystalline active layers. The combination of the highly fluorescent DCM doping and asymmetric electrode configuration (Au and Li:Al or LiF/Al) exhibited efficient energy transfer and enhanced electroluminescence (EL) emission. The operating light-emission mechanisms were discussed based on EL photos acquired using a charge-coupled device (CCD) camera.

Brilliant green dye added zinc(tris) thiourea sulphate monocrystal growth with enhanced crystalline perfection, optical, photoluminescence and mechanical properties

In present work, the pure and brilliant green dye doped single crystals of nonlinear optical zinc tris(thiourea) sulfate have been grown for the first time using slow evaporation solution technique from their aqueous solutions. The powder X-ray diffraction and FT-Raman spectroscopic investigations were carried out to confirm and identify the crystal structure and vibrational modes, respectively. The strong effect of dye on crystals morphology is observed. For optical band gap analysis the diffused reflectance was measured. Two absorption bands were observed in the diffused reflectance spectrum centered at ~425 and 627 nm due to brilliant green dye. Room temperature PL study with 310 nm excitation show noticeable enhancement in UV-blue emission band centered at 348 nm due to dye doping and also the enhancement in violet-blue emission centered at 420 nm was observed. Mechanical strength was also found to be enhanced with doping. All the results show that the properties of ZTS crystals are enriched due to dye doping and can be applied in optoelectronic devices.

Role of specific and nonspecific intermolecular interaction in electro-optical response of doped 6CHBT nematic liquid crystal with azo dyes

Investigations done so far have shown that dopant material have a considerable effect on the electro-optical responses of dye-doped liquid crystal. But the type of inter or intra-molecular interaction roles in electro-optical properties and nonlinearity of doped liquid crystalline systems has uncovered. In this work, to study of the kind of molecular interaction effects on electro-optical properties of doped LC, two dyes with dissimilar interactional and functional groups were used as LC dopants. Therefore, doping these dyes into liquid crystals allows us to understand and analyze the effect of interaction type on electro-optical responses of the pure and doped samples. The electro-optical Kerr behavior, the pre-transition temperature and third order nonlinear susceptibility of pure and doped LC by two dyes with different interactional groups were having studied. The obtained results revealed that the electro-optical response of nematic liquid crystal can be strongly enhanced or decreased, depending on dopant's nature, concentration and type of specific and nonspecific interaction between doped dye and liquid crystal molecules. In other words, it will be shown that dopants molecular interactions with each other and liquid crystal molecules are important factors for controlling of electro-optical responses of dye doped liquid crystal system.

Preparation and electrochemical application of praseodymium modified TiO2-NTs/SnO2-Sb anode by cyclic voltammetry method

A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltammetry(CV). The methyl orange(MO)aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseodymium oxide was successfully doped into the SnO2-Sb film by CV method. Due to the doped Pr, the oxygen evolution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The Ct /C0(φ) was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.

FRET acceptor suppressed single-particle photobleaching in semiconductor polymer dots.

Brightness and photostability are key parameters for fluorescent probes in optical imaging. This Letter describes Förster resonance energy transfer (FRET) as a useful strategy to enhance the photostability of fluorescent nanoparticles. Small molecules as FRET acceptors were doped into semiconductor polymer dots (Pdots), yielding apparent suppression of their rapid photobleaching in single-particle imaging. For 20nm-diameter particles, the photobleaching percentage decreased from 71.8% to 47.2% after dye doping, while the single-particle brightness remained unchanged. The photostability of large Pdots was also enhanced by FRET at the expense of a moderate decrease in per-particle brightness as compared to the pure Pdots. This study indicates that FRET is a facile, yet effective, approach to mediate the brightness and photostability of fluorescent nanoparticles. Considering the combined factors of brightness and photostability, the dye-doped Pdots of ∼20 nm diameter are the most suitable for long-term imaging and tracking applications.

Effect of titan yellow dye on morphological, structural, optical, and dielectric properties of zinc(tris) thiourea sulphate single crystals

Abstract

Light-induced orientation transition in nematic liquid crystalline polymer

Optical orientation in transparent nematic liquid crystalline polymer (NLCP) was observed for the first time. In NLCP with dye dopant, the light-induced second-order orientation transition being an analogue of the Freedericksz transition in low-frequency fields is found. The transition threshold is ~10 μW which is lower than the threshold of the light-induced Freedericksz transition in low-molecular nematics by four orders ofmagnitude and is lower than the characteristic value for low-molecular nematics with dye dopant by two orders of magnitude.

Hydrogen bonding intermolecular effect on electro-optical response of doped 6PCH nematic liquid crystal with some azo dyes

Previous studies on the electro-optical responses of dye-doped liquid crystal have shown that dopant material have a considerable effect on their electro-optical responses. Despite the studies carried out on electro-optical properties of dye-doped liquid crystal, no attention has been paid to study of the interaction and structural effects in this procedure. In this paper, linear dyes and with similar structure were selected as dopants. The only difference in used dyes is the functional groups in their tails. So, doping of these dyes into liquid crystals determines the influence of interaction type on electro-optical behaviours of the doped systems. Therefore, in this work, two aminoazobenzene (“A-dye”: hydrogen bond donor) and dimethyl-aminoazobenzene (“B-dye”) dyes with different compositional percentages in liquid crystal host were used. Electro-optical Kerr behaviour, the pre-transition temperature and third order nonlinear susceptibility were investigated. The obtained results effectively revealed that type of interactions between the dye and liquid crystal is determinative of behavioral difference of doped system, compared to pure liquid crystal. Also, pre-transitional behaviour and thereupon Kerr electro-optical responses were affected by formed interactions into doped systems. In other words, it will be shown that addition of any dopants in liquid crystal, regardless of the nature of interactions, cannot cause appropriate electro-optical responses. In fact, type of dye, nature of interactions between dopant and liquid crystalline host as well as concentration of dye are the key factors in selecting the appropriate liquid crystal and dopant dye.

Hyperbranched Polyglycerol‐Doped Mesoporous Silica Nanoparticles for One‐ and Two‐Photon Activated Photodynamic Therapy

Two‐photon activated photodynamic therapy (TPA‐PDT) is a recently developed technique that shows a potential for medical application. In contrast to traditional one‐photon activated PDT, TPA‐PDT can increase the treatment depth and decrease the damage to healthy tissue by using a near‐infrared two‐photon laser. However, this technique also suffers from the fact that approved photosensitive drugs have a low two‐photon absorption cross section. In this study, it is demonstrate that doped polyglycerol mesoporous silica nanoparticles can carry a photosensitizer, Rose bengal, and can be applied in one‐ and two‐photon PDT. TPA dye‐doped mesoporous silica nanoparticles have been synthesized using a surfactant‐free route, which can be considered a TPA‐PDT platform after loading normal photosensitive drugs. The doped TPA dyes in the silica nanoparticles can transfer energy to the loading drugs via an intraparticle fluorescence resonance energy transfer (FRET) mechanism. The fluorescence lifetime and confocal laser scanning microscopy (CLSM) images obtained under different conditions demonstrated a FRET effect through both one‐ and two‐photon activated modes. The results of cytotoxicity experiments proved that this TPA‐PDT system could induce cellular apoptosis under one‐ or two‐photon irradiation. This system in principle extends the application range of TPA‐PDT.

Incorporation of diketopyrrolopyrrole dye to improve photovoltaic performance of P3HT:PC71BM based bulk heterojunction polymer solar cells

Ternary blend solar cells have been intensively studied in recent years to harvest more photons over the near-IR region. In this work, the effects of adding a diketopyrrolopyrrole dye (py-DPP) into a conventional P3HT:PC71BM based bulk heterojunction photovoltaic cell are investigated. The near infrared absorption of the blend is enhanced by the doped py-DPP dye, leading to more than 20% increased power conversion efficiency compared to the P3HT:PC71BM binary system. The highest efficiency of 4.05% is achieved for a P3HT:PC71BM blend with 2.4 wt % of py-DPP.

Multicolored Polyanilines Doped by Different Acid Dyes and Their Electrochromic Property

Multicolored polyanilines (PANIs) are synthesized by using different acid dyes containing sulfonic acid group as the functional dopant. It is found that the FTIR spectra of the acid dye doped PANI and pure PANI are similar with each other, which are all doped state PANI, and the new arising peaks indicate the acid dyes existing in the PANI molecular. The UV-Visible spectra show that the different acid dye doped PANI present different colors as the effect of the chromophore of the acid dye. From the CV curves, it is clear that all the acid dye doped PANIs exist two pairs of oxidation and reduction peaks with vivid reversibly multicolor changes from light color (-0.5~0V) to dark color (0~0.8V). It is shown that acid dye doping is an effective method to broaden the color change range of the electrochromic mateials.

Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells

Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability.

Electrochromic Porperties of Fluorescent Dye Doped Poly(3,4-ethylenedioxythiophene) with Different Polymerization Times

The electrochromic properties of an electrochemical polymerized composite consisted of poly (3,4-ethylenedioxythiophene) doped with fluorescent yellow dye (PEDOT-FY) with different polymerization time are reported. The structures of PEDOT-FY were characterized via cycle voltammograms and spectroelectrochemistry. The PEDOT-FY films can appears orange-yellow and purple in the neutral state, and yellow-green and deep green in the oxidized state. Polymerizing for 6 min, the PEDOT-FY film comes out a new pair of oxidative and reductive peaks around 0.3V and-0.15V. In addition, the PEDOT-FY films also have short response times. It is shown that acid dye doping is an effective method to broaden the color change range of the electrochromic mateials.

Electrochromic Properties of Acid Dye Doped Poly(3,4-ethylenedioxythiophene) by Electropolymerization.

The electrochromic properties of an electrochemical polymerized composite consisted of poly(3,4-ethylenedioxythiophene) doped with acid red G (PEDOT-ARG) are reported. The structures of PEDOT-ARG were characterized via cycle voltammograms, spectroelectrochemistry and colorimetric analysis. Film of the PEDOT-ARG composites switches from aubergine in the reduction state to light blue in the oxidized state, which is different from the pure PEDOT of dark blue (-0.8 V) and light blue (1.0 V). Because of the big molecule of acid red G as the dopant, the response time reaching 90% of the full optical contrast of PEDOT-ARG was 5.7 s for the oxidation process and 5.4 s for the reverse reduction process, which is a little slower than the pure PEDOT. Additionally, the colorimetric analysis results show that components of red in PEDOT-ARG films become stronger than the pure PEDOT films at the whole electrochromic process. It is shown that acid dye doping is an effective method to broaden the color change range of the electrochromic materials.

Performance of crystal violet doped triglycine sulfate single crystals for optical and communication applications

Single crystals of 0.01 and 0.02 mol% crystal violet dye doped triglycine sulfate (NH2CH2COOH)3·H2SO4 (TGS) have been grown by a slow evaporation technique. Enhanced dielectric, optical, thermal and mechanical properties have been achieved by dye doping. Monoclinic structures showing particular coloring patterns and morphology change with dye concentration were obtained. Various functional groups and dye incorporation in the grown crystals were confirmed qualitatively by FTIR and Raman analysis. A significant increase in Curie temperature from 50 to 55 °C with a decrease in maximum permittivity has been observed. The UV-vis spectra showed an increased transmittance window and an increased optical band gap from 5.61 to 6.11 eV as a result of doping. An increase in the sharpness and intensity of the photoluminescence peak with a blue shift has been observed in doped crystals. The thermal stability and the decomposition temperature were found to increase by about 10 °C in 0.01 mol% dye doped TGS. The mechanical strength of the grown crystals was estimated by the Vickers microhardness test and was found to be high for dye doped TGS. A high piezoelectric charge coefficient d33 of 16 pC N−1 was observed for pure TGS which decreased as a result of the dye effect. The fabrication of a patch antenna was carried out after simulating its resonant frequency, making it suitable for telecommunication applications.