Hybrid Optical Materials Research Articles

Doping and plasmonic Raman enhancement in hybrid single walled carbon nanotubes films with embedded gold nanoparticles

Novel optical hybrid materials can be produced with carbon nanotubes and metallic nanoparticles. Such hybrids may allow coupling between plasmons in metals and excitons in nanotubes. We develop novel hybrid materials in the form of thin films using vacuum filtration, where gold nanoparticles are embedded into the entire volume of the nanotube film, not only on the top of the film. After producing semiconducting and metallic hybrids, we investigate their electronic properties. Free charge carriers in metallic nanoparticles extend into nanotubes, resulting in the doping effect. The doping effect manifests in changes the phonon energy and lifetime, scaling with gold nanoparticle concentration. We implement statistical Raman analysis and determine 20 meV p-doping. The statistical data were cross-correlated with parameters of the 2D and G modes, which helped to clearly disentangle doping and strain. Further, we studied optical properties of the films. The gold nanoparticles enhance the CNTs Raman scattering efficiency. The enhancement is wavelength dependent, as confirmed by resonance Raman spectroscopy on radial breathing modes. The enhancement factors vary from 2 to 3.5 times, with maximum at 1.7 eV. The shapes of enhanced resonance Raman profiles were interpreted with the fifth-order perturbation theory incorporating plasmonic effect.

Changes in Optical Properties upon Dye-Clay Interaction: Experimental Evaluation and Applications.

The development of hybrid materials with unique optical properties has been a challenge for the creation of high-performance composites. The improved photophysical and photochemical properties observed when fluorophores interact with clay minerals, as well as the accessibility and easy handling of such natural materials, make these nanocomposites attractive for designing novel optical hybrid materials. Here, we present a method of promoting this interaction by conjugating dyes with chitosan. The fluorescent properties of conjugated dye–montmorillonite (MMT) hybrids were similar to those of free dye–MMT hybrids. Moreover, we analyzed the relationship between the changes in optical properties of the dye interacting with clay and its structure and defined the physical and chemical mechanisms that take place upon dye–MMT interactions leading to the optical changes. Conjugation to chitosan additionally ensures stable adsorption on clay nanoplatelets due to the strong electrostatic interaction between chitosan and clay. This work thus provides a method to facilitate the design of solid-state hybrid nanomaterials relevant for potential applications in bioimaging, sensing and optical purposes.

Janus Oligomers Demonstrating Full‐Spectrum Visible Light Reflection and Tunable Photoluminescence towards Dual‐Mode Dynamic Anti‐Counterfeiting

AbstractStimulus‐responsive multimodal optical materials demonstrating tunable optical behaviors possess significant application in optoelectronic materials and devices. Introducing fluorescent elements into liquid crystal structures is a common strategy. The design of hybrid optical structure at molecular level is seldom reported. Herein, novel Janus oligomers (JOs) combining the chiral nematic liquid crystalline (CNLC) units and the photoluminescent (PL) units on organosilicon oligomers by molecular grafting are proposed. The as‐prepared JOs display brilliant visible light reflection originating from the chiral arrangement of the CNLC segments. The discrete pyrene chromogenic segments in the CNLC matrix enable the quantum yield and PL lifetime of JOs to be up to 38.58% and 68.45 ns. Furthermore, the JOs present dual‐mode thermochromic performances, the blue‐shift reflection across the full‐spectrum visible light region, and the highly sensitive PL evolution. The JOs can be manufactured into dynamic anti‐counterfeiting patterns with fast and reversible response by screen printing. The Janus optical structure enabled by chemically coupling different optical elements at the molecular level provides a templated strategy to create the next generation of intelligent hybrid optical materials.

Preparation and properties of high refractive index UV-cured titanium hybrid optical materials

In this study, a new synthetic route was developed to prepare UV-cured titanium hybrid optical materials. Transparent high refractive index titanium hybrid optical materials were prepared by means of non-hydrolyzed sol-gel and UV curing. The experimental results show: titanium was successfully introduced into the silicone chain in the form of Ti-O-Si chemical bonds. The materials have high light transmittance (>95%) in the visible light region, high thermal stability and tunable refractive index (1.6533–1.8145) at 486 nm. Our study provides a new ideal for preparing high refractive index UV-cured titanium hybrid optical materials for potential optical applications.

Blue–green color-tunable emissions in novel transparent Sr2LuF7:Eu/Tb glass-ceramics for WLEDs

To introduce ordered nano-structures inside a transparent amorphous matrix with superior optical and mechanical properties bears scientific and technological importance, yet limited success has been achieved. Here, via simple melting-quenching and subsequent thermal activation, we report the successful preparation of transparent nano-structured glass-ceramics embedded in Sr2LuF7 nano-crystals (∼26 nm), as evidenced by X-ray diffraction, transmission electron microscopy (TEM), and high resolution TEM. The successful incorporation of dopants into formed Sr2LuF7 nano-crystals with low phonon energy results in highly tunable blue–green photoemission, which depends on excitation wavelength, dopant type, and temperature. We found that Eu3+ and Eu2+ ions co-exist in this hybrid optical material, accompanied by the broadband blue emission of Eu2+ and sharp red emissions of Eu3+. A series of optical characterizations are summoned, including emission/excitation spectrum and decay curve measurement, to reveal the reduction mechanism of Eu3+ to Eu2+. Furthermore, near green–white photoemission is achieved via the enrichment of Tb3+/Eu3+ into crystallized Sr2LuF7 nano-crystals. The temperature-dependent visible photoemission reveals thermal activation energy increases with the precipitation of Sr2LuF7 nano-crystals in a glass matrix, suggesting better thermal stability of glass-ceramics than precursor glasses. These results could not only deepen the understanding of glass-ceramics but also indicate the promising potential of Eu3+/Tb3+-ions-doped Sr2LuF7 glass-ceramics for UV pumped white light emitting diodes (WLEDs) with good thermal stability.

Recent Advances in Hybrid Optical Materials: Integrating Nanoparticles within a Glass Matrix

AbstractGlass containing optically active nanoparticles have been manufactured for centuries. However, only in the early 1900s, the invention of ultramicroscope and development of Mie theory paved the way to discovering the occurrence of nanoparticles in glass and their special role in imparting unique optical properties to glass. This groundbreaking insight inspired scientists to extensively research such nanoparticles‐in‐glass hybrid optical materials, which led to a series of fundamental breakthroughs (e.g., invention of glass ceramics, discovery of quantum dots) and commercial successes (e.g., photosensitive glass, photochromic glass, dichromic polarizer). Over the past decades, a new wave of research in this area has been initiated by opportunities of incorporating a large variety of synthetic nanoparticles in glass, which promises the development of advanced functional devices for lighting, display, smart window, data storage, and sensing applications. Recent development of various approaches of fabricating nanoparticles‐in‐glass hybrid optical materials and postmodifying nanoparticles that are embedded in glass is reviewed. The state‐of‐the‐art techniques relevant to controlling the dispersion, distribution, orientation, and nanostructure of nanoparticles in glass, as well as manipulating the macroscopic performance of the hybrid materials are discussed. Examples of applications with promising pathway to commercially viable devices based on hybrid optical materials are outlined.

Preparation and spectral properties of europium hydrogen squarate microcrystals

A simple scheme for preparation of europium hydrogen squarate octahydrate microcrystals, Eu(HSq)3·8H2O is demonstrated. The microcrystalline powders obtained have a potential application as non-centrosymmetric and UV radiation – protective hybrid optical material. The site-symmetry of the Eu – ion is C2V or lower, obtained from diffuse reflectance spectra. The formation of europium hydrogen squarate is supported by IR – spectroscopy, UV–vis spectroscopy, chemical analysis and X-ray diffraction. A detailed analysis of the UV–vis and IR spectra of the micropowders prepared is presented.

Spontaneous emission intensity and anisotropy of quantum dot films in proximity to nanoscale photonic–plasmonic templates

We discuss results on spontaneous emission intensity and lifetime anisotropy of cadmium selenide quantum dot monolayer films placed in close proximity to a porous block copolymer based photonic–plasmonic two dimensional array. The porous block copolymer cylinders can be filled with metal nanoparticles and the concentration of these nanoparticles is varied to control both the photoluminescence intensity and lifetime of a layer of quantum dots placed above the template. Significant emission enhancement is achieved even for the quantum dot layer whose core lies about 1 nm above the template surface. Interestingly, polarised decay lifetime analysis indicates considerable emission anisotropy, as well for these quantum dots. Our results thus demonstrates how such hybrid optical materials can be created with controlled optical properties and suggests extension of this method to other novel two dimensional materials in combination with the photonic–plasmonic template.

The pivotal step of nanoparticle functionalization for the preparation of functional and magnetic hybrid opal films

An efficient and universal surface modification protocol for silica nanoparticles is reported for the preparation of novel hybrid optical materials.

Intercalation assembly of optical hybrid materials based on layered terbium hydroxide hosts and organic sensitizer anions guests

Abstract Optical hybrid materials based on inorganic hosts and organic sensitizer guests hold promise for a virtually unlimited number of applications. In particular, the interaction and the combination of the properties of a defined inorganic matrix and a specific sensitizer could lead to synergistic effects in luminescence enhancing and tuning. The current article focuses on the intercalation assembly of optical hybrid materials based on the layered terbium hydroxide (LTbH) hosts and organic divalent carboxylic sensitizer anion guests by a hydrothermal process. The studies on the interactions between hosts and guests indicate that the type and arrangement of organic guests in the layer spacing of the LTbH hosts can make a difference in the luminescence of the hybrid inorganic–organic materials.

Preparation and characterization of transition metal based organo-inorganic hybrid optical materials for bioassay fluorescence sensor probe

High refractive index (H.R.I.) tetravalent transition metal ion coordinated with organic co-dopant to form charge transfer complexes into the optical acrylic preform. They have been fabricated with different concentrations of transition metal ions and H.R.I. organic co-dopant and characterized. The improved photo physical properties, thermal, structure, optical, and morphology of transition metal ions into the optical acrylic preform hybrid matrix were analyzed. Transition metal ions are dispersed inside the preform matrix with nanoparticles of mesophase structural organization through charge transfer complex formation. It gives a crucial role of nano-interface properties on fluorescence bright imaging and less life time. This hybrid functional optical hybrid material has high potential use in bio-assay sensor probe.

Hybrid optical materials of plasmon-coupled CdSe/ZnS coreshells for photonic applications

A hybrid optical nanostructure of plasmon-coupled SQDs was developed for photonic applications. The coupling distances between the mono-layers of Au nanoparticles with a surface concentration of ~9.18 × 10-4 nm-2 and CdSe/ZnS SQDs with that of ~3.7 × 10-3 nm-2 were controlled by PMMA plasma etching. Time-resolved spectroscopy of plasmon-coupled SQDs revealed a strong shortening of the longest lifetime and ~9-fold PL enhancement. Polarization-resolved PL spectroscopy displayed linear polarization and depolarization at near- and far-field plasmon-coupling, respectively. The physical origin of PL enhancement could be attributable to both the large local field enhancement and the fast resonant energy transfer.

A Convenient Organic–Inorganic Hybrid Approach Toward Highly Stable Squaraine Dyes with Reduced H‐Aggregation

AbstractA generic and effective approach for solving the aggregation effect observed with optical materials in solid state or in a solution with a poor solvent was explored by designing two types of squaraine‐containing polyhedral oligomeric silsesquoixane (POSS)‐based hybrids. It is expected that incorporation of “huge” inorganic POSS nanoparticles into optical materials via covalent bonding can effectively decrease the strong dipole–dipole and π–π stacking interactions, inhibit intermolecular charge transfer between adjacent squaraine molecules, and improve optical, thermal and chemical stability of the resultant materials. Both theoretical calculations and experimental results indicate that the molecular design strategy is rational and efficacious. The resultant organic–inorganic hybrid optical materials effectively eliminate the aggregation of organic optical chromophoric groups by hindering intermolecular charge transfer and decreasing dipole–dipole and π–π stacking interaction between the chromophores, and exhibit good optical stability, i.e., the absorption peaks of H1 and H2 display only a slight blue‐shift, even in the solid. Simultaneously, the hybrids also show significantly enhanced thermal, and chemical stabilities in comparison with the precursor organic optical materials.

Effective Solution Mixing Method to Fabricate Highly Transparent and Optical Functional Organic−Inorganic Nanocomposite Film

The organic−inorganic hybrid optical materials with a high transmittance of visible-light have shown great potential applications. However, it is still in challenge to maintain the transparency of optical materials when the inorganic nanoparticles (NPs) are introduced into the polymer matrix because of Rayleigh scattering caused by the severely aggregation of NPs, which is a huge obstacle for its applications. This article reports a transparent “solution” mixing method to fabricate a highly transparent nanocomposite film of zinc oxide (ZnO)/poly (methyl methacrylate)-co-poly (styrene) (PMMA-PS) with the novel UV-shielding properties. The transparent “solution” containing nanoparticles was prepared by phase-transfer of ZnO NPs suspension in hexane to NPs dispersion in toluene with surface modifier. The latter dispersion had the complete transparency as a solution (so-called “solution”). It was found that the incorporation of ZnO NPs not only provided UV-shielding ability to the PMMA-PS nanocomposite film w...

New photosensitive colorless polyimide-silica hybrid optical materials: Synthesis, properties and patterning

We report the synthesis, properties, and patterning of non-fluorinated photosensitive polyimide-silica hybrid optical materials. End-functionalized ionic salt photosensitive poly(1,4-bis(3,4-dicarboxyphenoxy)-2,5-ditertbutylbenzene-dianhydride-co-oxydianiline) (DDBBDA-ODA)/2-methylacrylic acid 2-dimethylamino ethyl ester (MDAE) was prepared first. It was then reacted with tetramethoxysilane (TMOS)-derived silica sol and 3-methacryloxypropyl trimethoxysilane (MSMA) to obtain the ultralow volume shrinkage hybrid optical materials. The experimental results showed the nano-silica domain and the crosslinked structures significantly enhanced the thermal properties, such as the glass transition temperature and coefficient of thermal expansion. The prepared hybrid film not only exhibited high transparency in the visible region but also had tunable refractive index, low birefringence and optical loss by introducing the silica moiety. The SEM image suggested the prepared photosensitive hybrid materials could obtain fine lithographical patterns with an excellent dimensional stability. The combination of excellent optical properties and dimensional stability suggested the potential applications of the prepared hybrid materials for optoelectronic device applications.

Synthesis, properties, and anti-reflective applications of new colorless polyimide-inorganic hybrid optical materials

We report the synthesis, properties and anti-reflective applications of new colorless polyimide-inorganic hybrid thin films prepared from 1,4-bis(3,4-dicarboxyphenoxy)-2,5-di-tert-butylbenzene dianhydride (DDBBDA)/oxydianiline (ODA) with silica or titania precursors. The experimental results suggest that the prepared hybrid films have good thermomechanical properties, excellent transparence, tunable refractive indices of 1.550–1.847, and low optical birefringence. The nanocrystalline titania domain size analyzed form TEM and XRD is in the range of 10–20 nm in the hybrid materials. Three-layer anti-reflective films on glass or polymer substrates processed from the hybrid precursors have a relatively low reflection of less than 0.5% in the visible range. These results indicate that the newly prepared colorless polyimide-inorganic hybrid materials have potential applications for optical devices.

Dendronized organic–inorganic nonlinear optical hybrid materials with homogeneous morphology

To obtain excellent thermal stability, a series of dendronized organic–inorganic hybrids were synthesized and characterized. Dendronized alkoxysilane dyes were prepared via the ring opening addition reaction of azetidine-2,4-dione of chromophore-containing dendrons, with 3-aminopropyltriethoxysilane. Subsequently, the precursor, dendronized alkoxysilane dyes could be hydrolyzed and copolymerized with phenyltriethoxysilane (PTEOS) with the weight ratios of 1:1, 1:3, 1:5 and 1:7 in the presence of water and formic acid. After curing and poling process, organic–inorganic hybrid thin films with homogeneous morphology were obtained. Electro-optical (EO) coefficients (r33) of 2.9–13.0pm/V were achieved. Due to the site-isolation effect, the sample with high generation dendrons possessed a higher EO coefficient/dye content ratio. In addition, because of the improved miscibility between organic and inorganic segments due to highly branched hydrogen bonding-rich dendrons, NLO polymers with waveguide properties ranging from 3.2 to 4.2dB/cm at 1310nm were obtained. These dendronized organic–inorganic NLO hybrids also show greatly enhanced temporal stability at 100°C.

Preparation and optical and electrical evaluation of bulk SiO 2 sonogel hybrid composites and vacuum thermal evaporated thin films prepared from molecular materials derived from (Fe, Co) metallic phthalocyanines and 1,8 dihydroxiantraquinone compounds

Semiconducting molecular material of PcFe(CN)L1 and PcCo(CN)L1 (L1 = 1,8 dihydroxianthraquinone), PcFe(CN)L2 and PcCo(CN)L2 (L2 = double potassium salt of 1,8 dihydroxianthraquinone) have been successfully used to prepare thin film and bulk sol–gel hybrid optical materials. These samples were developed according to the vacuum thermal evaporation technique and the catalyst-free sonogel route, respectively. Thin films samples were deposited on Corning glass substrates and crystalline silicon wafers and were characterized by infrared (FTIR), Raman and ultraviolet-visible (UV–vis) spectroscopies. IR-spectroscopy and Raman studies unambiguously confirmed that the molecular material thin films exhibit the same intra-molecular bonds, which suggests that the thermal evaporation process does not alter these bonds significantly. These results show that it is possible to deposit molecular materials of PcFe(CN)L2 and PcCo(CN)L2 on Corning glass substrates and silicon wafers. From the UV–vis studies the optical band gap ( E g) was evaluated. The effect of temperature on conductivity was also evaluated in these samples. Finally, the studied molecular systems dissolved at different concentrations in tetrahydrofuran (THF) were successfully embedded into a highly pure SiO 2 sonogel network generated via sonochemical reactions to form several solid state, optically active sol–gel hybrid glasses. By this method, homogeneous and stable hybrid monoliths suitable for optical characterization can be produced. The linear optical properties of these amorphous bulk structures were determined by the Brewster angle method and by absorption-, Raman- and photoluminescent (PL)-spectroscopies, respectively.

Hybrid Optical Material with Nanoparticles at High Concentrations in UV-Curable Polymers – Technology and Properties

Optical hybrid materials with comparable concentrations of inorganic nanoparticles and polymer matrix components are studied. Materials are homogeneous and have good optical properties and processability. Effects related to a high concentration of nanoparticles in the polymer are discussed. Optical and rheological properties of these materials are investigated.

Introduction to the Issue on Organic and Inorganic Photonic Materials

The 14 papers published on this issue cover a broad range of photonic materials that are summarized in the following five sections: 1) Nonlinear Optical Materials; 2) Photovoltaics; 3) Infrared Optical Materials and Structures; 4) Hybrid or Nonconventional Optical Materials; and 5) Phosphor, Lighting and Display Materials.