Chalcogenide Hybrid Research Articles

Phase‐Shifted Bragg Gratings from High Refractive Index Chalcogenide Hybrid Inorganic/Polymers: Fabrication and Thermo‐Optic Characterization

AbstractIn this study, the first fabrication of phase‐shifted Bragg gratings utilizing chalcogenide hybrid inorganic/organic polymers (CHIPs) is presented based on poly(sulfur‐random‐(1,3‐isopropenylbenzene) to measure the thermo‐optic coefficient (TOC) of this new class of optical polymers. The unique properties of CHIPs, such as high index contrast and low optical losses, are leveraged to fabricate Bragg gratings that enable precise determination of the TOC and glass transition temperature (Tg) of these polymers. The optical measurement introduces a novel technique to measure the TOC and Tg of optical polymers which can be difficult to determine using traditional methods such as differential scanning calorimetry (DSC) after fabrication into photonic device constructs. The findings demonstrate that CHIPs exhibit low thermo‐optic (TO) effects, making them exceptionally well‐suited for the development of thermally stable photonic integrated circuits.

Fabrication of Plastic Optics from Chalcogenide Hybrid Inorganic/Organic Polymers for Infrared Thermal Imaging

AbstractThe development of infrared (IR) plastic optics for infrared thermal imaging, particularly, in the long‐wave IR (LWIR) spectrum (7–14 µm) is an area of growing technological interest due to the potential advantages associated with plastic optics (e.g., moldability and low cost). The development of a new class of optical polymers, chalcogenide‐based inorganic/organic hybrid polymers (CHIPs) derived from the inverse vulcanization of elemental sulfur, has enabled significant improvements in IR transparency due to reduction of IR absorbing organic comonomer units. The vast majority of effort has focused on new chalcogenide hybrid polymer synthesis and optical property improvements (e.g., refractive index, Abbe number, and LWIR transmission); however, fabrication and IR imaging methodology to prepare optical components has not been demonstrated, which remains critical to develop viable IR plastic optics. A new methodology is reported to fabricate optical components and evaluate LWIR imaging performance of this emerging class of optical polymers. New diffractive flat optics with a Fresnel lens design for these materials have been developed, along with a basic LWIR imaging system to evaluate CHIPs for LWIR imaging. This system‐based approach enables correspondence of copolymer structure‐property correlations with LWIR imaging performance, along with demonstration of room temperature LWIR imaging.

Characterization of the optical and electronic properties of chalcogenide hybrid inorganic/organic polymer thin films

Chalcogenide hybrid inorganic/organic polymers (CHIPs) are a new class of optical polymeric materials for imaging and photonic applications due to their high refractive indices and high optical transmission at visible and infrared wavelengths. In this study, we characterize these polymers to study the refractive index and delve into the electronic properties by way of measurements of their dielectric constants. Ellipsometry is used to determine the refractive indices for wavelengths from 500 nm to 12 µm, while we use capacitance measurements on thin film capacitors with a range of areas to find the dielectric constant. The results are in line with expectations based on the sulfur composition of the polymers-indices range from 1.7 to 1.85, and dielectric constants range from 2.6 to 3. With these measurements, these sulfur polymer materials are established to be good candidates for optical and photonic applications, particularly with respect to telecommunications. The dielectric constants suggest that applications such as electro-optic devices and capacitors may also be viable.

Design and fabrication of mixed phase transition metal chalcogenide hybrid composite (M = Ni & Co) for Pt-free efficient dye-sensitized solar cell applications

Design and fabrication of mixed phase transition metal chalcogenide hybrid composite (M = Ni & Co) for Pt-free efficient dye-sensitized solar cell applications

High Refractive Index Chalcogenide Hybrid Inorganic/Organic Polymers for Integrated Photonics

AbstractOptical polymer‐based integrated photonic devices are gaining interest for applications in optical packaging, biosensing, and augmented/virtual reality (AR/VR). The low refractive index of conventional organic polymers has been a barrier to realizing dense, low footprint photonic devices. The fabrication and characterization of integrated photonic devices using a new class of high refractive index polymers, chalcogenide hybrid inorganic/organic polymers (CHIPs), which possess high refractive indices and lower optical losses compared to traditional hydrocarbon‐based polymers, are reported. These optical polymers are derived from elemental sulfur via the inverse vulcanization process, which allows for inexpensive monomers to be used for these materials. A facile fabrication strategy using CHIPs via lithography is described for single‐mode optical waveguides, Y junction splitters, multimode interferometers (MMIs), and high Q factor ring resonators, along with device characterization. Furthermore, propagation losses of 0.4 dB cm−1 near 1550 nm wavelength, which is the lowest measured loss in non‐fluorinated optical polymer waveguides, coupled with the benefits of low cost materials and manufacturing are reported. Ring resonators with Q factor on the order of 6 × 104 and cavity finesse of 45, which are some of the highest values reported for optical polymer‐based ring resonators, are also reported.

Promising Chalcogenide Hybrid Copolymers for Sustainable Applications as Bio-lubricants and Metal Adsorbents

Inverse vulcanization has emerged as a reaction to achieve hybrid inorganic–organic polymeric materials, which allows us to use the high amount of sulfur produced during refining crude oil as a raw material. In this study, a gamut of copolymers has been formulated using a quantitative atom economy, that is, elemental sulfur and castor oil (CO), as can be seen from the appearance of gels to crystalline copolymers. The physical and chemical characterization has been carried out using techniques such as Fourier transform infrared spectroscopy, NMR, differential scanning calorimetry, and thermogravimetric analysis. Furthermore, two types of copolymers have been selected to test their capabilities in different applications. Copolymers with S ratios higher than 30% have been tested for water remediation, with high removal rates for metals such as lead and cadmium. Although copolymers with a percentage of up to 10% sulfur have been tested as bio-based lubricants, showing improvements in terms of viscosities compared to the initial vegetable oil.

Dynamic Covalent Polymerization of Chalcogenide Hybrid Inorganic/Organic Polymer Resins with Norbornenyl Comonomers

Elemental sulfur (S8) is an inexpensive chemical feedstock for polymeric materials but has the disadvantages of poor solubility in organic media and inferior physical properties in the elemental form. We report on the preparation of organosulfur chalcogenide hybrid inorganic/organic polymer (CHIPs) based on bifunctional norbornene comonomers using dynamic covalent polymerization (DCP). A poly(sulfur-random-styrene) (p(S-r-Sty)) resin was utilized to address the limited solubility/ miscibility of norbornene-containing comonomers in liquid sulfur. This report demonstrated the ability to expand the scope of organic comonomers to prepare organosulfur CHIPs from elemenatal sulfur using a combination of inverse vulcanization and dynamic covalent polymerization.

Infrared Fingerprint Engineering: A Molecular-Design Approach to Long-Wave Infrared Transparency with Polymeric Materials.

Optical technologies in the long-wave infrared (LWIR) spectrum (7-14 μm) offer important advantages for high-resolution thermal imaging in near or complete darkness. The use of polymeric transmissive materials for IR imaging offers numerous cost and processing advantages but suffers from inferior optical properties in the LWIR spectrum. A major challenge in the design of LWIR-transparent organic materials is that nearly all organic molecules absorb in this spectral window which lies within the so-called IR-fingerprint region. We report on a new molecular-design approach to prepare high refractive index polymers with enhanced LWIR transparency. Computational methods were used to accelerate the design of novel molecules and polymers. Using this approach, we have prepared chalcogenide hybrid inorganic/organic polymers (CHIPs) with enhanced LWIR transparency and thermomechanical properties via inverse vulcanization of elemental sulfur with new organic co-monomers.

Infrared Fingerprint Engineering: A Molecular‐Design Approach to Long‐Wave Infrared Transparency with Polymeric Materials

AbstractOptical technologies in the long‐wave infrared (LWIR) spectrum (7–14 μm) offer important advantages for high‐resolution thermal imaging in near or complete darkness. The use of polymeric transmissive materials for IR imaging offers numerous cost and processing advantages but suffers from inferior optical properties in the LWIR spectrum. A major challenge in the design of LWIR‐transparent organic materials is that nearly all organic molecules absorb in this spectral window which lies within the so‐called IR‐fingerprint region. We report on a new molecular‐design approach to prepare high refractive index polymers with enhanced LWIR transparency. Computational methods were used to accelerate the design of novel molecules and polymers. Using this approach, we have prepared chalcogenide hybrid inorganic/organic polymers (CHIPs) with enhanced LWIR transparency and thermomechanical properties via inverse vulcanization of elemental sulfur with new organic co‐monomers.

Recent advances in the polymerization of elemental sulphur, inverse vulcanization and methods to obtain functional Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs)

Recent developments in the polymerization of elemental sulfur, inverse vulcanization and functional Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs) are reviewed.

Nonlinear optical properties of chalcogenide hybrid inorganic/organic polymers (CHIPs) using the Z-scan technique

The linear and nonlinear optical behavior of novel sulfur based polymer materials are evaluated at the optical communication wavelength, 1550 nm. These polymers are attractive for near-IR (NIR) and mid-IR applications. The two photon absorption (TPA) coefficient (β) and second order refractive index (n2) of chalcogenide hybrid inorganic/organic polymers (CHIPs) from poly(sulfur-random-(1,3-diisopropenylbenzen) (poly(S-r-DIB)) are measured via the Z-scan technique. In this study, we investigated the linear and nonlinear optical behavior of two types of CHIPs where the weight percentage of sulfur is varied (poly(S50%-r-DIB50%) and poly(S70%-r-DIB30%)). The TPA coefficients for poly(S50%-r-DIB50%) and poly(S70%-r-DIB30%) obtained were 0.11 cm/GW and 0.063 cm/GW, respectively. The n2 for poly(S50%-r-DIB50%) and poly(S70%-r-DIB30%) was measured and determined to be 2.45 × 10−15 cm2/W and 3.06 × 10−15 cm2/W, respectively, and are in good agreement with Miller’s rule prediction. These materials exhibit low cost, low temperature processing, high transparency in the near to mid-IR range (except a few interval ranges) and relatively high refractive index, providing a unique set of properties for optics and photonics device applications.

One Dimensional Photonic Crystals Using Ultrahigh Refractive Index Chalcogenide Hybrid Inorganic/Organic Polymers.

We report on the fabrication of wholly polymeric one-dimensional (1-D) photonic crystals (i.e., Bragg reflectors, Bragg mirrors) via solution processing for use in the near (NIR) and the short wave (SWIR) infrared spectrum (1-2 μm) with very high reflectance (R ∼ 90-97%). Facile fabrication of these highly reflective films was enabled by direct access to solution processable, ultrahigh refractive index polymers, termed, Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs). The high refractive index (n) of CHIPs materials (n = 1.75-2.10) allowed for the production of narrow band IR Bragg reflectors with high refractive index contrast (Δn ∼ 0.5) when fabricated with low n polymers, such as cellulose acetate (n = 1.47). This is the highest refractive index contrast (Δn ∼ 0.5) demonstrated for an all-polymeric Bragg mirror which directly enabled high reflectivity from films with 22 layers or less. Facile access to modular, thin, highly reflective films from inexpensive CHIPs materials offers a new route to IR Bragg reflectors and other reflective coatings with potential applications for IR photonics, commercial sensing, and LIDAR applications.

Retraction: Multifunctional fluorescent chalcogenide hybrid nanodots (MoSe2:CdS and WSe2:CdS) as electro catalyst (for oxygen reduction/oxygen evolution reactions) and sensing probe for lead

Retraction of ‘Multifunctional fluorescent chalcogenide hybrid nanodots (MoSe2:CdS and WSe2:CdS) as electro catalyst (for oxygen reduction/oxygen evolution reactions) and sensing probe for lead’ by Paramita Karfa et al., J. Mater. Chem. A, 2017, 5, 1495–1508.

Hybrid Sulfur−Selenium Co‐polymers as Cathodic Materials for Lithium Batteries

AbstractLithium−sulfur is being explored as a promising battery technology, owing to due to advantages compared to the actual Li ion. However, sulfur cathode materials have critical drawbacks that limit their battery performance. Recently, the atomic combination of sulfur with selenium has shown a synergetic effect in terms of capacity and rate capability; nevertheless, a high‐energy and non‐scalable method was used to prepare the sulfur−selenium cathodes. In this work, the synthesis of sulfur−selenium hybrid co‐polymers is reported by using a low‐energy and scalable inverse vulcanization method. Thus, a series of chalcogenide hybrid inorganic/organic materials were synthesized by varying the sulfur, selenium, and organic content. The chalcogenide part was characterized by using Raman spectroscopy and 77Se NMR, showing a random distribution of selenium within the sulfur segments. The organic part and the hybrid were further characterized by using 1H NMR, DSC, and TGA approaches, confirming the typical structure of inverse vulcanized co‐polymers. These hybrids were easily processed by conventional cathode fabrication methods and electrochemically characterized. The presence of selenium slightly affected the cyclic voltammetry of the materials, maintaining the typical features to be used as cathodes in lithium−sulfur batteries. Interestingly, the sulfur−selenium cathodes showed an enhanced C‐rate capability and high cycling stability. The optimum co‐polymer composition was 5 to 7.5 mol % of Se within S and 10 wt % of organic co‐monomer, showing initial capacity values of 860 and 880 mAh g−1, respectively, for a moderate C‐rate of C/5. These polymers showed the lowest capacity loss per cycle, 0.14 and 0.4 %, in comparison with the 0.6 % of capacity loss of the polymer with bare sulfur. Interestingly, for a lithium−sulfur cell, the best performing material shows an excellent capacity value of 550 mAh g−1 at high C rate of 1C.

Chalcogenide Hybrid Inorganic/Organic Polymers: Ultrahigh Refractive Index Polymers for Infrared Imaging.

We report on the preparation of ultrahigh refractive index polymers via the inverse vulcanization of elemental sulfur, selenium, and 1,3-diisopropenylbenzene for use as novel transmissive materials for mid-infrared (IR) imaging applications. Poly(sulfur-random-selenium-random-(1,3-diisopropenylbenzene)) (poly(S-r-Se-r-DIB) terpolymer materials from this process exhibit the highest refractive index of any synthetic polymer (n > 2.0) and excellent IR transparency, which can be directly tuned by terpolymer composition. Sulfur or selenium containing (co)polymers prepared via inverse vulcanization can be described as Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs) and are polymeric analogues to wholly inorganic Chalcogenide Glasses (ChGs), which are commonly used as transmissive materials in mid-IR imaging. Finally, we demonstrate that CHIPs composed of (poly(S-r-Se-r-DIB) can be melt processed into windows that enabled high quality mid-IR thermal imaging of human subjects and highly resolved imaging of human vasculature.

Retracted Article: Multifunctional fluorescent chalcogenide hybrid nanodots (MoSe2:CdS and WSe2:CdS) as electro catalyst (for oxygen reduction/oxygen evolution reactions) and sensing probe for lead

We present the multi-functional application of transition metal chalcogenides nanohybrid dots as bifunctional electrocatalyst for OER/ORR and fluorescent probes for Pb2+.

Colloidal Heterostructured Nanocrystals for Solar Energy Conversion Applications

To meet high demand of clean and reusable energy e.g., solar energy, a new type of nanomaterials is emerging, i.e., heterostructured nanomaterials. It combines different kinds of materials with different size and morphologies into a system and hence offers different optical, electrical and optoelectronic properties from its components. And it enables multifunctional capabilities as well in one material, in the meanwhile shows improved properties and/or novel phenomena during building such complex “nanotoys” towards potential applications for solar energy conversion (e.g., photocatalysis). Prevailing examples like metal–metal chalcogenide hybrid nanomaterials and most recent progress in heterostructured nanomaterials as well with a focus on those with asymmetric morphologies are discussed in this review. Moreover, metal–metal oxides with anisotropic structures and nanojunctions formed between those semiconducting nano blocks are also outlined, followed by their distinct properties and applications in photocatalytic reactions of water splitting and CO 2 reduction to H 2 and CO 2 respectively.