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Xing-Hua Zhou

Bio: Xing-Hua Zhou is an academic researcher from University of Washington. The author has contributed to research in topics: Chromophore & Poling. The author has an hindex of 15, co-authored 21 publications receiving 1296 citations. Previous affiliations of Xing-Hua Zhou include University of Southern California.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors report broad bandwidth, 0.1-10 THz time-domain spectroscopy of linear and electro-optic polymers for broadband THz applications.
Abstract: We report broad bandwidth, 0.1–10 THz time-domain spectroscopy of linear and electro-optic polymers. The common THz optical component materials high-density polyethylene, polytetrafluoroethylene, polyimide (Kapton), and polyethylene cyclic olefin copolymer (Topas) were evaluated for broadband THz applications. Host polymers polymethyl methacrylate, polystyrene, and two types of amorphous polycarbonate were also examined for suitability as host for several important chromophores in guest-host electro-optic polymer composites for use as broadband THz emitters and sensors.

375 citations

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TL;DR: In this paper, epoxyisophorone ring-opening chemistry was used to incorporate the butylthio group to the phenyltetraene bridge of highly efficient nonlinear optical chromophores in high overall yield.
Abstract: We have successfully utilized epoxyisophorone ring-opening chemistry to efficiently incorporate the butylthio group to the phenyltetraene bridge of highly efficient nonlinear optical chromophores in high overall yield. By following the guidance of Dewar’s rules, the sulfur atom functions as a moderate π-accepting group at a starred position of the conjugated bridge. Several of very critical material parameters of the phenyltetraenic chromophores for device applications have been intrinsically and simultaneously improved through such a simple and straightforward engineering of molecular structures. Compared with the nonsubstituted analogue 2, thiolated chromophore 1 achieves higher molecular hyperpolarizability (34%), enhanced E-O coefficient (38%), significantly improved photochemical stability against 1O2 (by an order of magnitude), and better optical transparency (17 nm blue-shifted λmax absorption spectrum).

156 citations

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TL;DR: In this article, the authors highlight the areas of special significance in recent organic electro-optic (EO) materials development and highlight the important issues relating to applications and prospects of these advanced EO materials.
Abstract: Organic electro-optic (EO) materials are of considerable interest owing to their attractive characteristics for applications in high-speed information processing and sensing. The purpose of this review is to highlight the areas of special significance in recent organic EO materials development. Particular attention is paid to recent advances in achieving exceptional material properties (such as large optical nonlinearity and excellent stability) through rational molecular design of dipolar chromophores, supramolecular assembly of dendrimers, and click chemistry enabled control of lattice hardening of nonlinear optical polymers. Important issues relating to applications and prospects of these advanced EO materials are also briefly mentioned.

140 citations

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TL;DR: In this article, a new generation of NLO dendrimers has been developed to generate well-defined nano-objects, minimize strong intermolecular electrostatic interactions, and improve poling efficiency and stability.
Abstract: Recent developments of molecular architectural control and solid-state engineering have led to exceptionally large electro-optic (EO) activities in organic and polymeric nonlinear optical (NLO) materials. A new generation of NLO dendrimers has been developed to generate well-defined nano-objects, minimize strong intermolecular electrostatic interactions, and improve poling efficiency and stability. A facile and reliable Diels−Alder “click” reaction was applied for lattice hardening to improve physical properties of cross-linkable EO polymers. The “click” chemistry also provides means to study the relationship between EO activity, chromophore shape, and number density of the chromophore, systematically. The NLO dendrimers or polymers were used as hosts for guest chromophores to increase chromophore concentration and improve poling efficiency. A variety of nanostructured organic and polymeric materials with ultrahigh r33 values (>350 pm/V at the wavelength of 1310 nm, more than 10 times that of LiNbO3) and ...

127 citations

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TL;DR: In this paper, a review of the development of tailored organic electric-optic (OEO) materials and their applications in hybrid device systems has been reviewed, which includes the optical and/or electrical components that form intimate contact with OEO materials such as metal oxide barrier layers, solution processable passive waveguides, silicon nanoslots, and photonic CMOS chips.
Abstract: Recent development of tailored organic electric-optic (OEO) materials and their applications in hybrid device systems has been reviewed. Hybrid systems encompass the optical and/or electrical components that form intimate contact with OEO materials, such as metal oxide barrier layers, solution processable passive waveguides, silicon nanoslots, and photonic CMOS chips, etc. These systems offer unique advantages combining excellent properties and simple processing for advanced photonic device platforms. Examples include the demonstration of low-Vπ and low-loss EO modulators in hybrid polymer sol−gel waveguides, CMOS-compatible hybrid polymer/silicon slotted waveguides, and EO polymer-clad silicon nitride ring resonator modulators. This review also provides a future prospect for the development of OEO materials and their hybrid systems.

113 citations


Cited by
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Journal ArticleDOI
TL;DR: Long-range surface plasmon polaritons (LRSPPs) are optical surface waves that propagate along a thin symmetric metal slab or stripe over an appreciable length as discussed by the authors.
Abstract: Long-range surface plasmon polaritons (LRSPPs) are optical surface waves that propagate along a thin symmetric metal slab or stripe over an appreciable length (centimeters). Vigorous interest in LRSPPs has stimulated a large number of studies over three decades spanning a broad topical landscape. Naturally, a good segment of the literature covers fundamentals such as modal characteristics, excitation, and field enhancement. But a large portion also involves the LRSPP in diverse phenomena, including nonlinear interactions, molecular scattering, fluorescence, surface-enhanced Raman spectroscopy, transmission through opaque metal films and emission extraction, amplification and lasing, surface characterization, metal roughness and islandization, optical interconnects and integrated structures, gratings, thermo-, electro- and magneto-optics, and (bio)chemical sensing. Despite the breadth and depth of the research conducted to date, much remains to be uncovered, and the scope for future investigations is broad. We review the properties of the LRSPP, survey the literature involving this wave, and discuss the prospects for applications. Avenues for further work are suggested.

864 citations

Journal ArticleDOI
TL;DR: A graphene based perfect absorber is demonstrated and the properties of graphene wire medium and graphene fishnet metamaterials are investigated and both narrowband and broadband tunable absorbers are demonstrated.
Abstract: In this paper we present the efficient design of functional thin-film metamaterial devices with the effective surface conductivity approach. As an example, we demonstrate a graphene based perfect absorber. After formulating the requirements to the perfect absorber in terms of surface conductivity we investigate the properties of graphene wire medium and graphene fishnet metamaterials and demonstrate both narrowband and broadband tunable absorbers.

526 citations

Journal ArticleDOI
Abstract: Low bandgap and two-dimensional (2D)-conjugated copolymers based on benzo[1,2-b:4,5-b′]dithiophene with conjugated thiophene side chains (BDTT) and thieno[3,4-b]thiophene with electron-withdrawing substituents (TT) are attractive high efficiency polymer donor materials in polymer solar cells (PSCs). In this work, we introduced an alkylthio substituent on the thiophene side chain in the polymer and synthesized a new low bandgap 2D-conjugated polymer PBDTT-S-TT. The alkylthio substituent increased the hole mobility of the polymer to 4.08 × 10−3 cm2 V−1 s−1 and down-shifted the HOMO energy level of the polymer by 0.11 eV with absorption of the polymer film red-shifted slightly. The PSCs based on PBDTT-S-TT as a donor and [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) as an acceptor without solvent additive treatment demonstrated a high open-circuit voltage (Voc) of 0.84 V, leading to a high power conversion efficiency (PCE) of 8.42%, under the illumination of AM 1.5 G 100 mW cm−2. For comparison, the Voc and PCE of the devices based on the corresponding parent polymer PBDTT-TT with the device optimization of 3% DIO additive treatment are 0.77 V and 7.38%, respectively. The enhanced Voc value of 0.84 V for the PSC based on PBDTT-S-TT should be benefited from the down-shifted HOMO energy level of the polymer. The results indicate that the alkylthio substitution is an effective way to further improve the photovoltaic performance of the 2D-conjugated polymer donor materials in PSCs.

484 citations

Journal ArticleDOI
TL;DR: In this article, the crucial tactics employed to obtain high performance deep-blue emitters are presented, including polymers, dendrimers, small organic molecules, delayed fluorescent systems, and phosphorescent emitters.
Abstract: Blue organic light-emitting diodes (OLEDs) can play a critical role in the field of organic electroluminescence (EL). As the most important applications of OLEDs, both new generation full-color flat-panel displays and future energy-saving solid-state lighting sources require blue color EL to fulfill their functions properly. However, considerable challenges still exist in searching for highly efficient, color stable, and long-lifespan materials and devices that emit blue color, especially in the development of deep-blue emitters, which are indispensable for high-quality displays and lighting sources. Encouragingly, great progress has been made in the area of deep-blue OLEDs in recent years with continuous efforts made by scientists, who are responsible for the significant achievements in the field of OLEDs. Hence, in this review, the crucial tactics employed to obtain high performance deep-blue emitters are presented, including polymers, dendrimers, small organic molecules, delayed fluorescent systems, and phosphorescent emitters. Moreover, the future perspectives and ongoing challenges of this research frontier are also highlighted.

475 citations