Showing papers by "Alex K.-Y. Jen published in 2011"
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
TL;DR: In this paper, two lowband-gap conjugated polymers based on the polymerization between indacenodithiophene and 2,3-diphenylquinoxaline or phenanthrenequinoxalin were synthesized.
Abstract: Two new low-band-gap conjugated polymers based on the polymerization between indacenodithiophene and 2,3-diphenylquinoxaline or phenanthrenequinoxaline were synthesized. Due to the fused phenanthrenequinoxaline unit, the polymer (PIDT-phanQ) possesses better planarity than PIDT-diphQ, resulting in an improved hole mobility in organic field-effect transistors and power conversion efficiency in polymer solar cells.
319 citations
TL;DR: Small band-gap conjugated polymers based on monofluoro- and difluoro -substituted benzothiadiazole were developed and highly efficient polymer solar cells could be achieved for devices made from these polymers.
248 citations
TL;DR: To improve charge injection/extraction across the electrode/ organic semiconductor interface, several strategies have been developed, including modifying the electrode surface with self-assembled dipolar molecules to tune the energy level alignment at the semiconductor/electrode interface.
Abstract: Conjugated polymers are a novel class of solution-processable semiconducting materials with intriguing optoelectronic properties. [ 1 ] They have received great attention as active components in organic electronic devices such as organic photovoltaic cells (OPVs), organic light-emitting diodes (OLEDs), and organic fi eld-effect transistors (OFETs) due to their light weight, facile tuning of electronic properties through molecular engineering, and ease of processing. The performance and lifetime of conjugated polymer-based electronic devices are critically dependent on the bulk properties of the active materials and the interfacial properties of electrode/polymer contacts. [ 2–4 ] In these devices, the electrode(s) either inject charge into or extract charges from the organic semiconductor layer(s). Mismatch of the work functions between metal or metal oxide electrodes and molecular orbital energy levels of organic semiconductors can lead to high contact resistance, which decreases the charge injection and extraction effi ciency. Therefore, it is essential to minimize contact resistance at the electrode/organic semiconductor interface. To improve charge injection/extraction across the electrode/ organic semiconductor interface, several strategies have been developed. One is to tune the interfacial dipole across the electrode/semiconductor interface to reduce the injection/collection energy barrier. This can be achieved by modifying the electrode surface with self-assembled dipolar molecules to tune the energy level alignment at the semiconductor/electrode interface. [ 5–7 ] Alternatively, the introduction of a thin layer of polymer surfactant that contains polar side chains between the conjugate polymer/electrode interface can also be used to improve the interfacial properties. The polar side chains can provide not
233 citations
TL;DR: An effective in-device r(33) of 735 pm/V, which to the authors' knowledge is a record high, is demonstrated, which is ten times higher than the E-O coefficient achieved in thin film material.
Abstract: We design and fabricate a 320 nm slot for an electro-optic (E-O) polymer infiltrated silicon photonic crystal waveguide. Because of the large slot width, the poling efficiency of the infiltrated E-O polymer (AJCKL1/amorphous polycarbonate) is significantly improved. When coupled with the slow light effect from the silicon photonic crystal waveguide, an effective in-device r33 of 735 pm/V, which to our knowledge is a record high, is demonstrated, which is ten times higher than the E-O coefficient achieved in thin film material. Because of this ultrahigh E-O efficiency, the VπL of the device is only 0.44 V mm, which is to our knowledge the best result of all E-O polymer modulators.
141 citations
TL;DR: An overview of the development and utilization of organic electro-optic materials is presented with emphasis on the role played by quantum and statistical mechanical calculations in understanding critical structure/function relationships that have guided the improvement of such materials over the past two decades as discussed by the authors.
Abstract: An overview of the development and utilization of organic electro-optic materials is presented with emphasis on the role played by quantum and statistical mechanical calculations in understanding critical structure/function relationships that have guided the improvement of such materials over the past two decades. This review concentrates largely on three classes of organic electro-optic materials prepared by electric field poling of materials near their glass transition temperature: (1) chromophore/polymer composite materials, (2) dendrimers and polymers containing covalently incorporated chromophores, and (3) matrix-assisted-poling (MAP) materials where specific spatially anisotropic interactions enhance poling efficiency. In particular, the role of chromophore shape, restrictions on chromophore motion associated with covalent bonds, and lattice dimensionality effects are reviewed. The role of device design and auxiliary properties (optical loss, thermal stability, photochemical stability, processabilit...
131 citations
TL;DR: A ring-resonator modulator based on a silicon-polymer hybrid slot waveguide with a tunability of 12.7 pm/V at RF speeds and a bandwidth of 1 GHz, for optical wavelengths near 1550 nm is demonstrated.
Abstract: We demonstrate a ring-resonator modulator based on a silicon-polymer hybrid slot waveguide with a tunability of 127 pm/V at RF speeds and a bandwidth of 1 GHz, for optical wavelengths near 1550 nm Our slot waveguides were fabricated with 193 nm optical lithography, as opposed to the electron beam lithography used for previous results The tunability is comparable to some of the best ring-based modulators making use of the plasma dispersion effect The speed is likely limited only by resistance in the strip-loading section, and it should be possible to realize significant improvement with improved processing
130 citations
TL;DR: A series of low band-gap conjugated polymers (PDTC, PDTSi and PDTP) containing electron-rich C-, Si-, and N-bridged bithiophene and electron-deficient thienopyrroledione units were synthesized via Stille coupling polymerization as mentioned in this paper.
Abstract: A series of low band-gap conjugated polymers (PDTC, PDTSi and PDTP) containing electron-rich C-, Si-, and N-bridged bithiophene and electron-deficient thienopyrroledione units were synthesized viaStille coupling polymerization. All these polymers possess a low-lying energy level for the highest occupied molecular orbital (HOMO) (as low as −5.44 eV). As a result, photovoltaic devices derived from these polymers show high open circuit voltage (Voc as high as 0.91 V). These rigid polymers also possess respectable hole mobilities of 1.50 × 10−3, 6.0 × 10−4, and 3.9 × 10−4 cm2 V−1s−1 for PDTC, PDTSi, and PDTP, respectively. The combined high Voc and good hole mobility enable bulk hetero-junction photovoltaic cells to be fabricated with relatively high power conversion efficiency (PCE as high as 3.74% for the PDTC-based device).
118 citations
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
TL;DR: Two donor-acceptor polymers (P1 and P2) based on dithienobenzoquinoxaline (M1 and M2) as acceptor and indacenodithiophene as donor were synthesized via Stille polycond...
Abstract: Two donor–acceptor polymers (P1 and P2) based on dithienobenzoquinoxaline (M1) and dithienobenzopyridopyrazine (M2) as acceptor and indacenodithiophene as donor were synthesized via Stille polycond...
107 citations
TL;DR: A new type of benzobis(silolothiophene)-based low band gap copolymers PBSTBT and PBSTDTBT were developed via a facile synthetic method in high yield as discussed by the authors.
Abstract: A new type of benzobis(silolothiophene)-based low band gap copolymers PBSTBT and PBSTDTBT were developed via a facile synthetic method in high yield. The introduction of silicon atoms in the large fused rings provides new polymers with low HOMO levels and high hole mobilities up to 0.01 cm2 V−1 s−1. The results from preliminary characterization of bulk heterojuction solar cells showed PCE above 3.5% for both PBSTBT and PBSTDTBT.
TL;DR: In this article, two new semiconducting polymers based on indacenodithiophene and thiadiazolo[3,4-c]pyridine units were synthesized via Stille coupling polymerization.
Abstract: Two new semiconducting polymers based on indacenodithiophene and thiadiazolo[3,4-c]pyridine units were synthesized viaStille coupling polymerization. The polymers, PIDTPyT and PIDTDTPyT, exhibited main absorption bands in the range of 550–800 nm while their absorption maxima were located at around 700 nm in films. With two additional thiophene spacers, PIDTDTPyT showed a broader absorption band but a 20 nm blue-shifted maximum peak compared to that of PIDTPyT. Both of the polymers possess low bandgaps (∼1.6 eV) and deep energy levels for both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Organic field-effect transistors (OFETs) device measurements indicate that PIDTPyT and PIDTDTPyT have high hole carrier mobilities of 0.066 and 0.045 cm2 V−1s−1, respectively, with the on/off ratio on the order of 106. Bulk heterojunction photovoltaic devices consisting of the copolymers and PC71BM gave power conversion efficiencies (PCE) as high as 3.91% with broadband photo-response in the range of 300–800 nm. The relationships between the photovoltaic performance and film morphology, energy levels, hole mobilities are discussed.
TL;DR: Bulk hetero-junction devices based on using poly(3-hexylthiophene) and methano-PC( 61)BM as active layer exhibited better performance and thermal stability than those using the PC(61)BM analogue.
TL;DR: High conductivity and stochastic switching of anthracene-terminated phenylethynylthiolates within alkanethiolate monolayers, as well as in situ photochemical transformations, have been observed and distinguished with the scanning tunneling microscope (STM).
Abstract: The products of photoreactions of conjugated organic molecules may be allowed by selection rules but not observed in solution reactions because of unfavorable reaction geometries. We have used defect sites in self-assembled alkanethiolate monolayers on gold surfaces to direct geometrically unfavorable photochemical reactions between individual organic molecules. High conductivity and stochastic switching of anthracene-terminated phenylethynylthiolates within alkanethiolate monolayers, as well as in situ photochemical transformations, have been observed and distinguished with the scanning tunneling microscope (STM). Ultraviolet light absorbed during imaging increases the apparent heights of excited molecules in STM images, a direct manifestation of probing electronically excited states.
TL;DR: In this article, a spin-coating of a single component self-assembled monolayer (SAM) is used to simultaneously modify the bottom contact electrode and dielectric surfaces of organic thin-film transistors (OTFTs).
Abstract: An efficient process is developed by spin-coating a single-component, self-assembled monolayer (SAM) to simultaneously modify the bottom-contact electrode and dielectric surfaces of organic thin-film transistors (OTFTs). This efficient interface modification is achieved using n-alkyl phosphonic acid based SAMs to prime silver bottom-contacts and hafnium oxide (HfO{sub 2}) dielectrics in low-voltage OTFTs. Surface characterization using near edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and spectroscopic ellipsometry suggest this process yields structurally well-defined phosphonate SAMs on both metal and oxide surfaces. Rational selection of the alkyl length of the SAM leads to greatly enhanced performance for both n-channel (C60) and p-channel (pentacene) based OTFTs. Specifically, SAMs of n-octylphos-phonic acid (OPA) provide both low-contact resistance at the bottom-contact electrodes and excellent interfacial properties for compact semiconductor grain growth with high carrier mobilities. OTFTs based on OPA modifi ed silver electrode/HfO{sub 2} dielectric bottom-contact structures can be operated using < 3V with low contact resistance (down to 700 Ohm-cm), low subthreshold swing (as low as 75 mV dec{sup -1}), high on/off current ratios of 107, and charge carrier mobilities as high as 4.6 and 0.8 cm{sup 2} V{supmore » -1} s{sup -1}, for C60 and pentacene, respectively. These results demonstrate that this is a simple and efficient process for improving the performance of bottom-contact OTFTs.« less
TL;DR: In this article, a series of cross-linkable hole-transporting materials (X-HTMs) consisting of indacenodithiophene, bithiophen, and thiophene units bookended by two triarylamine groups have been designed and synthesized to investigate their suitability as new anode buffer layer for bulk heterojunction polymer solar cells (PSCs).
Abstract: A series of cross-linkable hole-transporting materials (X-HTMs) consisting of indacenodithiophene, bithiophene, and thiophene units bookended by two triarylamine groups have been designed and synthesized to investigate their suitability as new anode buffer layer for bulk heterojunction polymer solar cells (PSCs). These X-HTMs can be thermally cross-linked at temperature between 150 and 180 °C to form robust, solvent-resistant films for subsequent spin-coating of another upper layer. Energy levels of these cross-linked materials were measured by cyclic voltammetry, and the data suggest that these X-HTMs have desirable hole-collecting and electron-blocking abilities to function as an anode buffer layer for PSCs. In addition, by incorporating thiophene or fused ring units into the X-HTM backbone, it effectively improved the hole-carrier motilities. To further improve the conductivity and optical transparency for PSCs, the X-HTM films were p-doped with nitrosonium hexafluoroantimonate (NOSbF6). The doped X-HT...
TL;DR: In this paper, a novel [6,6]-phenyl-C61-butyric acid methyl styryl ester (PCBM-S) was synthesized and employed as an electron transporting interfacial layer for bulk heterojunction polymer solar cells with an inverted device configuration.
Abstract: A novel [6,6]-phenyl-C61-butyric acid methyl styryl ester (PCBM-S) was synthesized and employed as an electron transporting interfacial layer for bulk heterojunction polymer solar cells with an inverted device configuration. After the deposition of PCBM-S film from solution, the styryl groups of PCBM-S were polymerized by post-thermal treatment to form a robust film which is resistive to common organic solvents. This allows the solution processing of upper bulk heterojunction film without eroding the PCBM-S layer. Additionally, the PCBM-S was n-doped with decamethylcobaltocene (DMC) to increase the conductivity of the film, which resulted in a significantly improved power conversion efficiency from 1.24% to 2.33%. The improved device performance is due to the decrease of series resistance and improved electron extraction property of the n-doped PCBM-S film.
TL;DR: The utility of this process is demonstrated by fabricating self-organized and solution-processed low-voltage organic thin-film transistors enabled by patterned and spin-cast phosphonate SAM/metal oxide hybrid dielectrics.
Abstract: An efficient process is developed for modifying Si with self-assembled monolayers (SAMs) through in situ metal oxide surface activation and microcontact printing or spin-coating of phosphonic-acid-based molecules. The utility of this process is demonstrated by fabricating self-organized and solution-processed low-voltage organic thin-film transistors enabled by patterned and spin-cast phosphonate SAM/metal oxide hybrid dielectrics.
TL;DR: In this article, an externally initiated polymerization of 2-bromo-3-hexyl-5-iodothiophene was attempted from four aryl and thiophene based small molecule initiators functionalized with a phosphonate moiety.
Abstract: Externally initiated polymerization of 2-bromo-3-hexyl-5-iodothiophene was attempted from four aryl and thiophene based small molecule initiators functionalized with a phosphonate moiety. Initiated poly(3-hexylthiophene) product was obtained in various yields depending on the nature of the initiating molecule. Reaction intermediates for the oxidative addition and the ligand exchange steps were analyzed utilizing both experimental and theoretical methods. It was observed that an ortho substituent plays a crucial role in the outcome of the polymerization mechanism and that aryl based initiators are generally more stable than thiophene based initiators. Density functional theory (DFT) calculations revealed the importance of the steric effects on the success of the externally initiated chain growth polymerization mechanism.
TL;DR: A series of phenyltetraene-based nonlinear optical (NLO) chromophores with the same donor and acceptor groups, but different tetraene bridges that are partly connected by various sizes of aliphatic rings, have been synthesized and systematically investigated as mentioned in this paper.
Abstract: A series of phenyltetraene-based nonlinear optical (NLO) chromophores 1a–c with the same donor and acceptor groups, but different tetraene bridges that are partly connected by various sizes of aliphatic rings, have been synthesized and systematically investigated. The interposed conjugated tetraene segments in three chromophores studied are based on isophorone, (1S)-(−)-verbenone, and 3,4,4-trimethyl-2-cyclopentenone, respectively. This kind of structural alteration has significant effect on the intrinsic electronic structures and physical properties of these highly polarizable chromophores as revealed by a variety of characterization techniques. The introduction of the verbenone- and trimethylcyclopentenone-based tetraene bridges could significantly improve the glass-forming ability of chromophores 1b and 1c in comparison with the highly crystalline characteristics of isophorone-based chromophores 1a. More importantly, chromophores 1a–c exhibited distinct optical features in absorption band shape, solvatochromic behavior, as well as energy band gap from the UV-vis-NIR absorption measurements. Quantum mechanical calculations using density functional theory (DFT) were also used to evaluate second-order NLO properties of these chromophores. The electro-optic (EO) coefficients of 1a–c in poled polymers with the 10 wt% chromophore content showed an apparent decrease from 78 pm V−1 for 1a to 42 pm V−1 for 1c. This decrease is attributed to the gradual decrease of the molecular hyperpolarizability (β) of the chromophores which is associated with the progressive cyanine-like electronic structure from the isophorone-based 1a to the cyclopentenone-based 1cchromophore.
TL;DR: In this article, an electro-optic polymer-clad silicon slot waveguide was used for a Mach-Zehnder interferometer (MZI) modulator with a half-wave voltage of only 0.69 V and a bandwidth of 500 MHz.
Abstract: Lowering the operating voltage of electro-optic modulators is desirable for a variety of applications, most notably in analog photonics and digital data communication. In particular for digital systems such as CPUs, it is desirable to develop modulators that are both temperature-insensitive and compatible with typically sub-2 V CMOS electronics; however, drive voltages in silicon-based Mach-Zehnder interferometers (MZIs) currently exceed 1.8 V. Here, we show an MZI modulator based on an electro-optic polymer-clad silicon slot waveguide, with a halfwave voltage of only 0.69 V (corresponding to a 0.62 V(·)cm modulation figure of merit), and a bandwidth of 500 MHz. We also show that there are paths to significantly improve both the bandwidth and drive voltage.
TL;DR: In this article, the role of surface hydroxyl groups on TiO2(B) nanowires was investigated via various surface modifications, and it was found that a higher density of surface hyroxyl group will constantly enhance the chemiresistive response of the nanowire to the nitro-explosives vapors.
Abstract: Thin films of TiO2(B) nanowires are known to have sensitive and fast response to vapors of nitro-explosives under ambient conditions. The sensing response is believed to be affected by the humidity of ambient air that changes the density of hydroxyl groups on the TiO2(B) surfaces. To verify this mechanism, the role of surface hydroxyl groups on TiO2(B) nanowires was investigated via various surface modifications. It was found that a higher density of surface hydroxyl groups will constantly enhance the chemiresistive response of TiO2(B) nanowires to the nitro-explosives vapors. These surface hydroxyl groups serve as a pathway for effective charge transfer between the nitro groups on the explosive molecules and the TiO2(B). The evidence of charge transfer complex formation between nitro groups and titanium dioxide is also confirmed by Fourier transform infrared spectroscopy.
TL;DR: In this article, a bulk-heterojunction polymer solar cells based on two indacenodithiophene-containing low bandgap, high mobility polymers in both conventional and inverted device configurations are demonstrated.
TL;DR: The top surface (the film/air interface) is enriched in P3HT compared to the bulk, regardless of substrate or annealing conditions, indicating that changes in device performance due to substrate modification treatments should be attributed to the buried substrate/film interface and the bulk of the film rather than the exposed film/ air interface.
Abstract: We study the top surface composition of blends of the conjugated polymer regioregular poly-3-hexylthiophene (P3HT) with the fullerene (6,6)-phenyl-C61-butyric acid methyl ester (PCBM), an important model system for organic photovoltaics (OPVs), using near-edge X-ray absorption fine structure spectroscopy (NEXAFS). We compare the ratio of P3HT to PCBM near the air/film interface that results from preparing blend films on two sets of substrates: (1) poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) coated indium tin oxide (ITO) as is commonly used in conventional OPV structures and (2) ZnO substrates that are either unmodified or modified with a C60-like self-assembled monolayer, similar to those that have been recently reported in inverted OPV structures. We find that the top surface (the film/air interface) is enriched in P3HT compared to the bulk, regardless of substrate or annealing conditions, indicating that changes in device performance due to substrate modification treatments shoul...
TL;DR: In this paper, a short polymeric directional coupler switches based on hybrid EO polymer/sol-gel silica waveguides were used to achieve an in-device EO coefficient of 160 pm/V at 1550 nm.
Abstract: The highest electro-optic (EO) coefficient to date is achieved in short polymeric directional coupler switches based on hybrid EO polymer/sol-gel silica waveguides. Optimized poling conditions in such waveguides give a highest in-device EO coefficient of 160 pm/V at 1550 nm using highly efficient and photostable guest–host EO polymer SEO100. Adiabatic waveguide transitions from the passive sol-gel core to active EO polymer cores surrounding the sol-gel core are shown using EO polymer cores with a coplanar tapered structure. Switching voltages of 8.4 and 10.5 V are achieved for electrodes that are 2.1 and 1.5 mm long, respectively, which are half those of EO switches containing the chromophore AJLS102.
TL;DR: It is explained that the best material for the slab waveguide is an inorganic material because of the low RF permittivity combined with the high electro-optic coefficient.
Abstract: This paper provides a detailed analysis of electric field sensing using a slab-coupled optical fiber sensor (SCOS). This analysis explains that the best material for the slab waveguide is an inorganic material because of the low RF permittivity combined with the high electro-optic coefficient. The paper also describes the fabrication and testing of a SCOS using an AJL chromophore in amorphous polycarbonate. The high uniform polymer slab waveguide is fabricated using a hot embossing process to create a slab with a thickness of 50 μm. The fabricated polymer SCOS was characterized to have a resonance slope of ΔP/Δλ=6.83E5 W/m and a resonance shift of Δλ/E=1.47E−16 m2/V.
TL;DR: In this paper, the self-assembling properties of two rationally designed discotic π-conjugated hexaazatrinaphthylene (HATNA) molecules have been studied.
Abstract: The self-assembling properties of two rationally designed discotic π-conjugated hexaazatrinaphthylene (HATNA) molecules have been studied. In appropriate solvent systems, both ester-dodecyl-substituted and amide-dodecyl-substituted HATNAs self-assembled into nanowires and formed organogels. These nanowires could be easily transferred onto solid supports through spin casting for morphological study. In addition to the solution-based self-assembly method, solvent-vapor annealing (SVA) was explored as an alternative way to control the organization of supramolecular nanowires on surfaces. It was found that amorphous thin film of HATNA molecules transformed gradually into nanowire structures through a nucleation and growth mechanism during the SVA process. Several parameters including the preordering of molecules in the original thin film, choice of solvent vapors, annealing times, and surface properties were tuned to create different supramolecular organizations. Under particular conditions, aligned nanowires with preferential direction can be achieved.
TL;DR: A spatial light modulator based on a Fabry-Perot interferometer configuration has been fabricated and tested and measurement results demonstrate the modulation of multiple pixels operating simultaneously at frequencies ranging from 300 kHz to 800 kHz which is significantly faster than SLMs based on liquid crystal and digital micromirror device technology.
Abstract: A spatial light modulator (SLM) based on a Fabry-Perot interferometer configuration has been fabricated and tested. The Fabry-Perot spacer layer is a thin film of the SEO100 electro-optic polymer which serves as the nonlinear medium. Measurement results demonstrate the modulation of multiple pixels operating simultaneously at frequencies ranging from 300 kHz to 800 kHz which is significantly faster than SLMs based on liquid crystal and digital micromirror device technology. An average modulation contrast of 50% for all pixels is achieved with a drive voltage of 70 Vrms at 100 kHz. Microwave speeds and CMOS compatibility are feasible with improved transmission line and cavity design.