Organic electro-optic modulator using transparent conducting oxides as electrodes

Xu, Guoyang; Liu, Zhifu; Ma, Jing; Liu, Boyang; Ho, Seng Tiong; Wang, Lian; Zhu, Ping; Marks, Tobin J.; Luo, Jingdong; Jen, Alex K.‐Y.

doi:10.1364/opex.13.007380

Cited by 66 publications

(27 citation statements)

References 15 publications

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“…[ ); thin films can be deposited via a proven room-temperature growth process. [24,25] In this work, In 2 O 3 thin films are deposited at room temperature by ion-assisted deposition (IAD), a scalable process combining two active ion beams (primary ion beam and assisted ion beam) to simultaneously manipulate film growth, oxidation, and crystallization. Besides the background O 2 partial pressure, additional O 2 can be integrated into the assisted beam to produce active oxygen ions.…”

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confidence: 99%

Flexible Inorganic/Organic Hybrid Thin‐Film Transistors Using All‐Transparent Component Materials

et al. 2007

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Mechanical flexibility, optical clarity, light weight, and low production cost are highly desirable thin-film transistor (TFT) characteristics. Hence, scalable/benign large-area fabrication processes for such devices are the object of rapidly growing interest with the ultimate goal of producing switching devices for portable, "invisible" electronics. [1][2][3][4] Since the first entirely transparent TFT was reported in 2003, [5] extensive academic and industrial efforts have focused on enhancing the operating performance of such devices. [6][7][8][9][10][11][12] This has included sustained efforts to achieve transparent TFT flexibility or bendability on plastic substrates [3,[13][14][15][16] recognizing: (1) the low maximum working temperatures (T g : 80-150°C) and high thermal expansion coefficients of typical low-cost, optically clear plastics; (2) the limited high-quality transparent semiconductor and dielectric candidate materials which can be grown at low temperatures; (3) the lack of appropriate lowtemperature thin-film fabrication technologies to deposit such materials. Therefore, the development of optimum TFT component materials and low-temperature device fabrication processes is of high priority. In this contribution, we report a new class of inorganic/organic hybrid TFTs which are first fabricated and optimized on doped silicon gates/substrates, and then incorporated into transparent, flexible TFTs on PET substrates. These devices have good visible transparency, mechanical flexibility, and current modulation characteristics. Note that the entire TFT fabrication process is carried out near room temperature and is scalable, thus providing an attractive pathway for future large-area plastic electronics. Essential parameters describing TFT device performance are the field-effect mobility (l FE ), I on /I off modulation ratio, threshold voltage (V T ), subthreshold voltage swing (S), and operating voltage. [17,18] For TFT applications such as switching devices, a sharp step-like current-voltage response is desired.In practical TFTs, the off-state current (I off ) flowing through the device when V GS < V T (V GS is the bias applied between gate and source electrodes) must be minimal; on the other hand, the on-state current (I on ) is intrinsically limited by the channel mobility and must be maximized to realize optimum current modulation. Modulation/switching occurs within the range of applied V GS when V DS (applied bias between the drain and source electrodes) is fixed at a certain value, and is characterized by the subthreshold voltage swing. Thus, efficient TFT response demands large field-effect mobilities in the semiconducting channel layer and excellent electrical insulating properties in the proximate dielectric layer. In addition, for transparent and flexible TFTs, optical transparency of the materials set and compatibility with mechanically compliant plastics must be achieved. Among potential semiconductor candidates for transparent and flexible TFTs, metal oxide semiconductors are arguably some of...

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confidence: 99%

Flexible Inorganic/Organic Hybrid Thin‐Film Transistors Using All‐Transparent Component Materials

et al. 2007

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“…[3,4] For optical circuits, EO polymers can be easily integrated with stripline-or ring-structured waveguides made of sol-gels, [5] low-loss fluorinated polymers, [6] silicon slots, [7] conducting oxides, [8] and photonic crystals. [9] Recently, EO polymers have also been utilized for the generation/detection of a gap-free pulsed THz system with a bandwidth up to ca.…”

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confidence: 99%

“…In 1a-c, the skeleton "donor-(p-bridge)-acceptor" chromophore is structurally the same as that of AJL8, which is one of the standardized chromophores for EO devices. [8,10] AJC146…”

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confidence: 99%

Ultralarge and Thermally Stable Electro‐optic Activities from Diels–Alder Crosslinkable Polymers Containing Binary Chromophore Systems

et al. 2006

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Poled electro-optic (EO) polymers have enabled many advances in the exploration of high-speed and broadband information technologies.[1] Polymer based EO devices have been demonstrated to have large bandwidths (over 110 GHz), low driving voltages, and sustain their performance in a flexible form [2] or under extreme environmental conditions. [3,4] For optical circuits, EO polymers can be easily integrated with stripline-or ring-structured waveguides made of sol-gels, [5] low-loss fluorinated polymers, [6] silicon slots, [7] conducting oxides, [8] and photonic crystals. [9] Recently, EO polymers have also been utilized for the generation/detection of a gap-free pulsed THz system with a bandwidth up to ca. 12 THz.[10]Large numbers of discrete photonic components need to be inserted into integrated systems of telecommunication and silicon microphotonics, especially where an extreme amount of data is required to travel in a very small space.[11] Therein lies the great challenge for polymer-based EO technologies: to have thermally stable EO coefficients (r 33 ) of around 500 pm V -1 at wavelengths of 1.31 or 1.55 lm.[11b]Currently, the most commonly used materials for polymeric EO devices are based on poled polymers with r 33 values around 50-80 pm V -1 at wavelengths of 1.31 or 1.55 lm. In these materials, dipolar nonlinear optical (NLO) chromophores have been doped or incorporated at a level of ca. 20-25 wt % to reach their maximum r 33 values. [5][6][7][8][9][10] Beyond such a moderate loading of chromophores, strong intermolecular electrostatic interactions severely limit the poling-induced polar order and cause phase-separation problems between chromophores and polymers.To further improve EO activity, research efforts have focused on developing shape-engineered chromophores with high molecular optical nonlinearities (lb), [12] where lb is a product of first hyperpolarizability and the dipole moment of the NLO chromophore, and increasing order within the matrices by controlling the nanoscale architecture of macromolecules. [13] In our recent study we have demonstrated, using Diels-Alder (DA) "click chemistry" to post-functionalize NLO chromophores onto polymers, that high chromophore loading levels (up to 35 wt %) and large r 33 values (up to 110 pm V -1 ) could be achieved in in situ generated side-chain dendronized NLO polymers with non-reacted chromophores as guest dopants. [14] This opens a new avenue to explore optimal host-guest combinations and to develop an efficient way to control lattice hardening in these hybrid polymers. The ultimate goal is to simultaneously achieve very large EO activity, good thermal stability, high optical transparency, and excellent mechanical properties within the same material via molecular design and facile processing. In this paper, we report a novel method to disperse a highly efficient secondary chromophore into in situ crosslinked NLO polymer networks, leading to both enhanced EO activity (> 260 pm V -1 at 1.31 lm) and alignment stability at 85°C. In photorefractive (PR) po...

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“…We have reported initial fabrication and characterization results for a TC-based organic EO modulator [24]. This initial work was not designed for high-speed operation, but demonstrated the low voltage achieved.…”

Section: Experimental Realization Of a Tc-based Organic Eo Modulator mentioning

confidence: 99%

Organic Electro‐Optic Modulators with Substantially Enhanced Performance Based on Transparent Electrodes

Yi¹,

Ho²,

Marks

2010

Transparent Electronics

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This chapter describes the application of transparent electrodes to enhance the performance of electro-optic (EO) modulators. Transparent electrodes are typically made from transparent conducting oxides (TCOs). They are electrically conductive while having significantly lower optical absorption loss compared with metals. Their optical refractive indices are typically around n TC ¼ 1.6-2.0, which makes them compatible for use as optical waveguiding materials in organic EO modulators. In this chapter, we show that with use of transparent electrodes as 'bridge electrodes' together with a proper design of a metallic transmission line, high-speed organic EO modulators with substantially lower switching voltages can be realized. In this chapter, we describe in detail the design, fabrication, and characterization of an organic EO modulator based on transparent electrodes. We show that transparent-conductor (TC)-based EO modulator structures can be used to reduce modulator switching voltages by over 5-15x compared with organic modulators based on conventional organic EO modulator structures, while still achieving broad modulation bandwidths of 10-100 GHz, depending on the properties of the transparent conducting materials. The TC-based EO modulator structures are particularly advantageous when Transparent Electronics: From Synthesis to Applications Edited by Antonio Facchetti and Tobin J. Marks

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Organic electro-optic modulator using transparent conducting oxides as electrodes

Cited by 66 publications

References 15 publications

Flexible Inorganic/Organic Hybrid Thin‐Film Transistors Using All‐Transparent Component Materials

Flexible Inorganic/Organic Hybrid Thin‐Film Transistors Using All‐Transparent Component Materials

Ultralarge and Thermally Stable Electro‐optic Activities from Diels–Alder Crosslinkable Polymers Containing Binary Chromophore Systems

Organic Electro‐Optic Modulators with Substantially Enhanced Performance Based on Transparent Electrodes

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