Transparent conductors for Mid-infrared liquid crystal spatial light modulators

Micallef, Fabian; Shrestha, Pawan Kumar; Chu, Daping; McEwan, Ken; Rughoobur, Girish; Carey, Tian; Coburn, Nigel J.; Torrisi, Felice; Txoperena, Oihana; Zurutuza, Amaia

doi:10.1016/j.tsf.2018.05.037

Cited by 13 publications

(3 citation statements)

References 35 publications

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“…Figure 5b shows that our TOS-doped graphene displays superior performance at telecommunication wavelength (1550 nm) as compared to other conventional transparent conducting films, including indium tin oxide (ITO), zinc-doped indium oxide (IZO), zirconiumdoped indium oxide (IO:Zr), hydrogen-doped indium oxide (IO:H), zinc oxide (ZnO), and aluminum-doped zinc oxide (AZO). [43][44][45][46][47] In general, traditional transparent conductors suffer from a trade-off between transmittance and sheet resistance. In contrast, our CVD TOS/Gr and exfoliated TOS/3L-WSe2/Gr samples provide exceptionally higher transmittance while maintaining remarkably low sheet resistance, >99% transmittance at 197 /□ and 97.7% at 48 /□, respectively.…”

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confidence: 99%

High carrier mobility in graphene doped using a monolayer of tungsten oxyselenide

et al. 2021

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Highly doped graphene holds promise for next-generation electronic and photonic devices.However, chemical doping cannot be precisely controlled, and introduces external disorder that significantly diminishes the carrier mobility and therefore the graphene conductivity. Here, we show that monolayer tungsten oxyselenide (TOS) created by oxidation of WSe2 acts as an efficient and low-disorder hole-dopant for graphene. When the TOS is directly in contact with graphene, the induced hole density is 3 × 10 13 cm -2 , and the room-temperature mobility is 2,000 cm 2 /V•s, far exceeding that of chemically-doped graphene. Inserting WSe2 layers between the TOS and graphene tunes the induced hole density as well as reduces charge disorder such that the mobility exceeds 20,000 cm 2 /V•s and reaches the limit set by acoustic phonon scattering, resulting in sheet resistance below 50 /□. An electrostatic model based on work-function mismatch accurately describes the tuning of the carrier density with WSe2 interlayer thickness. These films show unparalleled performance as transparent conductors at telecommunication wavelengths, as shown by measurements of transmittance in thin films and insertion loss in photonic ring resonators. This work opens up new avenues in optoelectronics incorporating two-dimensional heterostructures including infrared transparent conductors, electro-phase modulators, and various junction devices.

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confidence: 99%

High carrier mobility in graphene doped using a monolayer of tungsten oxyselenide

et al. 2021

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“…Solution-processing techniques such as electrochemical exfoliation [10][11][12] and liquid-phase exfoliation (LPE), including shear mixing [13], microfluidization [3,6] and ultrasonication [14][15][16] have enabled large-scale production of graphene and other E2D inks [2,3] with the required different electronic properties. Many electronic [1,17,18], optoelectronic [19,20], and photonic [21][22][23] devices have been demonstrated via several printing methods such as inkjet printing [3,4,24], screen printing [6,25], flexographic printing [26], gravure printing [7], and spray coating [27,28]. Above all, drop-on-demand (DoD) inkjet printing unleashed the full potential of E2D inks, combining advantages such as versatility to print on wide range of substrates (e.g.…”

Section: Introductionmentioning

confidence: 99%

Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials

et al. 2021

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Printed electronics has emerged as a pathway for large scale, flexible, and wearable devices enabled by graphene and two-dimensional (2D) materials. Solution processing of graphite and layered materials demonstrated mass production of inks allowing techniques such as inkjet printing to be used for device fabrication. However, the complexity of the ink formulations and the polycrystalline nature of the thin films, together with the metal, semimetal, and semiconducting behaviour of different 2D materials, have impeded the investigation of charge transport in inkjet printed 2D material devices. Here we unveil the charge transport mechanisms of surfactant-and solvent-free inkjet-printed thin-film devices of representative few-layer graphene (semi-metal), molybdenum disulfide (MoS2, semiconductor) and titanium carbide MXene (Ti3C2, metal) by investigating the temperature (T ), gate and magnetic field dependencies of their electrical conductivity. We find that charge transport in printed few-layer MXene and MoS2 devices is dominated by the intrinsic transport mechanism of the constituent flakes: MXene devices exhibit a weakly-localized 2D metallic behavior at any T , whereas MoS2 devices behave as insulators with a crossover from 3D-Mott variable-range hopping at low T to nearest-neighbor hopping around at ∼ 200 K. The charge transport in printed few-layer graphene devices is dominated by the transport mechanism between different flakes, which exhibit 3D-Mott variable range hopping conduction at any T . These findings reveal and finally establish the fundamental mechanisms responsible for charge transport in inkjet-printed devices with 2D materials, paving the way for a reliable design of high performance printed electronics.

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“…Materials are also available at comparable performance to ITO (Figure 19a), yet at still higher cost and mostly not having been scaled up to sizes and the reproducibility of industrial standard (Figure 19b). The main problem with Other applications of ITO-free LC applications with carbon-based electrodes that have been reported include cholesteric multi-domain structures for energy-saving smart windows [174], mid IR spatial light modulators [175], micro-lens arrays [176], and tuneable scattering devices [177].…”

Section: Discussion and Outlookmentioning

confidence: 99%

Carbon Allotropes as ITO Electrode Replacement Materials in Liquid Crystal Devices

Dierking

2020

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Indium tin oxide (ITO)-free optoelectronic devices have been discussed for a number of years in the light of a possible indium shortage as demand rises. In particular, this is due to the largely increased number of flat panel displays and especially liquid crystal displays (LCDs) being produced for home entertainment TV and mobile technologies. While a shortage of primary indium seems far on the horizon, nevertheless, recycling has become an important issue, as has the development of ITO-free electrode materials, especially for flexible liquid crystal devices. The main contenders for new electrode technologies are discussed with an emphasis placed on carbon-based materials for LCDs, including composite approaches. At present, these already fulfil the technical specifications demanded from ITO with respect to transmittance and sheet resistance, albeit not in relation to cost and large-scale production. Advantages and disadvantages of ITO-free technologies are discussed, with application examples given. An outlook into the future suggests no immediate transition to carbon-based electrodes in the area of LCDs, while this may change in the future once flexible displays and environmentally friendly smart window solutions or energy harvesting building coverings become available.

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Transparent conductors for Mid-infrared liquid crystal spatial light modulators

Cited by 13 publications

References 35 publications

High carrier mobility in graphene doped using a monolayer of tungsten oxyselenide

High carrier mobility in graphene doped using a monolayer of tungsten oxyselenide

Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials

Carbon Allotropes as ITO Electrode Replacement Materials in Liquid Crystal Devices

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