Large-area functionalized CVD graphene for work function matched transparent electrodes

Bointon, Thomas H.; Jones, Gareth J. F.; Sanctis, Adolfo De; Pearce, Ruth; Craciun, Monica F.; Russo, Saverio

doi:10.1038/srep16464

Cited by 50 publications

(59 citation statements)

References 24 publications

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“…Contrary to ACEL devices employing alternative electrode materials, the use of FeCl 3 -FLG transparent electrodes does not show any measurable gradient of the intensity of the emitted light in flat panels 4cm long and 0.8 mm wide, owing to the low sheet resistance of FeCl 3 -FLG. 16 This finding is in stark contrast to the experimentally measured 70% reduction in the intensity of the emitted light measured in ACEL devices embedding FLG electrodes. Finally, we demonstrate the performance of this outstanding transparent electrode in flexible and foldable lighting devices fabricated on polyethylene terephthalate (PET).…”

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confidence: 70%

“…In this work we present the use of the outstanding transparent conductor FeCl 3 intercalated few-layer graphene (FeCl 3 -FLG) 5,15,16 for highly uniform, flexible and foldable ACEL devices.…”

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confidence: 99%

“…16 It is highly stable against 100% humidity and temperature up to 150 o C, 17 and was shown to be a promising material for work function matched transparent electrodes in photovoltaic and organic light emitting devices 5,16 and photodetectors. 18 We compare the performance of this emerging material against the widely-used conductive polymer PEDOT:PSS and other graphene electrodes such as single-layer graphene (SLG) and FLG.…”

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confidence: 99%

“…In both cases, the emission spectra have a very similar shape stemming from the flat optical transmittance of FeCl 3 -FLG and pristine FLG in the emission range of the phosphor layer. 15,16 Hence, we fit the spectra of each ACEL device with the superposition of the four known Gaussian emission bands (λ =438nm, 464nm, 497 and 525nm) corresponding to the intraband transitions originating from sulphur vacancy states and a variety of surface states. 20 Broadening of these peaks is mainly determined by variations in the size 21 and crystalline phase 3 of phosphor particles.…”

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confidence: 99%

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Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes

Alonso

Karkera

Jones

et al. 2016

ACS Appl. Mater. Interfaces

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Alternating current electroluminescent technology allows the fabrication of large area, flat and flexible lights. Presently the maximum size of a continuous panel is limited by the high resistivity of available transparent electrode materials causing a visible gradient of brightness.Here, we demonstrate that the use of the best known transparent conductor FeCl 3 -intercalated few-layer graphene boosts the brightness of electroluminescent devices by 49% compared to pristine graphene. Intensity gradients observed for high aspect ratio devices are undetectable when using these highly conductive electrodes. Flat lights on polymer substrates are found to be resilient to repeated and flexural strains. * To whom correspondence should be addressed 1 arXiv:1606.05482v1 [cond-mat.mtrl-sci] Jun 2016Displays and screens are some of the most important devices within the field of optoelectronics.Large-area displays are ubiquitous in advertising, ambient lighting, television, computer screens and almost every device with an interface for its control. Current research is focused on making these devices suitable for the next generation of flexible and foldable optoelectronics. In particular, foldable displays and lighting systems would allow expandable screens for smart phones and electronic paper, wearable optoelectronics, rollable or collapsible wallpaper lights, and biocompatible light sources for medical devices. To date, alternating current electroluminescent (ACEL) technology uniquely enables the realization of flat, large-area (≈ 1m 2 ) and flexible light sources. 1 ACEL devices have good contrast and uniform brightness. They can display images with high resolution when employing nano-patterned electrodes and they can withstand mechanical shocks as well as a wide range of temperatures. 2,3 Presently, the maximum size of ACEL lighting panels is still limited to less than a square meter under practical operational conditions. This is due to the visible gradient of brightness which develops across a panel induced by the high sheet resistance (typically larger than 100Ω/2) of the transparent electrode materials. 4,5 Highly resistive electrodes also require a high operational voltage and frequency, leading to increased power consumption and accelerated device degradation. 1,5 Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a transparent and conductive polymer widely used by the printed electronics industry owing to its high mechanical flexibility. However, PEDOT:PSS has a high sheet resistance of 850Ω/2 for an optical transparency of 90%, 6-8 an unwanted blue tinge 8 and limited environmental stability. 6-8 When exposed to relative humidity of just 40%, the uptake of water by the hygroscopic PSS leads to the development of shear lips when the films are deformed, greatly increasing the sheet resistance. 7 Moreover, the absorption of water combined with the acidity of PSS is a well-known cause of degradation in device components. 9,10 Atomically thin conductors such as graphene possess many attrac...

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Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes

Alonso

Karkera

Jones

et al. 2016

ACS Appl. Mater. Interfaces

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“…12 This metric also provides better insight into the doping conditions in the graphene sheets, by correlating the charge carrier concentration calculated from the PosG value with optical images of the FeCl 3 -FLG sample it can be seen how the doping, and hence intercalation, varies with the thickness of each flake as well as the density of flakes in the film.…”

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confidence: 99%

Wafer scale FeCl3 intercalated graphene electrodes for photovoltaic applications

Walsh

Murphy

Jones

et al. 2018

Photonics for Solar Energy Systems VII

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The alteration of graphene's electrical properties through chemical functionalization is a necessary process in order for graphene to fulfill its potential as a transparent conducting electrode. In this work, we present a method for the transfer and intercalation of large area (wafer scale) graphene samples to produce highly doped FeCl 3 intercalated Few Layer Graphene (FeCl 3 -FLG). Given its excellent flexibility, transmission, and a sheet resistance, comparable to that of Indium Tin Oxide, FeCl 3 -FLG has potential to replace alternative flexible transparent electrodes as well as compete with rigid transparent electrodes. We assess the effect of functionalization temperature on the degree of intercalation in the large area samples and comparing results to that of 1 cm 2 FeCl 3 -FLG samples. Raman spectroscopy is then used to characterize samples, where we introduce a new figure of merit ( PosG ) by which to assess the degree of intercalation in a sample. This is an average G peak position, weighted by the areas of the constituent peaks, which can then be used to map the charge carrier concentration of the sample. The inhomogeneity of the graphene grown by chemical vapor deposition is found to be one of the limiting factors in producing large area, high quality FeCl 3 -FLG.

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Highly Conductive and Transparent Large‐Area Bilayer Graphene Realized by MoCl₅ Intercalation

et al. 2017

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Bilayer graphene (BLG) comprises a 2D nanospace sandwiched by two parallel graphene sheets that can be used to intercalate molecules or ions for attaining novel functionalities. However, intercalation is mostly demonstrated with small, exfoliated graphene flakes. This study demonstrates intercalation of molybdenum chloride (MoCl ) into a large-area, uniform BLG sheet, which is grown by chemical vapor deposition (CVD). This study reveals that the degree of MoCl intercalation strongly depends on the stacking order of the graphene; twist-stacked graphene shows a much higher degree of intercalation than AB-stacked. Density functional theory calculations suggest that weak interlayer coupling in the twist-stacked graphene contributes to the effective intercalation. By selectively synthesizing twist-rich BLG films through control of the CVD conditions, low sheet resistance (83 Ω ▫ ) is realized after MoCl intercalation, while maintaining high optical transmittance (≈95%). The low sheet resistance state is relatively stable in air for more than three months. Furthermore, the intercalated BLG film is applied to organic solar cells, realizing a high power conversion efficiency.

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Large-area functionalized CVD graphene for work function matched transparent electrodes

Cited by 50 publications

References 24 publications

Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes

Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes

Wafer scale FeCl3 intercalated graphene electrodes for photovoltaic applications

Highly Conductive and Transparent Large‐Area Bilayer Graphene Realized by MoCl₅ Intercalation

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Large-area functionalized CVD graphene for work function matched transparent electrodes

Cited by 50 publications

References 24 publications

Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes

Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes

Wafer scale FeCl3 intercalated graphene electrodes for photovoltaic applications

Highly Conductive and Transparent Large‐Area Bilayer Graphene Realized by MoCl5 Intercalation

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Highly Conductive and Transparent Large‐Area Bilayer Graphene Realized by MoCl₅ Intercalation