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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