Multifunctional oxides for integrated manufacturing of efficient graphene electrodes for organic electronics

Abstract

Using multi-functional oxide films, we report on the development of an integration strategy for scalable manufacturing of graphene-based transparent conducting electrodes (TCEs) for organic electronics. A number of fundamental and process challenges exists for efficient graphene-based TCEs, in particular, environmentally and thermally stable doping, interfacial band engineering for efficient charge injection/extraction, effective wetting, and process compatibility including masking and patterning. Here, we show that all of these challenges can be effectively addressed at once by coating graphene with a thin (>10 nm) metal oxide (MoO3 or WO3) layer. We demonstrate graphene electrode patterning without the need for conventional lithography and thereby achieve organic light emitting diodes with efficiencies exceeding those of standard indium tin oxide reference devices.

Engineering high charge transfer n-doping of graphene electrodes and its application to organic electronics

“…Alkali metals are well known for their efficient electron transfer in organic semiconductors and their compounds are typically used for ease of material handling and process control. The slight increase in sheet resistance at lower pressures (around 10 -6 mbar) is attributed to a diminishing unintentional p-doping due to air exposure [7][8][9] and PMMA residue from the graphene transfer process. We show that the graphene ndoping thereby achieved is significantly higher than for recently reported polymer films containing aliphatic amine groups, 26 polyethylenimine ethoxylated (PEIE), 26,27,32 and using photoemission spectroscopy we develop a detailed understanding of the doping mechanism and energy level alignment.…”

“…[1][2][3][4][5][6][7][8] Most of these applications require low sheet resistances and detailed band engineering to optimize charge injection/extraction. [7][8][9] This is best achieved by charge transfer [7][8][9] or field-effect/electrostatic doping approaches, [10][11][12] as substitutional doping and other methods based on covalent bonding degrade the graphitic layer quality. [7][8][9] This is best achieved by charge transfer [7][8][9] or field-effect/electrostatic doping approaches, [10][11][12] as substitutional doping and other methods based on covalent bonding degrade the graphitic layer quality.…”

Atomic layer deposited oxide films as protective interface layers for integrated graphene transfer

“…It is conceivable that dopant materials could be incorporated at the graphene-oxide interface to strongly dope the graphene for applications requiring low sheet resistance such as organic light emitting diodes [75]. The oxide support may also be exploited as a hard mask [76] in devices avoiding the use of polymers and other organic solvents that can leave undesirable carbon residues on the graphene surface.…”

State-of-the-Art Electronic Devices Based on Graphene

“…Touch screens require graphene-woven fabric to develop smart self-sensing elements based on piezo resistors directly transferred onto flexible substrates such as poly(dimethylsiloxane) (PDMS) [70]. Organic light-emitting diodes (OLEDs) are benefiting significantly from graphene-based transparent conducting electrodes (TCEs) where thin films of semiconducting metal oxides such as MoO 3 or WO 3 cover graphene [71]. The oxide coating provides effective graphene doping, ideal alignment of the transport levels at the graphene interface, effective wetting and graphene protection during etching and patterning.…”