Chemical Doping of Large-Area Stacked Graphene Films for Use as Transparent, Conducting Electrodes

Abstract

Graphene is considered a leading candidate to replace conventional transparent conducting electrodes because of its high transparency and exceptional transport properties. The effect of chemical p-type doping on graphene stacks was studied in order to reduce the sheet resistance of graphene films to values approaching those of conventional transparent conducting oxides. In this report, we show that large-area, stacked graphene films are effectively p-doped with nitric acid. The doping decreases the sheet resistance by a factor of 3, yielding films comprising eight stacked layers with a sheet resistance of 90 Omega/(square) at a transmittance of 80%. The films were doped either after all of the layers were stacked (last-layer-doped) or after each layer was added (interlayer-doped). A theoretical model that accurately describes the stacked graphene film system as a resistor network was developed. The model defines a characteristic transfer length where all the channels in the graphene films actively contribute to electrical transport. The experimental data shows a linear increase in conductivity with the number of graphene layers, indicating that each layer provides an additional transport channel, in good agreement with the theoretical model.

Inkjet printing of graphene

“…If we assume that the R s of a graphene lm scales with the resistance of the contact between two akes (R(CR)) and the resistance of the graphene ake itself (R(GF)), then the number of contacts would give a major contribution to the overall resistance. Here we assume that R s for a ake is approximately constant for all sizes as it depends on the defect density, [31][32][33] or doping, [34][35][36][37][38][39][40] etc. Since the large (90% of population >1 mm) graphene akes of EG + Plasdone S-630 assemble into a layer with fewer contacts between each other compared to a layer of the PNB-GCNF graphene (90% of population <60 nm), then the overall sheet resistance of the former lm (on both substrates) is much lower than that of the latter.…”

Efficient and bright organic light-emitting diodes on single-layer graphene electrodes

“…The unique electrical and mechanical properties of graphene make it an excellent choice for a flexible transparent conductor [16][17][18][19] . Graphene can be chemically doped to a carrier density of B10 13 cm À 2 while maintaining high carrier mobility 20,21 , leading to a surface resistance comparable to that of ITO.…”

Human‐Like Sensing and Reflexes of Graphene‐Based Films

“…Therefore, chemical heterogeneous doping is a useful method to improve the graphene sheet resistance. SOCl 2 ,60, 61 SOBr 2 ,62 HNO 3 ,7, 60, 62, 63, 64 and AuCl 3 64, 65 were commonly used as chemical dopants. The chemical dopants were always dissolved in a solvent and then spin‐coated onto the graphene film on the target substrate.…”