Reduced Water Vapor Transmission Rate of Graphene Gas Barrier Films for Flexible Organic Field-Effect Transistors

Abstract

Preventing reactive gas species such as oxygen or water is important to ensure the stability and durability of organic electronics. Although inorganic materials have been predominantly employed as the protective layers, their poor mechanical property has hindered the practical application to flexible electronics. The densely packed hexagonal lattice of carbon atoms in graphene does not allow the transmission of small gas molecules. In addition, its outstanding mechanical flexibility and optical transmittance are expected to be useful to overcome the current mechanical limit of the inorganic materials. In this paper, we reported the measurement of the water vapor transmission rate (WVTR) through the 6-layer 10 × 10 cm(2) large-area graphene films synthesized by chemical vapor deposition (CVD). The WVTR was measured to be as low as 10(-4) g/m(2)·day initially, and stabilized at ∼0.48 g/m(2)·day, which corresponds to 7 times reduction in WVTR compared to bare polymer substrates. We also showed that the graphene-passivated organic field-effect transistors (OFETs) exhibited excellent environmental stability as well as a prolonged lifetime even after 500 bending cycles with strain of 2.3%. We expect that our results would be a good reference showing the graphene's potential as gas barriers for organic electronics.

Manufacturing and properties of biomimetic graphite nanoplatelets foils

“…The WVTR at RH of 50% and 75%, of the GNPCure70‐P1 are 1.2 and 1.6 g/(m 2 day), respectively. The barrier property is of the same order of magnitude of that measured in the case highly oriented multilayered graphene films synthesized by chemical vapor deposition (CVD) (0.48 g/(m 2 day) . In addition, recently , a WVTR of 7.4 g/(m 2 ·day) has been reported for an epoxy matrix nanocomposite containing graphene oxide nanoplatelets at 1% w/w.…”

Graphene-based nanolaminates as ultra-high permeation barriers

“…In contrast to previous reports on graphene barrier films which aimed at clean graphene layers with minimal polymer contamination, 19,20 here for WVTR measurement study we do not remove the PMMA layer and utilize it as: (a) protection during Ca oxidation since Ca is known to form micron scale protrusions which can penetrate through the barrier film and damage it, 37,38 (b) insulating layer when used as encapsulation coating for electronic devices separating the conductive graphene, and (c) ease of sample handling. We note that the WVTR of 0.3-µm thick PMMA is several orders higher, hence it will not affect on the measured values of graphene-based laminates.…”

“…These reports have highlighted the challenges of controlled "layering" of transferred graphene including the deleterious effect of polymer contamination. 19,20 A number of different processes to improve the performance of polymer-based barrier layers via the addition of graphene have been reported, 39 while O'Hern et al 26 have used polymer and ALD oxide deposition to "seal" practically unavoidable defects in larger-area monolayer graphene for nanofiltration applications. However, for barrier applications, in order to achieve low WVTRs the defects/pinholes in graphene cannot be effectively patched by polymers that show inherent high WVTRs.…”

“…/day, [19][20][21][22][23] which is at least two orders of magnitude too high to be suitable for organic devices. Barrier membranes based on (exfoliated) graphene or graphene oxide flakes inevitably have to be much thicker to compensate for the many possible permeation pathways, 24,25 which negates at least part of the advantages that 2D materials can offer.…”

The Analysis and Research for the Plate Differential Oxygen Gas Sensor of Auto Based on the Temperature Field and Thermal Stress Field

“…General exhaust gas is not sufficient for the sensor to reach this temperature [7]. In the traditional tubular oxygen sensors, an independent ceramic heater is introduced, which greatly shortens the time required for the response [6]. However, it is still unable to meet the exhaust emission vehicle (SULEV) response time requirements [9].…”