Fig. 2: The crack-free transfer and barrier performance of double-layer graphene barrier films.
From: Principles for fabricating moisture barrier films via stacked Janus graphene layers
a, b Typical OM images of graphene transferred onto PEN/PVDF supporting films with (a) and without (b) the RIE-based surface modification. The graphene wrinkles and cracks were highlighted by white arrows. Scale bar, 10 μm. Inset (a): Photograph of A3-sized as-fabricated double-layer graphene barrier film showing the Weiming Lake and Boya Tower at Peking University seen through the transparent graphene barrier films. Yellow dashed lines highlight the graphene region. c The intactness of the graphene transferred onto PVDF/PEN films (red) and the measured contact angle (blue) of PVDF solution on the graphene surface as a function of the RIE treatment time. The data are presented as the means ± standard deviation (SD), n = 50. Inset: Photographs of PVDF solution on graphene surface without (left) and with 10 s RIE treatment time (right), showing the contact angle of 47.8o and 12.0o, respectively. d Summaries of measured average roughness (Ra) of graphene grown on Cu (blue) and graphene transferred onto PVDF/PEN supporting films (red). The data are presented as the means ± SD, n = 20. Inset: Typical AFM images of graphene grown on Cu (right) and graphene transferred onto PVDF/PEN supporting films (left). Scale bar, 1 μm. e Measured normalized conductivity of Ca films covered by transferred multilayer graphene (blue) and as-fabricated double-layer graphene (red) as a function of the measurement time, showing WVTR values of 2 × 10−2 and 5 × 10−5 g/(m2·day) at 25 oC and 45% RH, respectively. The blue dash line is the fitting curve that was used to obtain the WVTR value. Inset: OM image of as-transferred multilayer graphene onto SiO2/Si substrate. Scale bar, 20 μm. Note that the WVTR value of our barrier films were measured after the storing in ambient environment of 3 months after the fabrication. f Summary of previously reported WVTR values of graphene-based barrier films as a function of graphene layers (blue)3,9,10,11,12,19,25,39,41,42,43, Al2O3/graphene composite barrier films (green)3,9,10,11,12,19,25,39,41,42,43, Al2O3-only barrier films (purple)19,30,31,32,44,45,46,47, and WVTR value in our work (red).
