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Figure 1: Schematic of the roll-based production of graphene films grown on a copper foil.
The process includes adhesion of polymer supports, copper etching (rinsing) and dry transfer-printing on a target substrate. A wet-chemical doping can be carried out using a set-up similar to that used for etching.
图1：在铜箔上生长的石墨烯薄膜的辊基生产示意图。
该工艺包括聚合物载体的粘附、铜蚀刻（漂洗）和在目标基底上的干转印。湿化学掺杂可以使用类似于用于蚀刻的装置来进行。
Figure 2: Photographs of the roll-based production of graphene films.
a, Copper foil wrapping around a 7.5-inch quartz tube to be inserted into an 8-inch quartz reactor. The lower image shows the stage in which the copper foil reacts with CH4 and H2 gases at high temperatures. b, Roll-to-roll transfer of graphene films from a thermal release tape to a PET film at 120 °C. c, A transparent ultralarge-area graphene film transferred on a 35-inch PET sheet. d, Screen printing process of silver paste electrodes on graphene/PET film. The inset shows 3.1-inch graphene/PET panels patterned with silver electrodes before assembly. e, An assembled graphene/PET touch panel showing outstanding flexibility. f, A graphene-based touch-screen panel connected to a computer with control software.
图2：基于辊的石墨烯薄膜生产的照片。
铜箔包裹7.5英寸的石英管，插入8英寸的石英反应器。下图显示了铜箔在高温下与CH4和H2气体反应的阶段。b，在120 ℃下石墨烯膜从热剥离带到PET膜的卷到卷转移。c，转移到35英寸PET片上的透明超大面积石墨烯膜。d，石墨烯/PET薄膜上银糊电极的丝网印刷工艺。插图显示了组装前用银电极图案化的3.1英寸石墨烯/PET面板。e，一种组装的石墨烯/PET触摸面板，显示出出色的灵活性。f，一种基于石墨烯的触摸屏面板，通过控制软件连接到计算机。
Figure 3: Optical characterizations of the graphene films prepared using layer-by-layer transfer on SiO2/silicon and PET substrates.
a, Raman spectra of graphene films with different numbers of stacked layers. The left inset shows a photograph of transferred graphene layers on a 4-inch SiO2(300 nm)/silicon wafer. The right inset is a typical optical microscope image of the monolayer graphene, showing >95% monolayer coverage. A PMMA-assisted transfer method is used for this sample. b, UV–vis spectra of roll-to-roll layer-by-layer transferred graphene films on quartz substrates. The inset shows the UV spectra of graphene films with and without HNO3 doping. The right inset shows optical images for the corresponding number of transferred layers (1 × 1 cm2). The contrast is enhanced for clarity. c, Raman spectra of HNO3-doped graphene films, showing ∼18 cm−1 blueshift both for G and 2D peaks. D-band peaks are not observed before or after doping, indicating that HNO3 treatment is not destructive to the chemical bonds of graphene. d, XPS peaks of monolayer graphene films transferred on SiO2/Si substrates, showing typical redshift and broadening of carbon 1s peaks (C1s) caused by p-doping. The inset shows work-function changes (ΔΦ) with respect to doping time (lower x-axis) and number of stacked layers (upper x-axis), measure by UPS.
图3：在SiO2/Si和PET衬底上使用逐层转移制备的石墨烯膜的光学特性。
a，不同堆叠层数的石墨烯薄膜的Raman光谱。左图显示了4英寸SiO2（300 nm）/Si晶片上转移石墨烯层的照片。右图是单层石墨烯的典型光学显微镜图像，显示单层覆盖率>95%。PMMA辅助转移方法用于该样品。b，石英衬底上卷对卷逐层转移石墨烯膜的紫外—可见光谱。插图显示了掺杂和不掺杂硝酸的石墨烯薄膜的紫外光谱。右插图显示了相应数量的转移层（1 × 1 cm2）的光学图像。为了清晰起见，对比度得到了增强。c，掺杂硝酸的石墨烯薄膜的拉曼光谱，显示G峰和2D峰都有18 cm-1的蓝移。掺杂前后均未观察到D带峰，表明HNO3处理对石墨烯的化学键没有破坏性。d，转移到SiO2/Si衬底上的单层石墨烯薄膜的XPS峰，显示了由p掺杂引起的碳1s峰（C1s）的典型红移和展宽。插图显示了功函数随掺杂时间（下x轴）和堆叠层数（上x轴）的变化（ΔΦ），通过UPS测量。
Figure 4: Electrical characterizations of layer-by-layer transferred and HNO3-doped graphene films.
a, Sheet resistances of transferred graphene films using a roll-to-roll (R2R) dry-transfer method combined with thermal release tapes and a PMMA-assisted wet-transfer method. b, Comparison of sheet resistance from this research and transmittance plots taken from other references. The dashed arrows indicate the expected sheet resistances at lower transmittance. The scheme is borrowed from ref. 19. c, Electrical properties of a monolayer graphene Hall bar device in vacuum. Four-probe resistivity (left bottom inset) is measured as a function of gate voltage in the monolayer graphene Hall bar shown in the right inset at room temperature (black curve) and T = 6 K (red curve). The QHE effect at T = 6 K and B = 9 T is measured in the same device. The longitudinal resistivity ρxx and Hall conductivity σxy are plotted as a function of gate voltage. The sequence of the first three half-integer plateaus corresponding to ν = 2, 6 and 10, typical for single-layer graphene, are clearly seen. The Hall effect mobility of this device is μHall = 7,350 cm−2 V−1s−1 at 6 K (∼5,100 cm−2 V−1s−1 at 295 K). Scale bar (inset), 3 µm. d, Electromechanical properties of graphene-based touch-screen devices compared with ITO/PET electrodes under tensile strain. The inset shows the resistance change with compressive and tensile strain applied to the upper and lower graphene/PET panels, respectively.
图4：逐层转移和硝酸掺杂石墨烯薄膜的电学特性。
a，使用卷对卷（R2R）干转印方法结合热剥离带和PMMA辅助湿转印方法的转印石墨烯膜的片电阻。b，本研究的薄层电阻与其他参考文献的透射率图的比较。虚线箭头表示较低透射率下的预期薄板电阻。c，单层石墨烯Hall棒器件在真空中的电学性质。在室温（黑色曲线）和T=6 K（红色曲线）下，测量四探针电阻率（左下插图）作为右插图所示单层石墨烯Hall棒中栅极电压的函数。在同一装置中测量了T=6 K和B=9 T时的QHE效应。纵向电阻率ρxx和霍尔电导率σxy被绘制为栅极电压的函数。前三个半整数平台的序列分别对应于单层石墨烯典型的ν = 2、6和10，可以清楚地看到。该器件的霍尔效应迁移率在6 K时为μHall = 7,350 cm−2 V−1s−1（在295K时为∼5,100 cm−2 V−1s−1）。比例尺（插图），3 µm。d，拉伸应变下石墨烯基触摸屏器件与ITO/PET电极的机电性能比较。插图显示了分别施加到上部和下部石墨烯/PET板的压缩和拉伸应变的电阻变化。
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