Due to its exceptional mechanical properties, graphene can be an ideal support for nanotransfer printing. However, in its as-received state, it is incompatible with some processes for preparing 2D arrays of colloidal nanoparticles from reverse micelle templating. By treating CVD graphene with low temperature annealing, we have created a universal carrier to transfer such nanoparticles onto organic surfaces, taking advantage of the activation of the graphene surface via oxygen plasma etching. Desorption of hydrocarbon contaminant species by low temperature annealing is essential to ensure that exposure of the CVD graphene to the plasma oxidizes the film rather than etching it, as confirmed by Raman, Attenuated Total Reflectance- Fourier Transform Infrared (ATR-FTIR), and X-ray photoelectron spectroscopy measurements. Upon transfer printing to an organic surface, the nanoparticles are sandwiched between the reduced graphene oxide-like layer and the organic surface as shown by scanning near-field optical microscopy (SNOM), making them ideal as an interlayer in organic devices. The combination of exposure to plasma and annealing gives two vectors for controlling the oxygen doping profile in the activated graphene on Cu, and suggests new avenues for patterning nanostructures in devices with processing sensitive active layers.

Nanostructure incorporation into devices plays a key role in improving performance, yet processes for preparing two-dimensional (2D) arrays of colloidal nanoparticles tend not to be universally applicable, particularly for soft and oxygen-sensitive substrates for organic and perovskite-based electronics. Here, we show a method of transferring reverse micelle-deposited (RMD) nanoparticles (perovskite and metal oxide) on top of an organic layer, using a functionalized graphene carrier layer for transfer printing. As the technique can be applied universally to RMD nanoparticles, we used magnetic (γ-Fe 2 O 3 ) and luminescent (methylammonium lead bromide (MAPbBr 3 )) nanoparticles to validate the transfer-printing methodology. The strong photoluminescence from the MAPbBr 3 under UV illumination and high intrinsic field of the γ-Fe 2 O 3 as measured by magnetic force microscopy (MFM), coupled with Raman measurements of the graphene layer, confirm that all components survive the transfer-printing process with little loss of properties. Such an approach to introducing uniform 2D arrays of nanoparticles onto sensitive substrates opens up new avenues to tune the device interfacial properties.

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