Reversible Charge-Transfer Doping in Graphene due to Reaction with Polymer Residues

Abstract

Chemical doping in graphene due to polymer molecules adsorption has attracted much recent interest because of the modification of electrical, magnetic, and optical properties of graphene. We show a reversible charge-transfer doping effect in graphene due to the reaction with poly(methyl methacrylate) (PMMA) residues. By helium ion irradiation and vacuum annealing without introducing an external dopant, reversible shifts in Raman G and 2D bands are observed as well as the change in the relative 2D band intensity to the G band. Chemical bonds between functional groups from PMMA residues and graphene could be formed due to He + ion irradiation, and the desorption of functional groups from graphene is dominant during the vacuum annealing process. Meanwhile, PMMA residue on the graphene surface is mostly removed and the surface morphology becomes smooth after irradiation and annealing. Both electrical conductance and Raman band shifts show nonmonotonic dependence on the dose density, which remains after annealing, indicating that the doping also involves an irreversible effect. Our study helps better the understanding of the doping effects in graphene due to polymer adsorption, which is efficient to tune the properties of graphene.

Graphene Electromechanical Water Sensor: The Wetristor

“…In agreement with Wehling et al, the atomically flat h‐BN lid has very low defect density and does not generate any charge transfer between graphene and water . Additionally, the rigid h‐BN lid does not allow the graphene membrane to change its conformation either, hence the morphology of the graphene remains unchanged or approximately constant, which leads to an unperturbed graphene resistivity in contact with water (as seen in Figure ) …”

“…The overall prediction, in the case of suspended graphene, is that the doping effects should be small and strongly dependent on molecule orientation. [49][50][51] Adv. [22] They predicted a very different doping behavior, as compared to suspended graphene: for defective SiO 2 substrates, adsorbed water molecules shift and couple the substrate's impurity bands with graphene bands, leading to much stronger (hole-type) doping, as compared to suspended graphene.…”

Potassium-neutralized perylene derivative (K4PTC) and rGO-K4PTC composite as effective and inexpensive electron transport layers for polymer solar cells

“…As shown in Fig. S1, no evident shift can be observed in G and 2D bands (1589 cm À1 and 2650 cm À1 ) of rGO-K 4 PTC, as compared with those of rGO, indicating negligible charge-transfer between the rGO and grafted K 4 PTC [36]. On the other hand, the samples of K 4 PTC and rGO-K 4 PTC drop-casting on silicon wafer were investigated by scanning electron microscope (SEM).…”

Annealing effect on UV-illuminated recovery in gas response of graphene-based NO2 sensors

“…This could be contributed by graphene suffering tensile strain from the glass substrate due to the difference in their thermal expansion coefficients and electron doping from the degradation of PMMA. 43,44 With temperature increasing to 400 C, the doping obviously changed to heavily p-type with a concentration of 5.9 Â 10 12 cm À2 . Hole doping by oxygen from glass substrate has been reported previously at an RTA temperature of 400 C in N 2 , 45 in addition to hole doping by annealing from 400 to 600 C. 46 The RTA with a fast heating rate followed by cooling down to room temperature within few minutes can induce thermal expansion coefficient mismatch between graphene and the glass substrate, which can cause compressive strain and hole doping on graphene.…”