Tetrachloroperylene diimide functionalized reduced graphene oxide sheets and their I–V behavior by current sensing atomic force microscopy

Abstract

Reduced graphene oxide (rGO) sheets covalently functionalized with n-type tetrachloroperylene diimide (PDI) and oligomeric PDI have been prepared by a two-step approach. Firstly, graphene oxide (GO) was modified by an amidation reaction with 3-aminopropyldimethylethoxylsilane or 3-aminopropyldiethoxylmethylsilane, during which GO was reduced thermally. They then react with the silanol modified PDI by dehydration condensation to obtain PDI and oligomeric PDI modified rGO (rGO–PDI and rGO–(PDI)_n). The successful preparation of rGO–PDI and rGO–(PDI)_n were confirmed by FTIR, Raman, X-ray photoelectron spectroscopy and XRD. The morphologies of rGO–PDI and rGO–(PDI)_n sheets were studied using AFM. It was found that surface morphologies and height of rGO–PDI and rGO–(PDI)_n sheets are dependent on the solvents used for casting due to differences in the solubility of PDI. Moreover, the fluorescence emission spectrum of rGO–PDI and rGO–(PDI)_n shows strong fluorescence quenching and blue shift, especially in ethanol. Current sensing atomic force microscopy (CSAFM) indicated that the rGO–PDI composite shows quite different electric conductivity and optical properties with grafting efficiency and different solvents used for casting. Significantly, the electronic conductivity of rGO–(PDI)_n increased by 2–3 orders of magnitude compared to rGO–PDI.