Nanoscope 8

The electrical characteristics were recorded in a nitrogen-filled glove box by using a Keithley 2612 source meter and 2400 source meter. Surface morphologies of the deposited films were studied using an atomic force microscope (AFM, Veeco Multimode V) in the tapping mode. The grazing incidence X-ray diffraction (GIXRD) patterns of PDPP-TBT films were recorded using an X-ray diffractometer (Rigaku SmartLab). Irradiation of parallel CuK_α1,2 X-ray beam was fixed at a grazing incident angle of 0.5° and the detector was independently moved to collect the diffraction data with a step-size of 0.02°. The SKPM was performed in the AFM system (Bruker NanoScope 8) with metalized probes based on previous work62 . Heavily n-doped Si wafers were used as the substrates and the GO were sandwiched between 30 nm thick Al₂O₃ and 10 nm thick PMMA. Al₂O₃ were deposited using a Savannah 100 atomic layer deposition (ALD) system at a substrate temperature of 80°C. PMMA films were spin-casted on top of GO from a solution containing 3 mg/ml PMMA in toluene and then annealed at 120°C for 1 hr. Potential images were realized under the lift-mode with a pre-defined lift height of 50 nm.

STM observations were performed by using a Nanoscope IIIa and Nanoscope 8 multimode SPM (Bruker, MA). The STM tip was prepared from a mechanical cut of a Pt–Ir (90:10) wire. The polymers were dissolved in 1,2,4-trichlorobenzene to prepare 0.01–0.03 mM solutions. The solutions were dropped onto a freshly cleaved HOPG surface (ZYB grade, Momentive Performance Materials, OH). Observations were carried out at the HOPG/solvent interface. All the STM images were low pass filtered by using SPIP software (Image Metrology, Denmark). The tunneling conditions are described in each figure caption.