MonoLayer kelvin probe force microscopy ConductingPolymer cross section Domain OrganicSemiconductor LMF PinPointMode KelvinProbeForceMicroscopy Terrace BiVO4 BTO Hole Cross-section Tin disulfide DIWafer solar_cell ShenYang MolecularSelfAssembly atomic_layer CarbonNanotube NUS_NNI_Nanocore Polymer multi_layer TemperatureControllerStage MetalCompound Gong Reduction Tungsten_disulfide LFM AdhesionForce Cell SolarCell CHRYSALIS_INC Subhajjit