Transparent MESA structure TiO2 ChemicalCompound LateralForce Singapore Floppy Phenanthrene Perovskite SICM graphene_hybrid University_of_Regensburg Temasek_Lab bias_mode Optoelectonics Display Nanopattern Lattice Ferroelectric light_emitting SKKU FM_KPFM HanyangUniv STO ScanningKelvinProbeMicroscopy Epoxy Conductivity PiezoelectricForceMicroscopy Regensburg RedBloodCell KPFM Carbon tip_bias_mode Granada GaP