amplitude_modulation India Bismuth piezoelectric force microscopy Formamidinium_lead_iodide CNT KAIST Polypropylene OpticalModulator Wonseok Materials Display Battery BFO HexagonalBoronNitride molecule BiVO4 STM Moire PolymerBlend Subhajjit Defect Polytetrafluoroethylene LDPE Ni81Fe19 ForceMapping Adhesion NTU light_emission Typhimurium Hair Pores FM-KPFM cross section PiezoelectricForceMicroscopy