By combining contact-mode atomic force microscopy (AFM) and scanning Kevin probe microscopy (SKPM), we demonstrated an in situ method for quantitative characterization of the triboelectrification process at the nanoscale. We systematically characterized the triboelectric charge distribution, multifriction effect on charge transfer, as well as subsequent charge diffusion on the dielectric surface: (i) the SiO 2 surface can be either positively or negatively charged through triboelectric process using Si-based AFM probes with and without Pt coating, respectively; (ii) the triboelectric charges accumulated from multifriction and eventually reached to saturated concentrations of (−150 ± 8) μC/m 2 and (105 ± 6) μC/m 2 , respectively; (iii) the charge diffusion coefficients on SiO 2 surface were measured to be (1.10 ± 0.03) × 10 −15 m 2 /s for the positive charge and (0.19 ± 0.01) × 10 −15 m 2 /s for the negative charges. These quantifications will facilitate a fundamental understanding about the triboelectric and de-electrification process, which is important for designing high performance triboelectric nanogenerators. In addition, we demonstrated a technique for nanopatterning of surface charges without assistance of external electric field, which has a promising potential application for directed self-assembly of charged nanostructures for nanoelectronic devices. KEYWORDS: Triboelectric, atomic force microscopy, scanning Kelvin probe microscopy, nanogenerators, TENG C harge transfer between surfaces of two distinctly different materials through triboelectric effect is a well-known phenomenon 1−3 that has various applications such as powder spray painting, 4 electrophotography, 5,6 electrostatic separation, 7 and energy harvesting. 8 Recently, triboelectric nanogenerators (TENGs) have been invented for harvesting ambient mechanical energy based on the triboelectric effect coupled with electrostatic effect, and it has demonstrated unprecedented high output of its kind in both voltage and power density and efficiency, showing great promise for building self-powered portable electronics as well as possible large-scale energy harvesting. 9−11 Although the triboelectrification effect has been known for thousands of years, a fundamental understanding about it is rather limited. Research has been conducted to characterize the triboelectrification process using various methods such as rolling sphere tool-collecting induced charges from rolling spheres on top of a dielectric disk, 12−15 and using atomic force microscopy (AFM) to measure surface electrostatic force or potential on surfaces contacted by micropatterned materials. 16−18 However, these methods either lack an accurate control of the electrification process and/or cannot directly reveal the triboelectric interface, thus hardly achieving a quantitative understanding about the in situ triboelectric process.Here, we demonstrate an in situ method to quantitatively characterize the triboelectrification at nanoscale via a combination of contact-mode AFM and ...