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Polymer-based triboelectric nanogenerators (TENGs) have held promise due to their excellent interfacial conformity and ease of fabrication. However, the role of surface roughness in triboelectricity requires further study. In this study, we have manipulated the nano-/micro-scale roughness configuration in polydimethylsiloxane (PDMS) over a wide range of extents using various sandpaper-based templates. According to the power spectral density analysis, the spatial frequency of template-free PDMS exhibits several distinct bandwidth regions each with different fractal dimensions significantly higher than 2, despite having the lowest roughness value. In contrast, most template-based PDMS shows an entire spatial frequency region that scales nearly with a single power factor corresponding to a fractal dimension as low as 2, despite slight increases in roughness values. Consequently, the surface temperature gradient and output performance of TENG increased, following the trend of fractal dimension and roughness, but the surface potentials have remained almost invariant. However, excessive increases in the surface roughness cause the spatial frequency to be divided once again into several different bandwidth regions with different cutoffs and higher fractal dimensions. These results suggest that the performance of TENG can be controlled by tuning both surface roughness and self-affine properties over multiple scales. Specifically, adhesive interaction becomes dominant on surfaces with lower fractality, enhancing TENG performance due to the expanded contact area. This study sheds light on the relationship among triboelectricity, thermal dissipation, and topography. [ABSTRACT FROM AUTHOR]

In the last decade, contact electrification has gained attention for its potential in energy harvesting, addressing fundamental physics. Scanning probe microscopy (SPM) has evolved as a powerful platform, enabling the in situ characterization/manipulation of a sample's tribological/electrical properties at nanoscale. However, although both the sliding and tapping modes are available in the energy harvesting, the lateral sliding using contact mode SPM has predominantly been employed in triboelectric study. In this work, contact electrification on polydimethylsiloxane is investigated, using peak force tapping atomic force microscopy (PF‐AFM). As PF‐AFM quasi‐discretely offers vertical tapping motions of the probe with a regulated force amplitude, resembling a vertical‐type triboelectric nanogenerator, while minimizing lateral forces. The subsequent surface potential measurements reveal that the generated tribocharge is influenced by both the effective work function difference and energy dissipation at the interface. Furthermore, the accumulation of transferred charges is explored by measuring tip‐sample current during the PF‐AFM operation, showing the comparable results with the surface potential measurement. The results can be attributed to the contact potential difference assisted by the energy dissipation at the interface. This study offers an advanced opportunity to understand and study charge generation behavior based on surface properties without damaging the sample. [ABSTRACT FROM AUTHOR]

A corona discharge treatment (CDT) is utilized to maximize the performance of triboelectric nanogenerators (TENGs) by injecting extra electrons into the negative tribomaterials. Increased performance of CDT TENGs, however, exhibits rapid degradation due to the electron dissipation by air moisture or thermal emission. To overcome such drawbacks and circumvent such dissipation, the source of charges should be replaced with ionic charges. This study reports a Ag nanowires (NWs)‐embedded laminating structure (AeLS) with a unique fabrication procedure for ionic charge injection by CDT. The injection of ions is achieved by interlayer‐CDT (i‐CDT), in which positive charges are dissipated by Ag NWs, and the opposite negative ions can remain on the outmost surface. The AeLS TENGs with i‐CDT exhibit high performance, long‐term stability, and durability. It shows voltage, current, and maximum power outputs of 380 V, 15 µA, and 827 mW m−2, respectively. As a practical demonstration, rotational TENG integrated with a direct discharge system is realized, and its current and voltage reach 7.4 mA and 7800 V, respectively. This work can pave the way for the design of ion‐based TENGs with high performance and long‐lasting retention of triboelectric charges. [ABSTRACT FROM AUTHOR]

The electric power output of a piezoelectric nanogenerator (PENG) depends on the various physical parameters of the constituent materials, including the piezoelectric coefficient, Young's modulus, and dielectric constant. Herein, we report the mechanical and electrical properties of a poly(vinylidene fluoride)–BaTiO3 (PVDF–BTO) composite-based PENG. Variation of the BTO nanoparticle (NP) content enabled the systematic tuning of the physical parameters that are related to power generation in the composite. The Young's modulus of the PVDF–BTO composite initially increased, and then eventually decreased, with the increasing BTO content, which was probably due to the clustering effect of the high modulus BTO NPs. The dielectric constant of the composite continuously increased as the BaTiO3 content increased. The piezoelectric outputs were greatly enhanced at 10 wt% of BTO, where the Young's modulus was the highest. These results indicate that the Young's modulus plays an important role in the piezoelectric power generation of the composite-based PENGs. [ABSTRACT FROM AUTHOR]