The surface charge decay: A theoretical and experimental analysis

Navarro-Rodriguez, Mario; Palacios-Lidón, E.; Somoza, A. M.

doi:10.1016/j.apsusc.2022.155437

Cited by 9 publications

(7 citation statements)

References 47 publications

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“…Nevertheless, there are situations in which compensating the local surface potential through KPFM significantly enhances the precision of topography measurements, especially when the voltage between tip and sample is large. This is exemplified in Figure 2 , where the tip–rGO voltage is intentionally modified by charging the flakes through bringing the tip into contact while applying an external bias voltage to the tip [ 78 ] (see Supporting Information File 1 , section SI.3 for further details). Following the charging process, without activating the KPFM feedback ( Figure 2a ), there is a noticeable increase in the flake’s apparent height, reaching approximately 9 nm, while the typical height (about 2 nm) is restored only after turning on the KPFM loop ( Figure 2b and Supporting Information File 1 , section SI.3).…”

Section: Resultsmentioning

confidence: 99%

“…In a previous work, we studied the tip-less case, which we will use as the starting point for our model. Here, we just summarize the main aspects and refer to [ 78 ] for further details. Then, we include the tip influence by adding the appropriate boundary condition, which is time-dependent when the tip is oscillating and/or an AC voltage is applied.…”

Section: Resultsmentioning

confidence: 99%

“…Similarly, the two-dimensional charge density is defined as n ( x , y , t ) = lim a →0 a ρ( x , y , z = 0, t ). Now, applying charge conservation (continuity equation), Ohm’s law, and Gauss’ theorem to the gray surface element in the sample plotted in Figure 6 leads to [ 78 ]:…”

Section: Resultsmentioning

confidence: 99%

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Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

Navarro-Rodriguez,

Somoza,

Palacios-Lidon

2024

Beilstein J. Nanotechnol.

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An often observed artifact in atomic force microscopy investigations of individual monolayer flakes of 2D materials is the inaccurate height derived from topography images, often attributed to capillary or electrostatic forces. Here, we show the existence of a Joule dissipative mechanism related to charge dynamics and supplementing the dissipation due to capillary forces. This particular mechanism arises from the surface conductivity and assumes significance specially in the context of 2D materials on insulating supports. In such scenarios, the oscillating tip induces in-plane charge currents that in many circumstances constitute the main dissipative contribution to amplitude reduction and, consequently, affect the measured height. To investigate this phenomenon, we conduct measurements on monolayer flakes of co-deposited graphene oxide and reduced graphene oxide. Subsequently, we introduce a general model that elucidates our observations. This approach offers valuable insights into the dynamics of surface charges and their intricate interaction with the tip.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

Navarro-Rodriguez,

Somoza,

Palacios-Lidon

2024

Beilstein J. Nanotechnol.

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“…[10][11][12][13] Another unclear issue of triboelectric charge is how charges dissipate over time. [14] Previous studies have found that charges can dissipate due to diffusion of charge to an uncharged surface, [15] drift by surface conductance, [16,17] UV exposure, [18,19] breakdown by air, or via water molecules. [20,21] Water molecules adsorbed onto the surface accelerate charge dissipation.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Triboelectric Charge Stability by Air‐Stable Radicals

Im,

Frey,

Lacks

et al. 2023

Advanced Science

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This paper demonstrates that air‐stable radicals enhance the stability of triboelectric charge on surfaces. While charge on surfaces is often undesirable (e.g., static discharge), improved charge retention can benefit specific applications such as air filtration. Here, it is shown that self‐assembled monolayers (SAMs) containing air‐stable radicals, 2,2,6,6‐tetramethylpiperidin‐1‐yl)oxidanyl (TEMPO), hold the charge longer than those without TEMPO. Charging and retention are monitored by Kelvin Probe Force Microscopy (KPFM) as a function of time. Without the radicals on the surface, charge retention increases with the water contact angle (hydrophobicity), consistent with the understanding that surface water molecules can accelerate charge dissipation. Yet, the most prolonged charge retention is observed in surfaces treated with TEMPO, which are more hydrophilic than untreated control surfaces. The charge retention decreases with reducing radical density by etching the TEMPO‐silane with tetrabutylammonium fluoride (TBAF) or scavenging the radicals with ascorbic acid. These results suggest a pathway toward increasing the lifetime of triboelectric charges, which may enhance air filtration, improve tribocharging for patterning charges on surfaces, or boost triboelectric energy harvesting.

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“…Then, the surface potential distributions of trapped charges can be visualized by KPFM. KPFM has been employed for detecting the localized electrical properties (such as surface potential, work function, charge trapping, and charge recombination) of materials and devices at nanometer scale by scanning the electrostatic force between the AFM tip and the sample surface. − Recently, there also are many reports on the application of KPFM to the study of two-dimensional nanostructures. ,− In our experiments, KPFM is conducted by a dual pass process with amplitude modulation as shown in Figure a . At the first scan, the topography is scanned in the tapping mode.…”

mentioning

confidence: 99%

Charge-Localized Retention and Long-Term Memory Enabled by Cooperating Sterically Confined Molecular Crystallization with Spiro[fluorene-9,9′-xanthene]-Based Csp³-Hindrance

Wang,

Zhang,

Jin

et al. 2024

J. Phys. Chem. Lett.

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Charge localization of memory materials plays a crucial role in the endurance and retention ability of organic nonvolatile memory, which is completely opposite from the charge delocalization of high-mobility materials. However, charge transfer of both though-space and through-bond based on molecular design principles still faces challenges. Herein, a nonplanar wide-bandgap semiconductor with Csp 3 -hindrance (DOCH 3 -DDPA-SFX) has been designed and synthesized. An effective crystallization effect of self-assembled two-dimensional nanosheets on charge trapping dynamics and kinetics is visualized by Kelvin probe force microscopy (KPFM). The trapped charges are localized completely on a single nanosheet, which has better charge trapping and retention properties than an amorphous film. Meanwhile, crystallization also greatly improves structure stability. Combining DFT theoretical calculations, the mechanisms of localization and long-term retention are discussed. The steric crystallization effects on the charge localization will guide the effective design of single-component semiconducting charge-memory materials by molecular assembly and aggregate control for high-performance organic memory.

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The surface charge decay: A theoretical and experimental analysis

Cited by 9 publications

References 47 publications

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

Enhanced Triboelectric Charge Stability by Air‐Stable Radicals

Charge-Localized Retention and Long-Term Memory Enabled by Cooperating Sterically Confined Molecular Crystallization with Spiro[fluorene-9,9′-xanthene]-Based Csp³-Hindrance

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The surface charge decay: A theoretical and experimental analysis

Cited by 9 publications

References 47 publications

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

Exploring surface charge dynamics: implications for AFM height measurements in 2D materials

Enhanced Triboelectric Charge Stability by Air‐Stable Radicals

Charge-Localized Retention and Long-Term Memory Enabled by Cooperating Sterically Confined Molecular Crystallization with Spiro[fluorene-9,9′-xanthene]-Based Csp3-Hindrance

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Charge-Localized Retention and Long-Term Memory Enabled by Cooperating Sterically Confined Molecular Crystallization with Spiro[fluorene-9,9′-xanthene]-Based Csp³-Hindrance