Peak Force Infrared–Kelvin Probe Force Microscopy

Jakob, Devon S.; Wang, Haomin; Zeng, Gang; Otzen, Daniel E.; Yan, Yong; Xu, Xiaoji G.

doi:10.1002/ange.202004211

Cited by 12 publications

(17 citation statements)

References 53 publications

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“…These results indicate that FcTc 2 can prevent surface ions from migration to produce a more uniform and stable surface component distribution (Fig. 2H) ( 25 ). By contrast, ion migration and volatilization were more prone to occur in the control films, resulting in increased surface defects and affecting the operational stability of perovskite devices (fig.…”

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confidence: 90%

Organometallic-functionalized interfaces for highly efficient inverted perovskite solar cells

et al. 2022

Science

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Further enhancing the performance and stability of inverted perovskite solar cells (PSCs) is crucial for their commercialization. We report that the functionalization of multication and halide perovskite interfaces with an organometallic compound, ferrocenyl-bis-thiophene-2-carboxylate (FcTc 2 ), simultaneously enhanced the efficiency and stability of inverted PSCs. The resultant devices achieved a power conversion efficiency of 25.0% and maintained >98% of their initial efficiency after continuously operating at the maximum power point for 1500 hours under simulated AM1.5 illumination. Moreover, the FcTc 2 -functionalized devices passed the international standards for mature photovoltaics (IEC61215:2016) and have exhibited high stability under the damp heat test (85°C and 85% relative humidity).

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confidence: 90%

Organometallic-functionalized interfaces for highly efficient inverted perovskite solar cells

et al. 2022

Science

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“…Mid-infrared (mid-IR) spectroscopy has attracted extensive attentions for interfacial studies since IR absorption of molecules arises from specific chemical bonds, allowing the analysis of molecular structures and functions without labelling or destruction. 1,2 Recently, atomic force microscopy (AFM) based opto-mechanical force detection techniques such as photothermal induced resonance (PTIR), [3][4][5][6] photoinduced force microscopy (PiFM) [7][8][9][10] and peak force infrared (PFIR) [11][12][13] microscopy have been demonstrated to achieve IR analysis with nanoscale spatial resolution, allowing subwavelength scale investigation of chemical and physical properties of molecules. At solid/gas interfaces, the detection sensitivity has hinted at molecular monolayer level, 3,7 which is promising to reveal information about the mechanisms of interfacial processes.…”

Section: Introductionmentioning

confidence: 99%

Antenna Enhanced Infrared Photoinduced Force Imaging in Aqueous Environment with Super-Resolution and Hypersensitivity

Pang

Yan

et al. 2022

CCS Chem

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Tip enhanced IR spectra and imaging have been widely used in cutting-edge studies for the indepth understanding of the composition, structure and function of interfaces at the nanoscale. However, molecular monolayer sensitivity has only been demonstrated at solid/gas interfaces. In aqueous environment, the reduced sensitivity limits the practical applications of tip enhanced IR nanospectroscopy. Here, we demonstrate an approach to hypersensitive nanoscale IR spectra and imaging in aqueous environment with the combination of photoinduced force (PiF) microscopy and resonant antennas. The highly confined electric field inbetween the tip and antenna amplifies the PiF, while the excitation via plasmon internal reflection mode minimizes the environmental absorption. A polydimethylsiloxane (PDMS) layer (~1-2 nm thickness) functionalized on the AFM tip and self-assembled monolayer of bovine hemoglobin on antenna has been successfully identified in water with antennas of different sizes. Sampling volume of ~604 chemical bonds from PDMS was demonstrated with sub-10 nm spatial resolution confirmed by electric field distribution mapping on antennas. This platform demonstrates for the first time the application of PiF microscopy in aqueous environments, providing a brand-new configuration to achieve highly enhanced nanoscale IR signals, which is promising for future research of interfaces and nanosystems in aqueous environments.

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“…The integration of the FET-switched KPFM with PiFM provides a route for simultaneous and correlative surface potential and chemical nanoimaging. Compared with the recent pulsed force mode based peak force infrared-Kelvin probe force microscopy (PFIR-KPFM) that also simultaneous yield chemical and surface potential mapping, [58] the integrated FETswitched KPFM with PiFM has a simpler design of signal processing. The data collection and processing is achieved with a two-channel lock-in amplifier with a PID option in a commercially available device.…”

Section: Discussionmentioning

confidence: 99%

Integrated Tapping Mode Kelvin Probe Force Microscopy with Photoinduced Force Microscopy for Correlative Chemical and Surface Potential Mapping

Jakob

Zhou

et al. 2021

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the sample through the measurement of Coulomb force and typically operates in the tapping mode of atomic force microscopy (AFM). [10] The tapping mode AFM operation avoids excess tip-sample contact and is advantageous for preserving the integrity of the sample surface, compared with the contact mode AFM. Besides, AFM imaging in the tapping mode can operate at a higher scan rate than the pulsed force mode. [11][12][13] Although the recent development of KPFM in the pulsed force mode considerably improves the spatial resolution on mapping surface potential under ambient conditions, its operational speed is limited by the subresonance tapping frequency of the pulsed force mode. [14] In comparison, a regular tapping mode operates with a cantilever resonant frequency of hundreds of kilohertz, whereas the pulsed force mode can operate only at a few kilohertz. The upper limit of the potential operational speed of KPFM in the tapping mode should be faster than that of the pulsed force KPFM. The limitations of the current popular tapping mode KPFM are associated with its operational mechanism. [15] Although the original design of the Kelvin probe method by Lord Kelvin for macroscopic measurement did not involve applying an AC voltage, [16] the tapping mode KPFM variants for nanoscopic measurement implement an external AC voltage between the tip and the sample to modulate the electrical force. A DC bias voltage is used under a negative feedback loop to minimize the electrical force-induced cantilever oscillation amplitude at the AC voltage frequency or the frequency shift of the cantilever oscillation at the tapping frequency. [17] Under ambient conditions, the amplitude of the AC drive voltage is often within the range of 1-5 V, posing a risk to voltage-sensitive materials, wherein tip-induced band-bending and charge transfer may generate significant artifacts in the images. [18,19] Furthermore, irreversible sample or tip damage from the large amplitude AC voltage may occur during KPFM measurements if the tip and sample come into unwanted transient contact (e.g., due to external vibrations and noises), even if the AFM is operated in the noncontact or attractive regime of the tapping mode. One way to reduce external noise is to use a low-temperature and ultrahigh vacuum system. However, such systems introduce additional experimental complexity. Therefore, a dual-pass lift Kelvin probe force microscopy (KPFM) is a popular technique for mapping the surface potential at the nanoscale through measurement of the Coulombic force between an atomic force microscopy (AFM) tip and sample. The lateral resolution of conventional KPFM variants is limited to between ≈35 and 100 nm in ambient conditions due to the long-range nature of the Coulombic force. In this article, a novel way of generating the Coulombic force in tapping mode KPFM without the need for an external AC driving voltage is presented. A field-effect transistor (FET) is used to directly switch the electrical connectivity of the tip and sample on and off periodically. The...

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Peak Force Infrared–Kelvin Probe Force Microscopy

Cited by 12 publications

References 53 publications

Organometallic-functionalized interfaces for highly efficient inverted perovskite solar cells

Organometallic-functionalized interfaces for highly efficient inverted perovskite solar cells

Antenna Enhanced Infrared Photoinduced Force Imaging in Aqueous Environment with Super-Resolution and Hypersensitivity

Integrated Tapping Mode Kelvin Probe Force Microscopy with Photoinduced Force Microscopy for Correlative Chemical and Surface Potential Mapping

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