Article
Engineering, Electrical & Electronic
Wenhao Zhang, Xiqi Wu, Wenting Wang, Kaidi Zhang, Bowen Li, Yuhang Chen
Summary: The on-demand modulation of material properties at the nanoscale is crucial for the development of functional micro- and nanodevices. This study focuses on modulating the structural and electric properties of vanadium dioxide (VO2) films using a locally confined atomic force microscope (AFM) tip-induced electric field. The time stability and reversibility of the modulation are investigated, and potential applications in developing optoelectronic devices with arbitrary shapes are demonstrated.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Monica Luna, Mariam Barawi, Sacha Gomez-Monivas, Jaime Colchero, Micaela Rodriguez-Pena, Shanshan Yang, Xiao Zhao, Yi-Hsien Lu, Ravi Chintala, Patricia Renones, Virginia Altoe, Lidia Martinez, Yves Huttel, Seiji Kawasaki, Alexander Weber-Bargioni, Victor A. de la Pena OShea, Peidong Yang, Paul D. Ashby, Miquel Salmeron
Summary: The study explores the impact of gold nanoparticles on TiO2 during illumination with photons of energy larger than the substrate band gap. It is found that photoinduced electron transfer from TiO2 to the Au NPs increases logarithmically with light intensity due to electron trapping, hindering electron-hole recombination and enhancing photo(electro)catalytic activity.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Minwoo Lee, Eunyoung Choi, Arman Mahboubi Soufiani, Jihoo Lim, Moonyong Kim, Daniel Chen, Martin Andrew Green, Jan Seidel, Sean Lim, Jincheol Kim, Xinchen Dai, Robert Lee-Chin, Bolin Zheng, Ziv Hameiri, Jongsung Park, Xiaojing Hao, Jae Sung Yun
Summary: This study presents an effective strategy to improve the performance of halide perovskite-based PV devices by using a hole-selective layer formed by PEAI salt, achieving high efficiency and stability under different light conditions.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Physical
Yuuki Adachi, Yasuhiro Sugawara, Yan Jun Li
Summary: Probing CO on a rutile TiO2(110) surface using atomic force microscopy and Kelvin probe force microscopy enables the resolution of the interatomic dipole moment and charge state of CO at atomic resolution. The results suggest that both charge state and on-surface dipole interaction play a significant role in the reaction of CO on rutile TiO2(110) surface.
Article
Chemistry, Physical
Tuan-Hoang Tran, Raul D. Rodriguez, Marco Salerno, Aleksandar Matkovic, Christian Teichert, Evgeniya Sheremet
Summary: Freshly cleaved HOPG shows time-evolving domains with surface potential contrast, attributed to locally different hydrocarbon adsorption driven by structural defects likely related to rotational mismatch. Raman spectroscopy results support the hypothesis of bilayer graphene behavior due to broken symmetry at the top surface. This indicates that the chemical and electrical properties of HOPG are more complex than generally believed.
Article
Chemistry, Physical
Myung Gi Ji, Qiang Li, Rana Biswas, Jaeyoun Kim
Summary: Experimental study of nanopatterned tribocharges on elastomer surfaces revealed distinct fast and slow decay components attributed to different tribocharging mechanisms, providing insights into the temporal behavior and stability of tribocharges at the nanoscale level.
Article
Chemistry, Multidisciplinary
Emilie Gachon, Patrick Mesquida
Summary: Collagen fibrils exhibit a surface charge dependency on longitudinal strain, becoming more positive within 10% strain and more negative between 10% to 17% strain. This change is correlated with fibril stiffness and may be influenced by structural rearrangements. Kelvin-probe force microscopy testing on fibrils attached to an extensible, thin polymer film allows for the determination of electrical surface potential.
Review
Chemistry, Multidisciplinary
Liu Yang, Yanyan Wang, Xu Wang, Shareen Shafique, Fei Zheng, Like Huang, Xiaohui Liu, Jing Zhang, Yuejin Zhu, Chuanxiao Xiao, Ziyang Hu
Summary: This review focuses on the application of atomic force microscopy (AFM)-based scanning probing techniques in investigating the local properties of polycrystalline photovoltaic materials. By studying the optoelectronic heterogeneities at grain interiors (GIs) and grain boundaries (GBs), it is possible to understand their critical roles in device performance and guide optimization. The potential of these AFM-based techniques in developing next-generation photovoltaics and optoelectronics is also discussed.
Article
Chemistry, Physical
Hyunhwa Lee, Passarut Boonmongkolras, Seongmoon Jun, Daehan Kim, Yujin Park, Jaehyuk Koh, Yong-Hoon Cho, Byungha Shin, Jeong Young Park
Summary: Mixed-halide perovskites show tunable optical properties and have potential applications in optoelectronics, but the phase segregation caused by halide ion migration hinders stable performance in solar cells. By conducting comprehensive measurements, we have revealed the mechanism of ion migration and observed that iodide ions predominantly cause halide segregation. The changes in band bending at grain boundaries indicate the migration of iodide ions towards grain boundaries and their influence on the formation of iodine-rich phases. This study provides insights into the mechanism of light-halide ion interactions.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
R. V. Gainutdinov, E. V. Selezneva, I. P. Makarova, A. L. Vasiliev, A. L. Tolstikhina
Summary: Surface properties of superprotonic (K1-x(NH4)(x))(3)H(SO4)(2) (x >= 0.57) single crystals and their evolution under humidity were investigated using optical polarization microscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDXS). Additional techniques such as atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM), and scanning capacitance force microscopy (SCFM) were employed. The study examined fresh and aged cleavage surfaces perpendicular and parallel to the c axis of the trigonal superprotonic phase, considering the influence of air humidity, material composition, and surface orientation. Results showed changes in surface morphology, conductivity, potential, and capacitance, with the formation of a modified layer containing new crystal phases during aging.
SOLID STATE IONICS
(2023)
Article
Materials Science, Multidisciplinary
Chin Chyi Loo, Sha Shiong Ng, Hung Wei Yu, Edward Yi Chang, Chang Fu Dee, Wei Sea Chang
Summary: This study reveals that threading dislocations (TDs) cause pits to form around the InN island boundaries, resulting in the high residual electron concentration in InN. Additionally, positively charged TDs contribute to the high positive current and surface potential observed at the InN island boundary regions.
MATERIALS CHARACTERIZATION
(2023)
Article
Materials Science, Multidisciplinary
Qin Ling, Qing Dai, Liu Yang, Like Huang, Xiaohui Liu, Houcheng Zhang, Jing Zhang, Yuejin Zhu, Ziyang Hu
Summary: This study investigates the spatial response of quasi-two-dimensional perovskites using complementary methods. The results reveal variations in the photovoltage across grains and grain boundaries, providing insight into the performance-limiting mechanisms and the development of efficient and stable 2D perovskite-based devices.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Chuanbiao Bie, Zheng Meng, Bowen He, Bei Cheng, Gang Liu, Bicheng Zhu
Summary: This study systematically investigates the transfer of photogenerated electrons in semiconductor/metal junctions. The results show that the behavior of electron transfer is determined by the position of the conduction band in the semiconductor and the Fermi level in the metal. Schottky junctions hinder the transfer of photogenerated electrons, while ohmic contacts facilitate it.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2024)
Article
Energy & Fuels
Christian Kameni Boumenou, Amala Elizabeth, Finn Babbe, Alice Debot, Harry Moeenig, Alex Redinger
Summary: The study investigated the buried MoSe2/CuInSe2 interface of stoichiometric absorbers in thin film solar cells, revealing differences in local density of states compared to the front-side properties. This sheds new light on the complex interface formation in CuInSe2-based thin film solar cells grown under Cu-rich conditions.
PROGRESS IN PHOTOVOLTAICS
(2021)
Article
Anatomy & Morphology
Joel Ndikumana, Kunsik An
Summary: We performed local surface potential mapping of pentacene film using scanning kelvin probe microscopy and found that grain boundaries behave as hole traps.
MICROSCOPY RESEARCH AND TECHNIQUE
(2023)
Article
Chemistry, Analytical
Haomin Wang, Le Wang, Eli Janzen, James H. Edgar, Xiaoji G. Xu
Summary: This article introduces the technique of achieving a 10 nm spatial resolution using peak force infrared microscopy in the TIR geometry. The method collects the photothermal responses of the sample in the peak force tapping mode of atomic force microscopy.
ANALYTICAL CHEMISTRY
(2021)
Article
Chemistry, Analytical
Haomin Wang, Joseph M. Gonzalez-Fialkowski, Wenqian Li, Qing Xie, Yan Yu, Xiaoji G. Xu
Summary: Peak force infrared (PFIR) microscopy is an advanced atomic force microscopy technique that allows surpassing Abbe's diffraction limit in chemical nanoimaging and spectroscopy. By developing liquid-phase peak force infrared (LiPFIR) microscopy, it enables in situ tracking and detection of chemical reactions in fluid environments, providing high-resolution infrared imaging and spectroscopy capabilities for soft matters and biological samples.
ANALYTICAL CHEMISTRY
(2021)
Article
Chemistry, Analytical
Yi Zhang, Celalettin Yurdakul, Alexander J. Devaux, Le Wang, Xiaoji G. Xu, John H. Connor, M. Selim Unlu, Ji-Xin Cheng
Summary: This study demonstrated a confocal interferometric mid-infrared photothermal microscope for ultra-sensitive and spatially resolved chemical imaging of individual viruses. The method detects the weak photothermal signal induced by infrared absorption of chemical bonds in viruses. The research shows the potential of using interferometric MIP microscopy for label-free differentiation of viral particles.
ANALYTICAL CHEMISTRY
(2021)
Article
Chemistry, Physical
Haomin Wang, Qing Xie, Yu Zhang, Xiaoji G. Xu
Summary: The study presents a new spectroscopic method to measure the excited-state absorption (ESA) based on mechanical detection of photothermal responses using peak force infrared (PFIR) microscopy. By collecting two-dimensional PFIR spectra on a polymer with ESA responses and spatially mapping the ESA response of a structured polymer, the study shows that the spatial resolution of pump-probe PFIR microscopy is not affected by the diffraction limit as it provides access to two-dimensional infrared nanoscopy.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Multidisciplinary Sciences
Nengxu Li, Xiuxiu Niu, Liang Li, Hao Wang, Zijian Huang, Yu Zhang, Yihua Chen, Xiao Zhang, Cheng Zhu, Huachao Zai, Yang Bai, Sai Ma, Huifen Liu, Xixia Liu, Zhenyu Guo, Guilin Liu, Rundong Fan, Hong Chen, Jianpu Wang, Yingzhuo Lun, Xueyun Wang, Jiawang Hong, Haipeng Xie, Devon S. Jakob, Xiaoji G. Xu, Qi Chen, Huanping Zhou
Summary: The liquid medium annealing (LMA) technology shows promise in producing high-quality perovskite films and photovoltaic devices with improved crystal growth modulation and film uniformity. This method opens up an effective avenue for scalable and reproducible quality improvement in perovskite films and devices.
Review
Pharmacology & Pharmacy
Haomin Wang, Qing Xie, Xiaoji G. Xu
Summary: This review article introduces a method to bypass the diffraction limit and improve the sensitivity for mid-IR methods using tip-enhanced light nearfield in AFM operated in tapping and peak force tapping modes. It briefly presents the working principles of well-established s-SNOM and two relatively new techniques, PiFM and PFIR microscopy. The recent applications and future improvements of these AFM-based nano-IR methods in revealing nanoscale chemical heterogeneities in biological systems are discussed.
ADVANCED DRUG DELIVERY REVIEWS
(2022)
Article
Chemistry, Analytical
Qing Xie, Jared Wiemann, Yan Yu, Xiaoji G. Xu
Summary: Dual-color PFIR microscopy enables simultaneous imaging at two infrared frequencies, overcoming the limitations of AFM frame drift and distortion. The technique demonstrates excellent performance and spatial resolution in imaging structured polymers and biological samples.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Analytical
Joseph M. Gonzalez-Fialkowski, Le Wang, Yongjie Li, Xiaoji G. Xu
Summary: Indoor aerosols can adversely affect human health, and one of the research challenges is measuring fine and ultrafine aerosol particles. The study observed a general heterogeneity in individual aerosol particles, and the PFIR microscopy is suitable for identifying the composition of aerosols.
ANALYTICAL CHEMISTRY
(2021)
Article
Chemistry, Physical
Qing Xie, Haomin Wang, Xiaoji G. Xu
Summary: In this article, the authors report the development of a dual-frequency peak force photothermal microscopy method based on atomic force microscopy. This method enables simultaneous infrared and visible imaging, allowing for the study of chemical distribution and localized heat generation in photovoltaic materials.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Analytical
Andrea Dorsa, Qing Xie, Martin Wagner, Xiaoji G. Xu
Summary: Nanoscale infrared (nano-IR) microscopy combines atomic force microscopy and infrared radiation for label-free chemical imaging with high spatial resolution. Peak force infrared (PFIR) microscopy, a emerging nano-IR method, offers non-destructive multimodal chemical and mechanical characterization using a simple photothermal signal generation mechanism. However, the current PFIR microscope requires customized hardware configuration and software programming, creating barriers to implementation.
Article
Chemistry, Multidisciplinary
Qing Xie, Xiaoji G. Xu
Summary: This study develops a Fourier transform AFM-IR technique with peak force infrared microscopy and broadband femtosecond IR pulses, enabling the mechanical detection of photothermal expansion caused by infrared absorption. The method bypasses Abbe's diffraction limit and allows for chemical imaging of materials. The intriguing observation of vertical asymmetry in the interferogram suggests the presence of multiphoton absorption processes.
Article
Chemistry, Multidisciplinary
Amirhossein Zahmatkeshsaredorahi, Devon S. Jakob, Hui Fang, Zahra Fakhraai, Xiaoji G. Xu
Summary: Kelvin probe force microscopy is a tool for measuring surface potential and providing insights into nanoscale electronic properties. We introduce a lock-in amplifier-based pulsed force Kelvin probe force microscopy (PF-KPFM) method to overcome instrument complexity and limited operational speed. We successfully apply this method to study the electrical properties of two-dimensional material MXene and aged perovskite photovoltaic films.
Article
Chemistry, Multidisciplinary
Qing Xie, Xiaoji G. Xu
Summary: In the past decade, there has been rapid development in atomic force microscopy-based photothermal infrared microscopy (AFM-IR) techniques, allowing for surface chemical imaging with spatial resolutions in the tens of nanometers. The availability of commercial AFM-IR instruments has increased their popularity in soft matter and surface science communities. Various AFM-IR modes with different characteristics exist, and in this Perspective, the challenges and opportunities associated with these modes are discussed, aiming to clarify any confusion arising from terminologies and highlighting the potential benefits of using multiple AFM-IR modes for a better understanding of the nanoscale composition organization at interfaces.
Review
Chemistry, Multidisciplinary
Le Wang, Haomin Wang, Xiaoji G. Xu
Summary: PFIR microscopy is an emerging infrared microscopy technique that utilizes an atomic force microscopy probe to mechanically detect the infrared response of a sample, achieving sub-10 nm spatial resolution for imaging and spectroscopy.
CHEMICAL SOCIETY REVIEWS
(2022)