Article
Chemistry, Multidisciplinary
Sayanti Samaddar, Jeff Strasdas, Kevin Janssen, Sven Just, Tjorven Johnsen, Zhenxing Wang, Burkay Uzlu, Sha Li, Daniel Neumaier, Marcus Liebmann, Markus Morgenstern
Summary: By studying the current-induced surface potential maps of graphene field-effect transistors, it was discovered that electron-electron scattering dominates in certain areas, exhibiting viscous flow phenomena, even at moderate mobility.
Article
Energy & Fuels
C-S Jiang, D. Albin, M. Nardone, K. J. Howard, A. Danielson, A. Munshi, T. Shimpi, C. Xiao, H. R. Moutinho, M. M. Al-Jassim, G. Teeter, W. Sampath
Summary: This paper investigates the stability and electric field distribution of CdTe devices with a structure of TCO/MZO/CdSeTe/CdTe/backcontact. The results show reversible transitions between the light-soak state (LSS) and the dark-soak state (DSS), but irreversible degradation occurs after long-hour light soaking at an elevated temperature. The electric field profiles at different states reveal the presence of a buried homojunction (BHJ) in the LSS and an increased electric field near the MZO/CdSeTe interface at the DgS.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Nanoscience & Nanotechnology
Jill Serron, Albert Minj, Valentina Spampinato, Alexis Franquet, Yevhenii Rybalchenko, Marie-Emmanuelle Boulon, Steven Brems, Henry Medina Silva, Yuanyuan Shi, Benjamin Groven, Renan Villarreal, Thierry Conard, Paul van der Heide, Thomas Hantschel
Summary: This study investigates the rapid intercalation of water vapor at the interface of transition metal dichalcogenides (TMDs) and sapphire, as well as between two TMD monolayers, and examines its impact on their electrical properties. The findings reveal that water vapor can intercalate rapidly within a few minutes and show partial reversibility under (ultra)-high vacuum conditions. Complete desorption of intercalated water clusters significantly enhances the electronic properties of TMDs, but also indicates that the characterization of TMD samples is significantly affected by the presence of water intercalation in air, inert environments, and even vacuum. Moreover, the study highlights a correlation between water intercalation and the presence of defects, contributing to the gradual degradation of TMDs as they age.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Shangzhi Gu, Wenyu Liu, Shuo Mi, Guoyu Xian, Jiangfeng Guo, Fei Pang, Shanshan Chen, Haitao Yang, Hong-Jun Gao, Zhihai Cheng
Summary: In this study, the twist angle-dependent work functions of twisted bilayer graphene (tBLG) were investigated using Kelvin probe force microscopy (KPFM) and Raman spectroscopy. The surface potentials of Bernal-stacked multilayer graphene were measured to determine the relationship between twist angle and surface potential. It was found that the work function of tBLG decreases and tends to saturate with increasing number of layers. Controlled annealing process showed that tBLG transforms into Bernal-stacked bilayer graphene. This research provides valuable insights into the twist angle-dependent surface potentials and electronic properties of tBLG.
Article
Chemistry, Multidisciplinary
Haijie Ben, Yong Liu, Xiao Liu, Xiufan Liu, Cancan Ling, Chuan Liang, Lizhi Zhang
Summary: Constructing a PDI/BiOI heterojunction with diffusion-controlled charge separation process through elaborately fabricated methods, the research reveals the effectiveness of diffusion-controlled driving force in enhancing photocatalytic activities. The study sheds light on the importance of diffusion-controlled charge separation and offers useful insights for the design of high-performance heterojunction photocatalysts for practical applications.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Physical
Hwi Je Woo, Seongchan Kim, Young-Jin Choi, Jeong Ho Cho, Seong Heon Kim, Young Jae Song
Summary: The work function of graphene devices on SiO2 substrates is studied using Kelvin probe force microscopy, revealing gate voltage-dependent work-function hysteresis. The inhomogeneous distribution of chemical species at the graphene/SiO2 interface leads to varying degrees of hysteresis across different positions on the graphene.
Article
Nanoscience & Nanotechnology
Woongbin Yim, Van Tu Nguyen, Quynh Thi Phung, Hwan Sik Kim, Yeong Hwan Ahn, Soonil Lee, Ji-Yong Park
Summary: The spatial distribution of photogenerated carriers in atomically thin MoS2 flakes and their correlation with photocurrent generation is investigated using Kelvin probe force microscopy. The study reveals that surface potential changes can image the vertical redistribution of photogenerated carriers, and the trapping of photogenerated holes at the interface between MoS2 and the substrate is the main mechanism for the photoresponse.
ACS APPLIED MATERIALS & INTERFACES
(2022)
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
Chemistry, Multidisciplinary
Mengkang Xu, Xinpeng Tian, Qian Deng, Qun Li, Shengping Shen
Summary: By introducing nanocracks and applying continuously varying mechanical loading, the evolution of flexoelectricity around the crack tips in SrTiO3, Ba0.67Sr0.33TiO3, and TiO2 samples has been successfully measured. This method provides a reliable way to identify the significance of the flexoelectric effect and may open a new avenue for the study of flexoelectricity involving multiple physics phenomena such as flexoelectronics and the flexo-photovoltaic effect.
Article
Chemistry, Physical
Jie Mao, Zhenao Gu, Yue Yu, Huijuan Liu, Jiuhui Qu, Xiaoqiang An
Summary: This study integrated visual observation techniques and material synthesis strategies to reveal the structure-activity relationship of a single BiVO4 photocatalyst, confirming the significance of facet engineering for enhancing photocatalytic activity.
ACS APPLIED ENERGY MATERIALS
(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, Multidisciplinary
Devon S. Jakob, Nengxu Li, Huanping Zhou, Xiaoji G. Xu
Summary: This article introduces a novel method to generate Coulombic force in KPFM, increasing the spatial resolution to approximately 25 nm. By integrating PiFM, high spatial resolution chemical distributions and surface potential maps can be obtained concurrently. This is expected to facilitate characterizations of nanoscale electrical properties of photoactive materials, semiconductors, and ferroelectric materials.
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, Physical
Chin Chyi Loo, Sha Shiong Ng, Wei Sea Chang
Summary: The recent progress in piezotronics and piezo-phototronics has revealed new methods for adjusting/enhancing the performance of GaN-based devices, and the photostrictive effect in GaN samples with InGaN/GaN MQWs can be elucidated through the combination of light-induced surface electric field and converse piezoelectric effect. The enhanced piezoelectric coefficient under laser illumination suggests the potential for adjustable photostrictive responses in optomechanical sensors/actuators by manipulating the strain state of MQWs.
Article
Chemistry, Multidisciplinary
Lingqiao Kong, Qiushi Ruan, Jingyuan Qiao, Pengyu Chen, Bingzhen Yan, Wei He, Wei Zhang, Chaoran Jiang, Chengjie Lu, Zhengming Sun
Summary: This study realizes unassisted photo-charging of zinc-air batteries by investigating anisotropic photogenerated charge separation on different representative semiconductors. The exceptional anisotropic charge separation on a ZnIn(2)S(4) photoelectrode is revealed, and the cause-and-effect relationship between photo-charge accumulation and photo-charging performance is verified. The achieved light-to-chemical energy conversion efficiency highlights the importance of anisotropic semiconductors for unassisted photo-charging of zinc-air batteries.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
J. E. Hirsch
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2020)
Letter
Multidisciplinary Sciences
J. E. Hirsch, F. Marsiglio
Article
Physics, Applied
J. E. Hirsch
Summary: Under the influence of the BCS-electron-phonon theory, experimentalists have discovered high temperature conventional superconductors in pressurized hydrides, while theorists have been predicting and explaining these findings. However, the alternative theory of hole superconductivity suggests that no superconductivity exists in these materials.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
J. E. Hirsch
Summary: This article points out that hysteresis in transport properties has never been reported for hydrides under pressure, and this phenomenon can determine whether they are superconductors.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2022)
Editorial Material
Physics, Multidisciplinary
J. E. Hirsch, F. Marsiglio
Article
Physics, Applied
J. E. Hirsch
Summary: The article briefly introduces the classification of superconducting materials and the success and failure of the existing theory in describing conventional superconductors. It suggests exploring the possibility of a single theory different from the conventional theory that may describe the superconductivity of all materials.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
J. E. Hirsch
Summary: Prozorov and Bud'ko analyzed the tin-inside-H3S Mossbauer experiment and concluded that it is consistent with the expected behavior of a type II superconductor. However, their analysis shows that the reported nuclear resonant scattering measurements are incompatible with the recently reported magnetization measurements.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2022)
Correction
Physics, Multidisciplinary
J. E. Hirsch, D. van der Marel
MATTER AND RADIATION AT EXTREMES
(2022)
Article
Physics, Multidisciplinary
J. E. Hirsch, F. Marsiglio
Summary: The Meissner effect, magnetic field expulsion, is a hallmark of superconductivity. Recent studies claimed to have found definitive evidence of the Meissner effect in sulfur hydride and lanthanum hydride under high pressure, but we argue that the evidence presented does not support the case for superconductivity in these materials. Combining previous experimental evidence, we strongly suggest that hydrides under pressure are not high-temperature superconductors.
MATTER AND RADIATION AT EXTREMES
(2022)
Article
Physics, Applied
J. E. Hirsch
Summary: This article discusses the current state of superconductivity theory, the bibliometric H-index, and H.C. Andersen's tale about the emperor's new clothes. It was first published in the APS Forum on Physics and Society quarterly newsletter in January 2020.
INTERNATIONAL JOURNAL OF MODERN PHYSICS B
(2023)
Article
Physics, Applied
J. E. Hirsch
Summary: Over the past 9 years, there has been extensive experimental evidence suggesting that hydrogen-rich materials under high pressure exhibit high-temperature superconductivity, in line with the conventional BCS-electron-phonon theory. The primary evidence comes from electrical resistance measurements, indicating significantly lower resistivity compared to the best normal metals within the limits of experimental accuracy. However, an alternative explanation is proposed to account for the vanishing resistance observed in these materials without invoking superconductivity.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2023)
Article
Physics, Applied
J. E. Hirsch
Summary: The resistive transition width of a newly discovered room temperature near-ambient-pressure hydride superconductor varies significantly between different samples, while the transition temperature remains almost constant. In the narrowest transitions, the transition width relative to Tc is only 0.014%. The observed behaviors, such as the vanishing critical current and unusually small normal state resistance, question the superconductivity of this system. Implications for other hydrides are also discussed.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2023)
Article
Physics, Applied
J. E. Hirsch, F. Marsiglio
Summary: Reference [1] provides evidence for magnetic field screening and subtle evidence for magnetic field expulsion in hydrides under high pressure, which supports the claim that these materials are high temperature superconductors. However, we point out that the data presented in different figures of Ref. [1] are inconsistent (i) with each other, (ii) with other work by the same authors on the same samples [2, 3], and (iii) with the expected behavior of standard superconductors. This suggests that the reported magnetic phenomena for these materials are not associated with superconductivity, undermining the claim that these materials are high temperature superconductors.
JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM
(2023)
Editorial Material
Multidisciplinary Sciences
J. E. Hirsch
Summary: Contrary to the current consensus, the author argues that the existing evidence for high-temperature superconductivity in hydrides under high pressure is not convincing. The author suggests that the focus of research should urgently shift to experimentally establish whether or not superconductivity exists in pressurized hydrides, instead of searching for new materials that may show unproven superconductivity signals at higher temperatures. The implications of a negative finding for the theoretical understanding of superconductivity are discussed.
NATIONAL SCIENCE REVIEW
(2023)
Article
Physics, Multidisciplinary
J. E. Hirsch, D. van der Marel
Summary: This study reports the analysis results of carbonaceous sulfur hydride material, finding that the measured raw data are inconsistent with the published data. These results have significant implications for the claim that the material is a room temperature superconductor.
MATTER AND RADIATION AT EXTREMES
(2022)
