Two‐dimensional ferroelectric (FE) heterostructures have recently become a subject of great interest due to their potential device applications and the underlying physics involved. In this study, we employ the first‐principles calculations to examine the FE control of electronic structures in 2D FE heterostructures, specifically In2Se3/h‐BN and CuInP2S6(CIPS)/h‐BN. Our results demonstrate that by reversing the polarization of the FE layers, the band alignment of the heterostructures can be interconverted between type−II and type−I. For In2Se3/h‐BN, the variation of out‐of‐plane polarization can be attributed to the hindrance and facilitation of charge transfer from h‐BN to In2Se3 by the intrinsic electric field of the In2Se3 monolayer. For CIPS/h‐BN heterostructures, the higher transferred charge in the Cdn configuration due to the presence of built‐in electric fields and the stronger interfacial interaction in the Cdn configuration results in a higher polarization value compared to the Cdn configuration. Moreover, the carrier mobility of the heterostructures can also be effectively modulated by the FE polarization. These findings highlight the potential significance of FE heterostructures with tunable band alignment and band gap in the development of nanoscale optoelectronic devices.This article is protected by copyright. All rights reserved.
二维铁电（FE）异质结构因其潜在的器件应用和所涉及的基础物理学而成为近期备受关注的课题。在本研究中，我们采用第一性原理计算来研究二维铁电异质结构（特别是 In2Se3/h-BN 和 CuInP2S6(CIPS)/h-BN 异质结构）中铁电对电子结构的控制。我们的研究结果表明，通过逆转 FE 层的极化，异质结构的能带排列可以在 II 型和 I 型之间相互转换。对于 In2Se3/h-BN，面外极化的变化可归因于 In2Se3 单层的本征电场阻碍和促进了电荷从 h-BN 向 In2Se3 的转移。对于 CIPS/h-BN 异质结构，由于存在内置电场，Cdn 构型中的电荷转移量更高，而且 Cdn 构型中的界面相互作用更强，因此极化值比 Cdn 构型更高。此外，异质结构的载流子迁移率也可以通过 FE 极化得到有效调节。这些发现凸显了具有可调带排列和带隙的 FE 异质结构在开发纳米级光电器件中的潜在意义。本文受版权保护。
{"title":"Ferroelectric Control of Band Alignments in In2Se3/h‐BN and CuInP2S6/h‐BN Van der Waals Heterostructures","authors":"Songmin Liu, Pan Zhou, Pengfei Hou, Lizhong Sun","doi":"10.1002/pssr.202300479","DOIUrl":"https://doi.org/10.1002/pssr.202300479","url":null,"abstract":"Two‐dimensional ferroelectric (FE) heterostructures have recently become a subject of great interest due to their potential device applications and the underlying physics involved. In this study, we employ the first‐principles calculations to examine the FE control of electronic structures in 2D FE heterostructures, specifically In2Se3/h‐BN and CuInP2S6(CIPS)/h‐BN. Our results demonstrate that by reversing the polarization of the FE layers, the band alignment of the heterostructures can be interconverted between type−II and type−I. For In2Se3/h‐BN, the variation of out‐of‐plane polarization can be attributed to the hindrance and facilitation of charge transfer from h‐BN to In2Se3 by the intrinsic electric field of the In2Se3 monolayer. For CIPS/h‐BN heterostructures, the higher transferred charge in the Cdn configuration due to the presence of built‐in electric fields and the stronger interfacial interaction in the Cdn configuration results in a higher polarization value compared to the Cdn configuration. Moreover, the carrier mobility of the heterostructures can also be effectively modulated by the FE polarization. These findings highlight the potential significance of FE heterostructures with tunable band alignment and band gap in the development of nanoscale optoelectronic devices.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"20 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139797592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yutao Niu, Ting Xu, Kun Meng, Xiuhan Li, Yan Wei, Yannan Zhang, Xiaohua Yu, Ju Rong
The insufficiency of freshwater supplies has posed a serious threat to sustainable socio‐economic growth, and seawater desalination is considered to be the most promising solution to alleviate such pressure. Currently, two‐dimensional (2D) carbon membranes are identified as deserving candidates since their high permeability and multiple tunable properties. However, they remain challenging to systematically uncover the potential relationships between structures and properties in various 2D carbon materials. For this, we trained a machine learning (ML) model based on feature datasets of 2D carbon materials effecting desalination properties. The results suggest that structures with a maximum pore size of 10‐12 atoms and atomic densities between 0.28 and 0.41 are more likely to achieve high properties. We selected the Cml‐MOR based on MOR type mordenite zeolite for validation. Further, Cml‐MOR is demonstrated to feature remarkable salt ion adsorption. The effective water flux of Cml‐MOR is 113.51 L·cm‐2·day‐1·MPa‐1, and the salt rejection at 110 MPa could reach to 98.9%. This work is expected to apply this efficient method to investigate the structure and properties of 2D carbon membranes with great structural diversity; this will attract more people to focus on them and explore their important potential for practical applications.This article is protected by copyright. All rights reserved.
{"title":"Data‐driven strategies for accelerated structural exploration of high‐performance two‐dimensional carbon‐based seawater desalination membranes","authors":"Yutao Niu, Ting Xu, Kun Meng, Xiuhan Li, Yan Wei, Yannan Zhang, Xiaohua Yu, Ju Rong","doi":"10.1002/pssr.202300403","DOIUrl":"https://doi.org/10.1002/pssr.202300403","url":null,"abstract":"The insufficiency of freshwater supplies has posed a serious threat to sustainable socio‐economic growth, and seawater desalination is considered to be the most promising solution to alleviate such pressure. Currently, two‐dimensional (2D) carbon membranes are identified as deserving candidates since their high permeability and multiple tunable properties. However, they remain challenging to systematically uncover the potential relationships between structures and properties in various 2D carbon materials. For this, we trained a machine learning (ML) model based on feature datasets of 2D carbon materials effecting desalination properties. The results suggest that structures with a maximum pore size of 10‐12 atoms and atomic densities between 0.28 and 0.41 are more likely to achieve high properties. We selected the Cml‐MOR based on MOR type mordenite zeolite for validation. Further, Cml‐MOR is demonstrated to feature remarkable salt ion adsorption. The effective water flux of Cml‐MOR is 113.51 L·cm‐2·day‐1·MPa‐1, and the salt rejection at 110 MPa could reach to 98.9%. This work is expected to apply this efficient method to investigate the structure and properties of 2D carbon membranes with great structural diversity; this will attract more people to focus on them and explore their important potential for practical applications.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"5 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139525963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vitomir Sever, Nicolas Bernier, Damien Térébénec, C. Sabbione, Jessy Paterson, F. Castioni, Patrick Quéméré, A. Jannaud, J. Rouviere, Hervé Roussel, J. Raty, Françoise Hippert, Pierre Noé
Scanning Transmission Electron Microscopy (STEM) techniques are used to improve our understanding of out‐of‐plane oriented Sb2Te3 thin films deposited by sputtering on SiO2 and Si substrates. Nanobeam Precession Electron Diffraction (N‐PED), Energy‐Dispersive X‐ray spectroscopy (EDX) and High‐Angle Annular Dark‐Field (HAADF) imaging show that the presence of one to two atomic planes of Te on top of the substrate is a crucial factor for successful growth of such films, which can be achieved by optimizing co‐sputtering of Te and Sb2Te3 targets. The formation of an actual van der Waals (vdW) gap between the substrate and the first Sb2Te3 quintuple layer (QL) allows for vdW epitaxy. This gap is larger than those separating Te planes in the pseudo‐2D Sb2Te3 structure. HAADF image analysis provides detailed information on the atomic arrangement such as interplanar distances, vdW gaps and Debye Waller coefficients, all these with a few pm precision. For the anisotropic atomic displacements, a new methodology is introduced based on the statiscal analysis of atomic column positions that provides information on the low‐frequency phonon modes. Ab‐initio calculations are used to support our results. Overall, this study provides quantitative STEM tools particularly well suited for non periodic pseudo‐2D materials, such as Sb2Te3/GeTe super‐lattices.This article is protected by copyright. All rights reserved.
扫描透射电子显微镜（STEM）技术用于加深我们对通过溅射法沉积在二氧化硅和硅基底上的面外取向 Sb2Te3 薄膜的了解。纳米束前序电子衍射 (N-PED)、能量色散 X 射线光谱 (EDX) 和高角度环形暗场 (HAADF) 成像显示，基底顶部存在一到两个 Te 原子面是成功生长此类薄膜的关键因素，而这可以通过优化 Te 和 Sb2Te3 靶材的共溅射来实现。在基底和第一个 Sb2Te3 五重层 (QL) 之间形成一个实际的范德华 (vdW) 间隙可以实现 vdW 外延。该间隙大于伪二维 Sb2Te3 结构中 Te 平面之间的间隙。HAADF 图像分析提供了原子排列的详细信息，如平面间距、vdW 间隙和 Debye Waller 系数，所有这些信息的精度仅为几微米。对于各向异性的原子位移，引入了一种基于原子柱位置静态分析的新方法，可提供低频声子模式的信息。我们使用 Ab-initio 计算来支持我们的结果。总之，这项研究提供了定量 STEM 工具，特别适用于非周期性伪二维材料，如 Sb2Te3/GeTe 超晶格。本文受版权保护。
{"title":"Quantitative STEM HAADF Study of the Structure of pseudo‐2D Sb2Te3 films grown by (quasi) van der Waals Epitaxy","authors":"Vitomir Sever, Nicolas Bernier, Damien Térébénec, C. Sabbione, Jessy Paterson, F. Castioni, Patrick Quéméré, A. Jannaud, J. Rouviere, Hervé Roussel, J. Raty, Françoise Hippert, Pierre Noé","doi":"10.1002/pssr.202300402","DOIUrl":"https://doi.org/10.1002/pssr.202300402","url":null,"abstract":"Scanning Transmission Electron Microscopy (STEM) techniques are used to improve our understanding of out‐of‐plane oriented Sb2Te3 thin films deposited by sputtering on SiO2 and Si substrates. Nanobeam Precession Electron Diffraction (N‐PED), Energy‐Dispersive X‐ray spectroscopy (EDX) and High‐Angle Annular Dark‐Field (HAADF) imaging show that the presence of one to two atomic planes of Te on top of the substrate is a crucial factor for successful growth of such films, which can be achieved by optimizing co‐sputtering of Te and Sb2Te3 targets. The formation of an actual van der Waals (vdW) gap between the substrate and the first Sb2Te3 quintuple layer (QL) allows for vdW epitaxy. This gap is larger than those separating Te planes in the pseudo‐2D Sb2Te3 structure. HAADF image analysis provides detailed information on the atomic arrangement such as interplanar distances, vdW gaps and Debye Waller coefficients, all these with a few pm precision. For the anisotropic atomic displacements, a new methodology is introduced based on the statiscal analysis of atomic column positions that provides information on the low‐frequency phonon modes. Ab‐initio calculations are used to support our results. Overall, this study provides quantitative STEM tools particularly well suited for non periodic pseudo‐2D materials, such as Sb2Te3/GeTe super‐lattices.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"7 16","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139526113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kai-Yue Jiang, Yu-Lin Han, Mei-Yan Ni, Hong-Yan Lu
Although hydrides such as have been experimentally confirmed to possess high superconducting critical temperature () of 250‐260 K under 170‐200 GPa, it is still a tough challenge to be applied. It is highly anticipated to find hydride superconductors with relatively high at low or ambient pressure. Reducing the dimensionality of materials can induce unexpected properties that are distinct from their bulk counterparts, whether it can modulate the superconducting properties deserves further investigation. Here, we theoretically predict a new two‐dimensional (2D) monolayer aluminum hydride h‐ under ambient pressure based on the first‐principles calculations. Since the electronic structures of h‐ reveal the metallicity, the electron‐phonon coupling (EPC) and possible phonon‐mediated superconductivity have been investigated. Based on the isotropic Eliashberg equation, the calculated EPC constant λ of h‐ is 1.16, and the is up to 42.6 K. The EPC mainly originates from the coupling between electrons of Al‐s,,, and H‐s orbitals and the in‐plane vibration modes of H atoms. Especially, the can be enhanced to 63.7 K by applying 3% biaxial tensile strain. Thus, the predicted h‐ provides a new platform for finding hydride superconductors in low‐dimensional materials at ambient pressure.This article is protected by copyright. All rights reserved.
{"title":"Prediction of High‐Temperature Superconductivity in Monolayer h‐AlH2$left(text{AlH}right)_{2}$ at Ambient Pressure","authors":"Kai-Yue Jiang, Yu-Lin Han, Mei-Yan Ni, Hong-Yan Lu","doi":"10.1002/pssr.202300417","DOIUrl":"https://doi.org/10.1002/pssr.202300417","url":null,"abstract":"Although hydrides such as have been experimentally confirmed to possess high superconducting critical temperature () of 250‐260 K under 170‐200 GPa, it is still a tough challenge to be applied. It is highly anticipated to find hydride superconductors with relatively high at low or ambient pressure. Reducing the dimensionality of materials can induce unexpected properties that are distinct from their bulk counterparts, whether it can modulate the superconducting properties deserves further investigation. Here, we theoretically predict a new two‐dimensional (2D) monolayer aluminum hydride h‐ under ambient pressure based on the first‐principles calculations. Since the electronic structures of h‐ reveal the metallicity, the electron‐phonon coupling (EPC) and possible phonon‐mediated superconductivity have been investigated. Based on the isotropic Eliashberg equation, the calculated EPC constant λ of h‐ is 1.16, and the is up to 42.6 K. The EPC mainly originates from the coupling between electrons of Al‐s,,, and H‐s orbitals and the in‐plane vibration modes of H atoms. Especially, the can be enhanced to 63.7 K by applying 3% biaxial tensile strain. Thus, the predicted h‐ provides a new platform for finding hydride superconductors in low‐dimensional materials at ambient pressure.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"3 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139380393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Keyun Gu, Zilong Zhang, K. Tang, Jian Huang, Yue Shen, Haitao Ye, Linjun Wang
The development of the fabrication methods with a simple process and high controllability for the β‐Ga2O3, especially for the nanowires structure, has been a challenge. The slanted Ga2O3 nanowires are favorable for increasing the optical contact area and improving photon flux through nanoparticle scattering, leading to an increase in the photogenerated carrier yield. In this work, obliquely oriented and uniformly distributed β‐Ga2O3 nanowires were fabricated on Si substrates by RF magnetron sputtering using the strategy of Au nanoparticles as an intermediate catalyst. By depositing Ti and Au electrodes, we created the metal‐semiconductor‐metal (MSM) Ga2O3‐based photodetectors with a simple structure. Remarkably, the photodetector based on the β‐Ga2O3 nanowires outperformed the one based on the β‐Ga2O3 film, demonstrating higher responsivity and an exceptional photo‐current to dark‐current ratio (I photo /I dark ) of 1.43×104 @5 V. This work presents a promising approach to enhance the utilization of incident light and maximize the generation of photo‐induced carriers in the Ga2O3‐based photodetectors.This article is protected by copyright. All rights reserved.
{"title":"Enhanced performance of solar‐blind UV photodetector based on β‐Ga2O3 nanowires grown by a magnetron sputtering","authors":"Keyun Gu, Zilong Zhang, K. Tang, Jian Huang, Yue Shen, Haitao Ye, Linjun Wang","doi":"10.1002/pssr.202300291","DOIUrl":"https://doi.org/10.1002/pssr.202300291","url":null,"abstract":"The development of the fabrication methods with a simple process and high controllability for the β‐Ga2O3, especially for the nanowires structure, has been a challenge. The slanted Ga2O3 nanowires are favorable for increasing the optical contact area and improving photon flux through nanoparticle scattering, leading to an increase in the photogenerated carrier yield. In this work, obliquely oriented and uniformly distributed β‐Ga2O3 nanowires were fabricated on Si substrates by RF magnetron sputtering using the strategy of Au nanoparticles as an intermediate catalyst. By depositing Ti and Au electrodes, we created the metal‐semiconductor‐metal (MSM) Ga2O3‐based photodetectors with a simple structure. Remarkably, the photodetector based on the β‐Ga2O3 nanowires outperformed the one based on the β‐Ga2O3 film, demonstrating higher responsivity and an exceptional photo‐current to dark‐current ratio (I\u0000photo\u0000\u0000/I\u0000dark\u0000) of 1.43×104 @5 V. This work presents a promising approach to enhance the utilization of incident light and maximize the generation of photo‐induced carriers in the Ga2O3‐based photodetectors.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"52 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138950133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electron waves of a host system exhibit an oscillating response to an external impurity, namely Friedel oscillations, extensively studied in two‐dimensional materials. Recently, wavefront dislocations, a new feature of Friedel oscillations, have been revealed in graphene. However, previous analytical works have been limited to the linear dispersion of graphene. In this study, the fate of wavefront dislocations is investigated numerically in Friedel oscillations beyond the linear regime. The wavefront dislocations are robust against the trigonal warping effect, crucial for high doping graphene, due to the invariant winding number of the tight‐binding energy band. Furthermore, the opening of the gap, increasing the electronic Fermi wavelength, can highlight the wavefront dislocations blurred by intravalley scattering induced short‐range oscillations. These results should be observable using current experimental technology. Therefore, this study not only demonstrates the robust existence of wavefront dislocations in Friedel oscillations over a wide range of energies but also deepens the understanding of intervalley scattering in graphene and other two‐dimensional valleytronic materials.This article is protected by copyright. All rights reserved.
{"title":"Wavefronts Dislocations of Friedel Oscillations in Graphene: Trigonal Warping Effect","authors":"Jin Yang, Shu-Hui Zhang, Wen Yang","doi":"10.1002/pssr.202300378","DOIUrl":"https://doi.org/10.1002/pssr.202300378","url":null,"abstract":"The electron waves of a host system exhibit an oscillating response to an external impurity, namely Friedel oscillations, extensively studied in two‐dimensional materials. Recently, wavefront dislocations, a new feature of Friedel oscillations, have been revealed in graphene. However, previous analytical works have been limited to the linear dispersion of graphene. In this study, the fate of wavefront dislocations is investigated numerically in Friedel oscillations beyond the linear regime. The wavefront dislocations are robust against the trigonal warping effect, crucial for high doping graphene, due to the invariant winding number of the tight‐binding energy band. Furthermore, the opening of the gap, increasing the electronic Fermi wavelength, can highlight the wavefront dislocations blurred by intravalley scattering induced short‐range oscillations. These results should be observable using current experimental technology. Therefore, this study not only demonstrates the robust existence of wavefront dislocations in Friedel oscillations over a wide range of energies but also deepens the understanding of intervalley scattering in graphene and other two‐dimensional valleytronic materials.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138967221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Ishii, Midori Umakoshi, Kenta Kobayashi, Runa Kato, A. Al-Zubaidi, Shinji Kawasaki
We propose a new energy cycle called the “HI cycle” that involves the repeated generation of solar hydrogen and battery power. Solar hydrogen generation using an HI solution allows for the use of a narrower band gap photocatalyst compared to water. We demonstrated that the addition of single‐walled carbon nanotubes (SWCNTs) effectively enhances solar hydrogen generation from an HI solution with methylammonium lead iodide (MAPbI3). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, along with energy‐dispersive X‐ray spectroscopy (EDS) analysis and Raman measurements, revealed that SWCNTs improve hydrogen generation by adsorbing by‐product iodine molecules. We also fabricated a zinc‐iodine battery using the paper form of I@SWCNTs recovered from the photocatalyst test cell and zinc metal. We demonstrated that the battery efficiently operated with an initial cell voltage of approximately 1.2 V. The battery’s capacity, corresponding to the amount of encapsulated iodine molecules, indicated that SWCNTs can effectively adsorb the by‐product iodine molecules within the photocatalyst test cell. We also discussed that the electrolyte solution after the discharge experiment should include not only iodide ions but also a significant amount of hydrogen ions, indicating that the solution after battery discharge returns to the starting point of the “HI cycle.” Raman measurements revealed that I@SWCNTs, formed during the solar hydrogen generation experiment, were transformed back into empty tubes during the discharge experiment. Therefore, SWCNTs can be repeatedly used in the new cyclic energy scheme referred to as the “HI cycle.”This article is protected by copyright. All rights reserved.
{"title":"Hydrogen iodide energy cycle to repeat solar hydrogen generation and battery power generation using single‐walled carbon nanotubes","authors":"Y. Ishii, Midori Umakoshi, Kenta Kobayashi, Runa Kato, A. Al-Zubaidi, Shinji Kawasaki","doi":"10.1002/pssr.202300236","DOIUrl":"https://doi.org/10.1002/pssr.202300236","url":null,"abstract":"We propose a new energy cycle called the “HI cycle” that involves the repeated generation of solar hydrogen and battery power. Solar hydrogen generation using an HI solution allows for the use of a narrower band gap photocatalyst compared to water. We demonstrated that the addition of single‐walled carbon nanotubes (SWCNTs) effectively enhances solar hydrogen generation from an HI solution with methylammonium lead iodide (MAPbI3). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations, along with energy‐dispersive X‐ray spectroscopy (EDS) analysis and Raman measurements, revealed that SWCNTs improve hydrogen generation by adsorbing by‐product iodine molecules. We also fabricated a zinc‐iodine battery using the paper form of I@SWCNTs recovered from the photocatalyst test cell and zinc metal. We demonstrated that the battery efficiently operated with an initial cell voltage of approximately 1.2 V. The battery’s capacity, corresponding to the amount of encapsulated iodine molecules, indicated that SWCNTs can effectively adsorb the by‐product iodine molecules within the photocatalyst test cell. We also discussed that the electrolyte solution after the discharge experiment should include not only iodide ions but also a significant amount of hydrogen ions, indicating that the solution after battery discharge returns to the starting point of the “HI cycle.” Raman measurements revealed that I@SWCNTs, formed during the solar hydrogen generation experiment, were transformed back into empty tubes during the discharge experiment. Therefore, SWCNTs can be repeatedly used in the new cyclic energy scheme referred to as the “HI cycle.”This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91126352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haruto Hashimoto, Ryohei Oka, Tomokatsu Hayakawa, Christoph Brabec
In this study, lead‐free, mixed‐halide perovskites of cesium bismuth bromide/iodide are synthesized by a hydrothermal method, and their structures and optical properties of the solid solution compounds are examined. The synthesized compounds exhibit X‐ray diffraction (XRD) patterns similar to that of trigonal Cs3Bi2Br9 (CBB), whose reflections are shifted to lower angles depending on the experimental iodine content. Very interestingly, even with the excessive introduction of iodine content in nominal, the symmetry of the crystals is kept to be trigonal, indicating that bromide CBB and iodide Cs3Bi2I9 (CBI) are crystallographically mixed in a facile way, although the stable crystal form of CBI is hexagonal. The optical properties of bandgap energy E g and photoluminescence (PL) for the synthesized crystals are also examined. It is found that E g decreases and PL peak position is correspondingly shifted to a longer wavelength with an increase in the experimental iodine content due to their band‐to‐band transitions. Moreover, first‐principles calculation suggests the reduction of E g with iodine content and the varied nature of band structure from direct (trigonal CBB) to indirect (trigonal CBI) transition. These novel findings could make the proposed strategy successful for developing lead‐free, mixed‐halide Bi‐based perovskite crystals with the tunability of their optical properties.This article is protected by copyright. All rights reserved.
{"title":"Bandgap and photoluminescence tunability of lead‐free Cs3Bi2(Br,I)9 solid solution compounds","authors":"Haruto Hashimoto, Ryohei Oka, Tomokatsu Hayakawa, Christoph Brabec","doi":"10.1002/pssr.202300241","DOIUrl":"https://doi.org/10.1002/pssr.202300241","url":null,"abstract":"In this study, lead‐free, mixed‐halide perovskites of cesium bismuth bromide/iodide are synthesized by a hydrothermal method, and their structures and optical properties of the solid solution compounds are examined. The synthesized compounds exhibit X‐ray diffraction (XRD) patterns similar to that of trigonal Cs3Bi2Br9 (CBB), whose reflections are shifted to lower angles depending on the experimental iodine content. Very interestingly, even with the excessive introduction of iodine content in nominal, the symmetry of the crystals is kept to be trigonal, indicating that bromide CBB and iodide Cs3Bi2I9 (CBI) are crystallographically mixed in a facile way, although the stable crystal form of CBI is hexagonal. The optical properties of bandgap energy E\u0000g\u0000 and photoluminescence (PL) for the synthesized crystals are also examined. It is found that E\u0000g\u0000 decreases and PL peak position is correspondingly shifted to a longer wavelength with an increase in the experimental iodine content due to their band‐to‐band transitions. Moreover, first‐principles calculation suggests the reduction of E\u0000g\u0000 with iodine content and the varied nature of band structure from direct (trigonal CBB) to indirect (trigonal CBI) transition. These novel findings could make the proposed strategy successful for developing lead‐free, mixed‐halide Bi‐based perovskite crystals with the tunability of their optical properties.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"88 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81958117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Otsuka, Ryohei Oka, Masayuki Karasuyama, Tomokatsu Hayakawa
Currently, data‐driven approaches for exploring novel materials are garnering significant attention with the expectation of accelerating material development cycles and understanding materials from various aspects. This short article presents a supervised prediction model for the emission intensity ratio of 5D0–7F2 and 5D0–7F1 transition of Eu3+ ions, called an “asymmetry ratio,” which determines the color purity of the red region of Eu3+ photoluminescence in perovskite phosphors. The model is developed using a dataset of 296 samples and 203 descriptors for Eu3+‐doped perovskite. The accuracy of the prediction model trained by the dataset is statistically evaluated, which validates its sufficiently high prediction performance. Furthermore, the prediction model’s performance is properly assessed by synthesizing a Eu3+‐doped NaLaInNbO6 compound, which is unknown as a red phosphor, and by comparing the experimental asymmetry ratio for this compound with that predicted by the predictor, which exhibits a satisfactory agreement.This article is protected by copyright. All rights reserved.
{"title":"Photoluminescence Color Prediction for Eu3+‐doped Perovskite Red Phosphors using Machine Learning","authors":"T. Otsuka, Ryohei Oka, Masayuki Karasuyama, Tomokatsu Hayakawa","doi":"10.1002/pssr.202300237","DOIUrl":"https://doi.org/10.1002/pssr.202300237","url":null,"abstract":"Currently, data‐driven approaches for exploring novel materials are garnering significant attention with the expectation of accelerating material development cycles and understanding materials from various aspects. This short article presents a supervised prediction model for the emission intensity ratio of 5D0–7F2 and 5D0–7F1 transition of Eu3+ ions, called an “asymmetry ratio,” which determines the color purity of the red region of Eu3+ photoluminescence in perovskite phosphors. The model is developed using a dataset of 296 samples and 203 descriptors for Eu3+‐doped perovskite. The accuracy of the prediction model trained by the dataset is statistically evaluated, which validates its sufficiently high prediction performance. Furthermore, the prediction model’s performance is properly assessed by synthesizing a Eu3+‐doped NaLaInNbO6 compound, which is unknown as a red phosphor, and by comparing the experimental asymmetry ratio for this compound with that predicted by the predictor, which exhibits a satisfactory agreement.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74956999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, high‐k dielectric behaviour of TeO2 thin films is investigated. The films are prepared using pulsed laser deposition on ITO‐glass substrates. Increasing the growth temperature has improved the surface roughness, transparency and band gap of the films. Films grown at 500 °C display nanocrystalline nature which is reflected in the increase of band gap to 4.7 eV and is higher than the bulk value of α‐TeO2 (3.7 eV). The nanocrystalline TeO2 films in the metal‐insulator‐metal configuration showed a stable high permittivity of ∽19 with low leakage current (J < 1×10−7 A cm−2) and good voltage stability (α= 509 ppm V−2). Field effect modulation is observed in the metal‐oxide‐semiconductor stack configuration with tellurium as a semiconductor. The study suggests, nanocrystalline TeO2 as a low temperature processable high‐k material with high transparency for transistor applications.This article is protected by copyright. All rights reserved.
{"title":"TeO2: A prospective high‐k dielectric","authors":"Keerthana, A. Venimadhav","doi":"10.1002/pssr.202300271","DOIUrl":"https://doi.org/10.1002/pssr.202300271","url":null,"abstract":"In this work, high‐k dielectric behaviour of TeO2 thin films is investigated. The films are prepared using pulsed laser deposition on ITO‐glass substrates. Increasing the growth temperature has improved the surface roughness, transparency and band gap of the films. Films grown at 500 °C display nanocrystalline nature which is reflected in the increase of band gap to 4.7 eV and is higher than the bulk value of α‐TeO2 (3.7 eV). The nanocrystalline TeO2 films in the metal‐insulator‐metal configuration showed a stable high permittivity of ∽19 with low leakage current (J < 1×10−7 A cm−2) and good voltage stability (α= 509 ppm V−2). Field effect modulation is observed in the metal‐oxide‐semiconductor stack configuration with tellurium as a semiconductor. The study suggests, nanocrystalline TeO2 as a low temperature processable high‐k material with high transparency for transistor applications.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":"127 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80960105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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