{"title":"Lanthanide Functionalized Hydrogen-bonded Organic Framework Hybrid Materials: Luminescence Responsive Sensing, Intelligent Applications and Biomimetic Design","authors":"Kai Zhu, Xin Xu, Bing Yan","doi":"10.1021/accountsmr.4c00218","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00218","url":null,"abstract":"As a distinct category of crystalline porous materials, hydrogen-bonded organic frameworks (HOFs) are assembled from organic building blocks through H-bonding and other weak intermolecular interactions, which position HOFs as a versatile platform for investigating multifunctional porous materials. Aromatic subunits existing in the majority of HOF linkers are responsible for the luminescence exhibited by HOFs upon ultraviolet excitation mostly in nature. Recently, there has been a surge of attention in utilizing luminescent functionalized HOFs for luminescence responsive sensing due to their strong fluorescence and phosphorescence emission, versatile postsynthetic functionalization property, great solution processing performance, outstanding luminescent stability and specific recognition ability, and excellent biocompatibility.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"68 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142159001","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}
Dong Zhang, Qiang Chen, Hong Chen, Yijing Tang, Jie Zheng
{"title":"Spontaneous Macrophase Separation Strategy for Bridging Hydrogels from Bilayer to Double-Network Structure","authors":"Dong Zhang, Qiang Chen, Hong Chen, Yijing Tang, Jie Zheng","doi":"10.1021/accountsmr.4c00209","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00209","url":null,"abstract":"Bilayer hydrogels and double-network (DN) hydrogels represent two distinct classes of soft-wet materials, each characterized by their distinctive network structures, design principles, synthesis methods, and core functions targeted for their specific applications. Bilayer hydrogels are structured in two different layers, each with their anisotropic structure and unique properties. This dual-layer configuration facilitates targeted responses or controlled actuation in response to environmental stimuli, making them ideal for applications requiring responsive material behavior. On the other hand, DN hydrogels consist of two interwoven yet independent networks: one brittle and the other elastic. This dual-network structure, featuring contrasting network properties, allows for substantial energy dissipation and mechanical enhancement, often far exceeding that of traditional single-network hydrogels. Despite the individual strengths and specialized applications of each hydrogel type, a unified fabrication strategy that addresses both types of hydrogels has been conspicuously missing due to their inherent structural differences. This gap in the hydrogel field presents significant challenges but also opens opportunities for innovation in material design and application.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130988","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}
Dong Zhang, Qiang Chen, Hong Chen, Yijing Tang and Jie Zheng*,
{"title":"Spontaneous Macrophase Separation Strategy for Bridging Hydrogels from Bilayer to Double-Network Structure","authors":"Dong Zhang, Qiang Chen, Hong Chen, Yijing Tang and Jie Zheng*, ","doi":"10.1021/accountsmr.4c0020910.1021/accountsmr.4c00209","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00209https://doi.org/10.1021/accountsmr.4c00209","url":null,"abstract":"<p >Bilayer hydrogels and double-network (DN) hydrogels represent two distinct classes of soft-wet materials, each characterized by their distinctive network structures, design principles, synthesis methods, and core functions targeted for their specific applications. Bilayer hydrogels are structured in two different layers, each with their anisotropic structure and unique properties. This dual-layer configuration facilitates targeted responses or controlled actuation in response to environmental stimuli, making them ideal for applications requiring responsive material behavior. On the other hand, DN hydrogels consist of two interwoven yet independent networks: one brittle and the other elastic. This dual-network structure, featuring contrasting network properties, allows for substantial energy dissipation and mechanical enhancement, often far exceeding that of traditional single-network hydrogels. Despite the individual strengths and specialized applications of each hydrogel type, a unified fabrication strategy that addresses both types of hydrogels has been conspicuously missing due to their inherent structural differences. This gap in the hydrogel field presents significant challenges but also opens opportunities for innovation in material design and application.</p><p >In this Account, we introduce a new macrophase separation strategy that leverages differential polymerization rates and sol-to-gel phase transitions, enabling a bridging of the design and manufacturing gap between bilayer and DN hydrogels. This strategy facilitates the smooth creation of hydrogels with varied structures, from bilayer to DN structures, enabling the precise control of topological networks and multiscale hierarchical architectures. The approach is grounded in the selection of polymer pairs that are compatible with the macrophase separation concept, ensuring that the distinct characteristics of both bilayer and DN hydrogels are effectively realized in terms of their structures, design strategies, synthesis routes, and primary functions. Three distinct macrophase separation strategies are outlined, each demonstrating the concept through the careful selection of compatible polymer pairs. By demonstrating the versatility and functionality of the bilayer and DN hydrogels, the macrophase separation strategy not only achieves rapid and reversible actuation in bilayer hydrogels and outstanding mechanical strength and interfacial adhesion in DN hydrogels but also combines dynamic actuation abilities with robust mechanical integrity within both bilayer and DN hydrogels.</p><p >The macrophase separation strategy surpasses conventional fabrication methods such as layer-by-layer 3D/4D printing, self-assembly, and composite integration, due to its straightforward preparation process, exceptional phase separation efficiency, improved control of layer thickness, and faster responsiveness. This strategy acts as a transformative approach for readily integrating multifunctional and ","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"5 11","pages":"1415–1427 1415–1427"},"PeriodicalIF":14.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691366","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}
Jisu Kwon, Yoonbin Shin, Yunmo Sung, Hyunmi Doh, Sungjee Kim
{"title":"Silver Sulfide Nanocrystals and Their Photodetector Applications","authors":"Jisu Kwon, Yoonbin Shin, Yunmo Sung, Hyunmi Doh, Sungjee Kim","doi":"10.1021/accountsmr.4c00109","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00109","url":null,"abstract":"Silver sulfide nanocrystals (Ag<sub>2</sub>S NCs) exhibit unique infrared (IR) absorption and emission capabilities, drawing great interest for their broad applicability. These NCs are considered environmentally friendly alternatives to heavy metals such as lead (Pb), mercury (Hg), and cadmium (Cd) chalcogenides. This Account provides a comprehensive overview based on our research on Ag<sub>2</sub>S NCs. We investigated their synthesis over size and shape, surface stoichiometry control, postsynthetic surface composition change, and optoelectronic application. The work began with developing a synthesis protocol for the Ag<sub>2</sub>S NCs. Size-tunable and nearly monodisperse NCs were obtained through the precise control of precursor ratio. The ability to manipulate the size of the NCs enabled us to explore and adjust their optical properties. Another important aspect of the research focused on the mechanism of shape transformation. The evolution of the NCs from their initial spherical structure to more complex shapes such as rods and cubes was observed. Through rigorous investigations using a transmission electron microscope (TEM), we studied the relationship between the morphological changes and crystal facets. Investigations were also extended to surface chemistry, where methods were developed to tune the surface stoichiometry of Ag<sub>2</sub>S NCs. Perfectly stoichiometric-surfaced Ag<sub>2</sub>S NCs synthesized through ion-pair ligand-assisted surface reactions exhibited significantly increased photoluminescence (PL) and an enhanced epitaxial ZnS growth rate. Finally, we explored the cation exchange reactions of Ag<sub>2</sub>S NCs. The cation exchange reaction with indium (In) ions yielded AgInS<sub>2</sub> NCs with size-dependent crystal structures: tetragonal for small NCs and orthorhombic for large NCs. A critical size at around 4.3 nm was observed, representing a trade-off between a thermodynamically more stable tetragonal structure and an orthorhombic structure that preserves the anionic framework. Throughout this Account, we address the challenges for the application of Ag<sub>2</sub>S NCs and propose future directions including advancements in synthesis techniques, surface chemistry, and their applications. Ag<sub>2</sub>S NCs typically show limitations such as low chemical and electrical stability, which may originate from the low lattice energy and high concentration of cation vacancies. However, such unique features can be advantageous for some applications, for example, acceptor materials in photomultiplication (PM)-type photodiodes. PM-type photodiodes were developed by combining polymeric semiconductors and Ag<sub>2</sub>S NCs. These photodiodes can amplify signals by trapping electrons within Ag<sub>2</sub>S NCs. These NCs efficiently trap multiple charge carriers from donor materials, in which their typical disadvantage is reinterpreted as a beneficial attribute for advanced device applications. In order to enhance the elect","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"100 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101859","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}
{"title":"Silver Sulfide Nanocrystals and Their Photodetector Applications","authors":"Jisu Kwon, Yoonbin Shin, Yunmo Sung, Hyunmi Doh and Sungjee Kim*, ","doi":"10.1021/accountsmr.4c0010910.1021/accountsmr.4c00109","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00109https://doi.org/10.1021/accountsmr.4c00109","url":null,"abstract":"<p >Silver sulfide nanocrystals (Ag<sub>2</sub>S NCs) exhibit unique infrared (IR) absorption and emission capabilities, drawing great interest for their broad applicability. These NCs are considered environmentally friendly alternatives to heavy metals such as lead (Pb), mercury (Hg), and cadmium (Cd) chalcogenides. This Account provides a comprehensive overview based on our research on Ag<sub>2</sub>S NCs. We investigated their synthesis over size and shape, surface stoichiometry control, postsynthetic surface composition change, and optoelectronic application. The work began with developing a synthesis protocol for the Ag<sub>2</sub>S NCs. Size-tunable and nearly monodisperse NCs were obtained through the precise control of precursor ratio. The ability to manipulate the size of the NCs enabled us to explore and adjust their optical properties. Another important aspect of the research focused on the mechanism of shape transformation. The evolution of the NCs from their initial spherical structure to more complex shapes such as rods and cubes was observed. Through rigorous investigations using a transmission electron microscope (TEM), we studied the relationship between the morphological changes and crystal facets. Investigations were also extended to surface chemistry, where methods were developed to tune the surface stoichiometry of Ag<sub>2</sub>S NCs. Perfectly stoichiometric-surfaced Ag<sub>2</sub>S NCs synthesized through ion-pair ligand-assisted surface reactions exhibited significantly increased photoluminescence (PL) and an enhanced epitaxial ZnS growth rate. Finally, we explored the cation exchange reactions of Ag<sub>2</sub>S NCs. The cation exchange reaction with indium (In) ions yielded AgInS<sub>2</sub> NCs with size-dependent crystal structures: tetragonal for small NCs and orthorhombic for large NCs. A critical size at around 4.3 nm was observed, representing a trade-off between a thermodynamically more stable tetragonal structure and an orthorhombic structure that preserves the anionic framework. Throughout this Account, we address the challenges for the application of Ag<sub>2</sub>S NCs and propose future directions including advancements in synthesis techniques, surface chemistry, and their applications. Ag<sub>2</sub>S NCs typically show limitations such as low chemical and electrical stability, which may originate from the low lattice energy and high concentration of cation vacancies. However, such unique features can be advantageous for some applications, for example, acceptor materials in photomultiplication (PM)-type photodiodes. PM-type photodiodes were developed by combining polymeric semiconductors and Ag<sub>2</sub>S NCs. These photodiodes can amplify signals by trapping electrons within Ag<sub>2</sub>S NCs. These NCs efficiently trap multiple charge carriers from donor materials, in which their typical disadvantage is reinterpreted as a beneficial attribute for advanced device applications. In order to enhance the","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"5 9","pages":"1097–1108 1097–1108"},"PeriodicalIF":14.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326277","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}
Hongwei Chen*, Chenji Hu, Xiaoqing Zhang and Liwei Chen*,
{"title":"Porous Crystalline Frameworks as Ion-Conducting Solid-State Electrolytes","authors":"Hongwei Chen*, Chenji Hu, Xiaoqing Zhang and Liwei Chen*, ","doi":"10.1021/accountsmr.4c0015610.1021/accountsmr.4c00156","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00156https://doi.org/10.1021/accountsmr.4c00156","url":null,"abstract":"<p >Room-temperature Li<sup>+</sup> conductors have been intensively revisited to develop high-safety solid-state batteries. While promising inorganic Li<sup>+</sup> solid-state electrolytes (SSEs) with competitive ionic conductivity have been demonstrated, their practical applications are still hindered by manufacturing technology, cost constraints, and internal battery interfaces. Advances in the design and synthesis of periodic frameworks over the past decade have created a new platform for designing SSEs. These porous crystalline frameworks feature open channels that can be tailored into ion-hopping sites and guest-accessible voids, both essential for SSE construction. Framework-based SSEs uniquely merge the advantages of inorganic crystal-like ordered structures and the design flexibility of organic molecules, distinguishing them significantly from traditional inorganic or organic SSEs. Enhancing ionic conduction and exploring potential applications are two critical factors driving the rapid advancement of framework-based SSEs.</p><p >In this account, we summarize recent progress in framework-based SSEs and discuss factors influencing ion pair dissociation and free ion diffusion within these frameworks. An appropriately charged framework and guest assistance are key factors in enhancing ionic conductivity. We also highlight the importance of maximizing void utilization in porous frameworks to optimize framework ion conductivity. In the latter part of this account, we delve into the practical potential of framework-based SSEs, considering that practicality is crucial for ensuring rapid development of such SSEs. We start by discussing the processability of these framework materials, including their fabrication into SSE membranes or integration into battery configurations for practical application. Enhancing interfacial contact of framework-based SSEs is crucial for eliminating interfacial impedance and improving mechanical properties. In the subsequent discussion, we propose frameworks not as replacements for current SSEs but as novel SSEs with unique functionalities that complement traditional SSEs for various applications. These functionalities include enhancing interface contact, suppressing side reactions, and promoting uniform lithium deposition, among others. Understanding their conductive mechanisms, developing practical fabrication methods, and exploring new functionalities are key to advancing framework-based SSEs.</p><p >We propose the following: (1) Enhancing the conductivity of future framework-based SSEs should focus on synergistic “ionic framework + guest assistance” conduction, aiming for optimized porous frameworks that provide adequate free ions, excellent ion mobility, and high void utilization. (2) One potential application of framework-based SSEs is utilization as functional additives, offering specific functionalities that traditional SSEs lack or are less proficient at. (3) Developing orderly assembled frameworks compatib","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"5 11","pages":"1303–1313 1303–1313"},"PeriodicalIF":14.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142691269","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}
Hohyung Kang, Ahyeon Cho, Seongcheol Park, Soo-Yeon Cho, Hee-Tae Jung
{"title":"Top-Down Fabrication of Chemical and Biological Sensors","authors":"Hohyung Kang, Ahyeon Cho, Seongcheol Park, Soo-Yeon Cho, Hee-Tae Jung","doi":"10.1021/accountsmr.4c00170","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00170","url":null,"abstract":"Fabrication of complex three-dimensional (3D) structures with micro/nanoscale dimensions is crucial for high-performing chemical and biological sensor applications. It not only enables the accurate detection and tracking of minuscule chemical and biological analytes but also determines the commercial viability and practical utilization of the sensors in future intricate applications. Among various structure fabrication approaches, top-down lithography provides invaluable tools for fabricating complex 3D micro/nanoscale structures in sensors, enabling the sensitive and selective detection of low concentration chemical and biological analytes. Moreover, it preserves the inherent advantages of top-down lithography as the sensor attributes, including (i) high-resolution and tight pitch 3D structures in long-range order, (ii) varied pattern shapes, dimensions, and densities, (iii) low device-to-device variation, (iv) high integrated circuit yield, (v) acceptable process cost and processability, and (vi) the ability to accommodate a wide range of materials. Given the variety of top-down lithographic methods available for fabricating sensors and the complex requirements of the sensor such as diverse target analytes, varying concentration levels, and different sensing environments, it is essential to have a comprehensive understanding of the technical nuances associated with each top-down lithography technique and its applications. However, there is a significant gap in the literature regarding targeted evaluations of top-down lithography methods for high-performance chemical and biological sensor fabrication as well as a clear articulation of sensor design rules.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178207","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}
{"title":"Porous Crystalline Frameworks as Ion-Conducting Solid-State Electrolytes","authors":"Hongwei Chen, Chenji Hu, Xiaoqing Zhang, Liwei Chen","doi":"10.1021/accountsmr.4c00156","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00156","url":null,"abstract":"Room-temperature Li<sup>+</sup> conductors have been intensively revisited to develop high-safety solid-state batteries. While promising inorganic Li<sup>+</sup> solid-state electrolytes (SSEs) with competitive ionic conductivity have been demonstrated, their practical applications are still hindered by manufacturing technology, cost constraints, and internal battery interfaces. Advances in the design and synthesis of periodic frameworks over the past decade have created a new platform for designing SSEs. These porous crystalline frameworks feature open channels that can be tailored into ion-hopping sites and guest-accessible voids, both essential for SSE construction. Framework-based SSEs uniquely merge the advantages of inorganic crystal-like ordered structures and the design flexibility of organic molecules, distinguishing them significantly from traditional inorganic or organic SSEs. Enhancing ionic conduction and exploring potential applications are two critical factors driving the rapid advancement of framework-based SSEs.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178232","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}
{"title":"Functional Covalent Organic Frameworks: Design Principles to Potential Applications","authors":"Yusran Yusran, Bo Miao, Shilun Qiu, Qianrong Fang","doi":"10.1021/accountsmr.4c00195","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00195","url":null,"abstract":"Covalent organic frameworks (COFs) represent an emerging class of crystalline porous polymers synthesized by linking predesigned organic building units into targeted repetitive networks. The unique features of COFs stem from their modular synthesis, allowing for precise control over the chemical composition and functionalization on both the skeleton and the pore walls. Topologically, COFs are defined not by their chemical nature but by the symmetry and dimensions of the building units, resulting in 2D and 3D structures with distinct surface areas, pore architectures, and arrangements of functional moieties. The combination of predesigned organic units into geometries results in frameworks that can be precisely controlled and modified. This control is vital for applications requiring materials with specific pore sizes, surface areas, and functional group distributions. Particularly, COFs show great potential in the field of gas storage and separation, energy storage and conversion, catalysis, sensing, environmental remediation, and many more. Hence, an effective designed approach to incorporate various functional properties into the structures is pivotal to manipulate the functional properties and potential applications of COFs.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178234","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}
{"title":"Electrically Stable Self-Assembled Monolayers Achieved through Repeated Surface Exchange of Molecules","authors":"Jiung Jang, Gyu Don Kong, Hyo Jae Yoon","doi":"10.1021/accountsmr.4c00190","DOIUrl":"https://doi.org/10.1021/accountsmr.4c00190","url":null,"abstract":"Self-assembled monolayers (SAMs) are two-dimensional molecular ensembles. In molecular electronics, SAMs serve as active components for exploring structure-tunneling relationships due to their easy and simple fabrication and atomic-detailed (supra)molecular modifications. Single-component pure SAMs are commonly incorporated into tunneling junctions. However, pure SAMs are defective to some extent, which results in low electrical breakdown voltages and allows access to narrow bias windows through the junctions. Narrow bias windows ultimately limit the possible charge-transport channels to shallow molecular orbital energy levels such as the highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO), making it difficult to investigate charge transport through deeper molecular orbital (MO) energy levels such as sub-HOMOs and post-LUMOs.","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142043308","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}