Various phases from the self-assembly of block copolymer (BCP) as the outcome of microphase separation thermodynamically have been studied for decades. This review proposed a facile approach for creating metastable network phases with triply periodic minimal surface (TPMS) by using selective solvent with controlled evaporation for casting. The combination of BCP/solvent equilibrium state and kinetic control for solvent evaporation offers the opportunity to capture the local minimum metastable states with high packing frustration, giving the formation of double primitive and double diamond as well as double gyroid phases from controlled self-assembly of high-$\chi$ BCPs. The controlled windows for those network phases can be further expanded by using star-block copolymers due to the topological effect on self-assembly.

Designing conformationally dynamic molecules that self-assemble into predictable nanostructures remains a significant unmet challenge. This work describes the application of atomic-scale cryogenic transmission electron microscopy (cryo-TEM) to elucidate the relationship between molecular structure and self-assembly of block copolymers. Cryo-TEM images revealed the presence of atomic-scale corrugations in sheet-like micelles that are not anticipated by theories which assume that the surfaces of micelles are smooth. The authors propose that the atomic-scale corrugations are due to the dipolar nature of the monomers and interactions between the monomers and water molecules.

Unlocking complex nanostructures like triply periodic minimal surfaces in block copolymer systems poses a crucial hurdle in creating multiscale functional materials. Despite ingenious methods such as interface manipulation, introduction of conformational asymmetry, and chain connectivity regulation, achieving block copolymer self-assembly into nanostructures with high packing frustration remains elusive. In this research update, the authors spotlight the use of end-group chemistry as an effective strategy for stabilizing diverse complex network morphologies beyond the gyroid. Particularly, they redefine phase diagrams by introducing robust end-to-end interactions through end-group and linker chemistry, unveiling unprecedented network structures.

Mesoatoms, micelle-like supramolecular clusters, play a crucial role as intermediate building blocks in the formation of self-assembled superlattices. This Research Update highlights giant molecules (GMs) for their precision at the molecular level, enabling a focused examination of mesoatomic characteristics. It systematically explores practical guidelines in molecular design, with the goal of achieving controlled fabrication of molecule-based superlattices. The categorization of phases based on structural features, ranging from simple spherical packing to quasicrystalline and crystalline arrangements, allows the unraveling of tunable mesoatomic traits like individual size, size difference, stoichiometry, and shape distributions. These traits emerge as pivotal considerations in the strategic design of spherical superlattice phases.

Blending block copolymers with homopolymers and other block copolymers provides control over self-assembly kinetics, and unlocks a diversity of non-native morphologies. The authors review this emerging paradigm, focusing on the thin film regime, providing examples of enhanced ordering kinetics, control of morphology orientation, and even the formation of non-native structures that do not appear in the bulk equilibrium phase diagram.

Close-packed structures of spherical particles describe the ordered lattices of many systems, such as oranges stacked on grocery stands, densely packed colloids, and solid elements. However, stabilizing a target close-packed structure of a material system has been a puzzling problem. This research update overviews the early and recent progress on the close-packed structures in block copolymer materials and attempts to identify the unrealized role of polymer chains as a structure director in polytypic crystal systems. The polymer chains stabilize polytypes with larger local interstitial space groups, allowing higher conformational entropy of the chains.

Recent milestones in the synthesis and characterization of polar metals have contributed to a rapidly growing field of research, rich in materials physics and potential applications. The burgeoning interest, however, has been accompanied by varied and sometimes inconsistent terminology, inhibiting clear communication and revealing fundamental tensions between theoretical descriptions and microscopic materials models. The authors review the frontier of polar metals research from the perspectives of theory, experiment, and simulation, and introduce a uniform taxonomy for the classification of materials combining broken inversion symmetry and metallic conductivity. The authors use the framework to establish a new database of such materials and highlight opportunities for the discovery of novel polar metals.

Radiative cooling is a passive cooling technique that can send thermal energy into the frigid outer space. Recent research has demonstrated that it is possible to achieve an electricity-free subambient cooling effect during the daytime, which is attracting emerging interest within the field of energy sustainability. Here the authors provide a review of the state-of-art research in this topic. The fundamental principles and the general criteria of radiative cooling are discussed. Additionally, the research progress in developing high performance radiative cooling materials, system design, and applications is also summarized, providing the most up-to-date perspective on this active research area.

The development of high-entropy materials has, by virtue of the inherent complexity and sublattice disorder in such systems, unlocked a plethora of unique and tunable property spaces of interest across a wide range of applications. As a result, understanding structure-property relationships in these systems has become an area of interest within materials research, with particular emphasis on the transition to the unique disordered single-phase structure. This work reviews recent progress on studies of phase transition behavior in high-entropy oxides, with a particular focus on the role of entropy-stabilization in these complex systems.

The studies of Ni-rich cathode materials have been the top priority of research because of the high energy density and fair cycling life. However, suffering from severe crack generations and side reactions, the traditional polycrystal (PC) Ni-rich material displayed structural/electrochemical fade during cycling. Compared with PC, single-crystal (SC) Ni-rich materials exhibited excellent structural stability and cycling performance, benefiting from the limited side reaction and gas generation. In this review, the authors not only compared the structural evolution and electrochemical failure mechanisms between PC and SC, but also summarized the synthesis methods and characterization techniques of SC, which provides universal insights into the development of Ni-rich cathode materials.

Alkali metal ion batteries, and in particular Li-ion batteries, have become a key technology for current and future energy storage. The inherent complexity of batteries and their components make computational approaches on different length and time scales indispensable for gaining atomistic insights as well as for predicting new materials with improved properties. In this comprehensive review, the theoretical concepts that underlie the functioning of Li- and post-Li-ion batteries are presented, followed by a discussion of the most prominent computational methods and their applications, currently available for the investigation of battery materials on the atomistic scale.

Electronic structure simulations enable the calculation of a wide variety of fundamental materials properties. However, they consume a significant portion of scientific HPC resources worldwide. Artificial intelligence and machine learning, which have emerged as a powerful tool for analyzing complex datasets, have the potential to accelerate electronic structure calculations such as density functional theory. The combination of these two fields enables highly efficient simulations at unprecedented scales. In this review, the authors present a comprehensive analysis of research articles in chemistry and materials science that employ machine-learning techniques and outline the current trends at the intersection of these fields.

Introducing magnetism into topological insulators is critical for realizing exciting quantum transport effects. Higher magnetic ordering temperatures are urgently needed, ideally without increased defect levels in the materials. While both intrinsic magnetic topological insulators and those synthesized through magnetic doping have been highly successful at low-temperatures, magnetic proximity effects are viewed as a potential route towards higher temperature quantum transport. In this research update, the authors highlight recent approaches in introducing magnetic order in topological insulators through interfacing with various magnetic materials, focusing particularly on techniques for characterizing magnetic proximity effects and their applications in (Bi,Sb)${}_2$(Se,Te)${}_3$ based systems.

Metallic glasses that combine the mechanical properties of metals with the chemical durability of glasses are highly desirable, especially for applications in extreme environments such as those in nuclear and aerospace industries. However, commonly studied metallic glasses often crystallize at lower temperatures and are not suitable for such applications. In this research update, the authors highlight recent advances in metallic glasses with crystallization temperatures above 700˚C. These high temperature metallic glasses are discussed in terms of the formation methods, the glass forming ability, as well as the thermodynamic properties and mechanical properties. An outlook section provides the reader with an overview of the areas of research that have thus far been neglected with a specific focus on corrosion and mechanical properties. Successful development of high temperature metallic glasses can lead to a new class of materials for extreme environments.

The pyrochlore lattice is the arrangement of corner sharing tetrahedra, the well-known host of a wide range of exotic phenomena driven by magnetic frustration. Until recently, much of the work in this domain was confined to the oxide pyrochlore family of materials. Recent advancements are bringing the same research focus to several new families of materials where halide or chalcogenide anions replace oxygen. Each of these new families opens up new avenues of research such as allowing new magnetic ions, modifications to the local spin anisotropies, and a re-organization of the magnetic energy scales. In this research update, the authors highlight how these effects have opened new pathways for frustrated magnetism research, with an emphasis on future prospects.

Fluorine is the most electronegative element and its small size and highly polar bonding enable it to play a unique and vital role in many materials. In this Research Update, the authors review the potential for fluorine, when incorporated at interfaces, to address fundamental materials challenges to the stability and photophysical properties of halide perovskites, a burgeoning class of photovoltaic absorber materials. While the halide perovskite electronic structure is considered to be defect-tolerant in the bulk, defects at surfaces and grain boundaries are sites of carrier recombination and phase degradation due to their greater reactivity towards moisture and oxygen. Fluoride and fluorocarbons can directly prevent defects by increasing the bonding strength at grain boundaries as well as by acting as a hydrophobic physicochemical barrier. Less direct benefits are also discussed, such as morphological and cell band alignment improvements. Our discussion covers partial incorporation in the perovskite lattice of fluoride as a halide substitution and substitution of the native cations for fluorocarbon cations, as well as the inclusion of molecular fluorocarbons.

The possibility of imaging the internal chemical structure of molecular species is an ongoing challenge. Enormous strides to address this challenge have recently been made using the frequency-modulation mode of noncontact atomic force microscopy (nc-AFM), which is one of the most successful scanning probe microscopies. While experimental advances make it possible to observe the subatomic structure of a chemical species, the concurrent theoretical understanding of such imaging techniques remains problematic. Interpretation of nc-AFM images is not straightforward. The analysis of an image can be time consuming and can vary from worker to worker. In our Research Update, we address the role of replicating forces on the probe tip to simulate nc-AFM images, which is a difficult computational problem. We examine several computational approaches and illustrate how recent algorithmic developments can produce reliable images. We also suggest new pathways to overcome remaining obstacles in this rapidly evolving field.

The controlled modification of graphene’s electronic structure through chemical doping is a promising way to expand its possible applications. It is also a subject of interest for fundamental research as the effects of the dopants on the electronic structure of a two-dimensional (2D) material differ vastly from chemical doping of conventional 3D semiconductors such as silicon. In this research update, the authors describe the main results obtained so far on the modification of the electronic properties of graphene upon chemical doping. This includes the atomic scale characterization of the dopant configuration and charge distribution as probed by scanning tunneling microscopy and spectroscopy, momentum-resolved band structure modification as probed by angle-resolved photoemission spectroscopy, and detailed scattering mechanisms information obtained from magnetoresistance measurements. They give an exhaustive and critical account of the above-mentioned subjects, describe open questions, and suggest future research directions.

Chalcopyrite materials, like CuInSe2 or Cu(In,Ga)Se2, are used as absorbers in thin film solar cells. The interest in thin film solar cells is based on the fact that they present a particularly low carbon footprint. However, much less is known about the electronic defects in the material compared to more common semiconductors. The authors use mainly photoluminescence to study the electronic defects. In this paper they review experimental and theoretical defect studies and arrive at a comprehensive model. They show that the shallow defects, that contribute free carriers, can be identified from low temperature photoluminescence spectroscopy. Deep defects, which are detrimental to the solar cell, are also known to exist and are observed in capacitance spectroscopy but are difficult to observe in photoluminescence. The authors demonstrate that by a careful investigation of the composition dependence and the temperature dependence of the luminescence spectra, they can actually identify two deep defects in Cu(In,Ga)Se2: one is at least partly responsible for the efficiency loss of wide bandgap chalcopyrite solar cells, the other one could be responsible for the lower efficiency of Cu-rich material.

High entropy alloys (HEAs) have recently emerged as a new class of materials. Solids made from multiple transition metal elements, typically five or more, in equimolar or near equimolar ratios, they are stabilized by entropic contributions to the free energy. 3d-element-based HEAs have been widely studied in materials science. In addition to their promising mechanical properties, some HEAs have been reported to display superconductivity; these materials are largely based on 4d and 5d metals. In this update, we focus on the variations of HEA superconductors presently known and the progress made in studies of their properties, especially highlighting fundamental issues related to their superconducting transition temperatures. Some of the key factors that influence their characteristics include crystal structure, atomic makeup, valence electron count, molar volume and mixing entropy - all of these factors appearing to be influential in spite of the fact that the materials are most like metallic glasses on simple periodic lattices. Many opportunities and challenges remain for expanding our knowledge of HEA superconductors, finding new types of HEA superconductors, and their potential for applications.

III-V semiconductors are one of the most celebrated class of materials in solid-state physics and device technologies, and are obliquities in modern information technology, solid-state lighting, electronic and optoelectronic devices. However, there is a widespread realization today that several important technologies of the modern era such as thermoelectricity that converts waste heat into electrical energy, plasmonic materials and devices that could be utilized to harvest optical energy in solar-photovoltaics, solar-thermophotovoltaics, photocatalysis, metal/semiconductor superlattices etc. require materials and heterostructure metamaterials that are not possible to achieve with traditional III-V semiconductors. Scandium nitride (ScN) is a group 3 rocksalt indirect bandgap semiconductor and can overcome some of the limitations of traditional III-V semiconductors, thus leading to novel device functionalities. However, unlike other well-known III-V semiconductors, very little attention has been devoted to understand and engineer physical properties of ScN until very recently. In this research update, the authors detail the progress that has taken place over the last several years to overcome the material engineering challenges for high-quality epitaxial ScN thin film growth, analysis of its physical properties including in thermoelectricity and solid-state lighting, $n$-to-$p$ carrier-type transition, and epitaxial integration of ScN with other rocksalt metallic nitrides.

Cadmium arsenide is a time-honored material within condensed matter physics, with the first investigations dating back to the thirties. Nowadays, after theorists predicted a pair of symmetry-protected three-dimensional Dirac cones in its band structure, cadmium arsenide is going through an intense revival. Cadmium arsenide is now thought of as a three-dimensional analogue of graphene. Several experimental studies showed compelling evidence of conical bands in this material, revealing a number of interesting properties and phenomena. To interpret them correctly, a detailed understanding of the basic material parameters has become even more important than before. To this end, the authors extensively review the past and current knowledge of cadmium arsenide. They start with the crystal lattice properties, and continue with the technological aspects of its crystal growth. This is followed by a discussion of the theoretical and experimental results, leading to different possible views of this material’s electronic bands.

Much is being currently written about machine learning applied to materials science, but, what is machine learning? It is certainly not physics, chemistry, or materials science, in which case how do these sciences enter? In this Research Update the authors examine what machine learning is and is not, review several applications of machine learning methods for predicting new materials, noting some of the cases where the predictions have been experimentally validated, and illustrate the spectrum of applications possible. The emphasis is on the broader picture where they discuss some newer methods and more importantly reference their successes. Thus, the paper looks more towards the future than to the past, sharing some of the lessons the authors have learned from their own experience in the field.