Rutile titanium dioxide (TiO2) is regarded as one of the most promising electrode candidates for various rechargeable ion batteries applied in large-scale energy storage systems (ESSs) and electronic vehicles (EVs) due to its great cycling stability, high safety, and natural abundance. However, its poor electronic and ionic conductivities are the biggest obstacles on the way towards practical applications. In the past decades, four mainstream optimizing strategies were proposed to alleviate this issue, including constructing nanostructures, compositing with highly conductive materials, creating dual-phase interfaces, and introducing defects. Based on these strategies, a large number of rutile TiO2-based electrode materials were developed and gained good electrochemical performance for various rechargeable ion batteries. In this review, we retrospect the development pathway of TiO2-based electrode materials from the theoretical studies at the very beginning to today’s prosperity in material diversity. With a unique chronological perspective, the general and detailed evolution trends of rutile TiO2 electrode materials with different optimizing strategies are summarized. It is expected that this review can provide not only a complete overview of the development history of rutile TiO2 electrode materials but also a spotlight for the future trends of this promising electrode material towards practical applications.

Effective modifications for the buried interface between self-assembled monolayers (SAMs) and perovskites are vital for the development of efficient, stable inverted perovskite solar cells (PSCs) and their tandem photovoltaics. Herein, an ionic-liquid-SAM hybrid strategy is developed to synergistically optimize the uniformity of SAMs and the crystallization of perovskites above. Specifically, an ionic liquid of 1-butyl-3-methyl-1H-imidazol-3-iumbis((trifluoromethyl)sulfonyl)amide (BMIMTFSI) is incorporated into the SAM solution, enabling reduced surface roughness, improved wettability, and a more evenly distributed surface potential of the SAM film. Leveraging this optimized substrate, a favorable growth of high-quality perovskite crystals is achieved. Furthermore, the introduced functional ions readily bond with the perovskites, effectively passivating undesirable cation or halide vacancies of the perovskite near the buried interface. Remarkably, high power conversion efficiencies (PCEs) of 25.68% and 22.53% are obtained for normal-bandgap (≈1.55 eV) and wide-bandgap (WBG) (≈1.66 eV) PSCs along with improved operational stability. Additionally, a champion PCE of 19.50% is achieved for semitransparent WBG PSCs, further delivering an impressive PCE of 28.34% for integrated four-terminal tandem photovoltaics when combined with CuInGaSe2 solar cells.

Poly(N-isopropylacrylamide) (PNIPAM) is known for exhibiting lower critical solution temperature behavior in water. A structural isomer of PNIPAM, the likewise LCST-type polymer poly(N-vinylisobutyramide) (PNVIBAM), is compared to PNIPAM in a thin film with respect to their swelling behaviors and water uptake kinetics in a humid atmosphere. Based on spectral reflectance, Fourier-transform infrared (FT-IR) spectroscopy, and time-of-flight neutron reflectometry, the amount and kinetics of uptaken water and its distribution inside the films correlate with molecular changes. It is observed that PNVIBAM swells less than PNIPAM. The FT-IR signals reveal a lower water affinity for PNVIBAM than for PNIPAM and larger hydrophobic clathrates in PNVIBAM, which hinders the introduction of water. Additionally, N2-dried PNIPAM films still contain primary water, whereas PNVIBAM can be fully dried. The first step of water uptake of the main layer describes a filling of the free volume, reaching a water content of 3.8% in PNVIBAM and 6% in PNIPAM.

Solid additives have garnered significant attention due to their numerous advantages over liquid additives. This study explores the potential of the green-fluorescent conjugated polymer denoted Atums Green as a solid additive in green-solvent-based PBDB-TF-T1:BTP-4F-12 solar cells. Even tiny amounts of Atums Green doping significantly improve the device performance. For the reference solar cell without any additive, we find that device degradation is not caused by chemical redox reactions but by changes in crystallinity and microstructure evolution during aging in air under illumination. Operando GIWAXS and GISAXS are used to investigate the structure evolution. We discover a four-stage degradation process for the reference cell. In general, the lattice spacing and crystallite coherence length decrease, while the domain sizes increase, which causes the loss of shirt-circuit current J SC and fill factor FF. Furthermore, a decomposition component is detected in GIWAXS and GISAXS, corresponding to the loss of the open-circuit voltage V OC. Atums Green doping effectively suppresses the evolution of crystallinity and domain sizes as well as the continuous decomposition, thereby enhancing the device stability under illumination in air. This finding reveals the kinetic degradation process of organic solar cells, establishes a correlation between the morphological properties and device performance, and further demonstrates the promising potential of Atums Green doping in organic solar cells.

The early stages of crystallization and occurrence of surface wrinkling were investigated using poly(butadiene)-block-poly(ε-caprolactone) with an ordered lamellar structure. Direct evidence has demonstrated that surface wrinkling precedes nucleation and crystal growth. This study examined the relationship between surface wrinkling, nucleation, and the formation of crystalline supramolecular structures using atomic force microscopy (AFM) and X-ray scattering measurements. Surface wrinkling is attributed to curving induced by accumulated stresses, including residual stress from the sample preparation and thermal stress during cooling. These stresses cause large-scale material flow and corresponding changes in the molecular conformations, potentially reducing the nucleation barrier. This hypothesis is supported by the rapid crystal growth observed following the spread of surface wrinkles. Additionally, the surface curving of the polymer thin film creates local minima of the free energy, facilitating nucleation. The nuclei subsequently grow into crystalline supramolecular structures by incorporating polymer molecules from the melt. This mechanism highlights the role of localized structural inhomogeneity in the early stages of crystallization and provides new insights into structure formation processes.

A wearable detector to monitor visible light intensity is realized by the restrained photochromism of a hydrogel composite containing light-responsive spiropyran with hydroxyl groups (SPOH). When exposed to visible light, the SPOH experiences a ring-opening to a ring-closed transition accompanied by discoloration from red to yellow. Unlike in the solution, the photochromism/discoloration rate is strongly correlated to the cross-linking points. By reducing the amount of cross-linker from 40 to 5 mg, the photochromism rate of SPOH is 300% faster. Inspired by the Chinese Jade Loong from Hongshan, the hydrogel composite is shaped into a Loong to monitor the light intensity. By increasing the amount of cross-linker in the head, body, and tail, the photochromism/discoloration rate sequentially turns slower from one region to the other. Higher light intensity is required to realize the discoloration in the hydrogel composite containing a larger amount of the cross-linker. Because the initial colors are identical, the light intensity can be easily traced by checking the discoloration of these pieces containing different amounts of cross-linker. Based on this unique and reversible photochromic capability, the present hydrogel composite can be used for monitoring the visible light intensity to prevent myopia, especially for children and students.

PbS quantum dots (QDs) are promising materials for low-cost short-wave infrared (SWIR) photodetection and imaging applications, owing to their unique optical properties and tunable bandgap. High-performance photodiodes rely on thiol-treated small PbS QDs as the hole transport layer (HTL) due to their suitable band alignment, but they face challenges such as crack formation, which increases dark currents. We develop a crack-free HTL by mixing small-size and large-size QDs. Grazing incidence small-angle X-ray scattering data confirms that the hybrid-size QD HTL is more homogeneous and denser than that made from monosize QDs. Photophysical studies show optimized charge carrier dynamics and energy transfer in the hybrid-size QDs, compared to monosize QDs. The devices based on the hybrid-size QD HTL exhibit a significantly reduced dark current density (392 nA/cm2). Additionally, they show high device performance, including a responsivity of 0.65 A/W, detectivity of 2.4 x 1012 Jones, and an external quantum efficiency of 65% in the SWIR region, paving the way for high-performance QD-based SWIR photodetectors.

Polymer nanocomposites (PNCs), which feature a hybrid network of soft polymers filled with nanoparticles, hold promise for application in soft robots due to their tunable physiochemical properties. Under certain environmental conditions, PNCs undergo stimuli-responsive structural rearrangement and transform the energy of the ambient environment into diverse uses, for example, repairing the injuries and reconfiguring the shapes of the materials. We develop PNCs with the ability of thermal-responsive restructuring by the stepwise assembly of functional components, including magnetite nanoparticles, silylated cellulose, and polydimethylsiloxane. We investigate the dynamic changes of the nano- and submicron structure of the magnetic PNCs upon the stimulation of heating based on a combined analytical approach: using dynamic mechanical analysis to interpret the viscoelastic properties of the PNC and in situ small-angle X-ray scattering to quantify the clustering of NPs. Based on these results, we formulate a structural model for the heating-induced evolution of the nano- to submicrometer assemblies in the magnetic PNC. Moreover, thermal-induced restructuring of magnetic PNCs leads to additional favorable functions, such as the abilities of healing, welding, reprocessing, and responses to photo and magneto stimuli. Our design provides a versatile means to develop responsive PNCs for applications in soft robots, sensors, and actuators.

Plasmons have facilitated diverse analytical applications due to the boosting signal detectability by hot spots. In practical applications, it is crucial to fabricate straightforward, large-scale, and reproducible plasmonic substrates. Dewetting treatment, via applying direct thermal annealing of metal films, has been used as a straightforward method in the fabrication of such plasmonic nanostructures. However, tailoring the evolution of the dewetting process of metal films poses considerable experimental complexities, mainly due to nanoscale structure formation. Here, we use grazing-incidence small- and wide-angle X-ray scattering for the in situ investigation of the high-power impulse magnetron sputter deposition of Ag on self-assembled Au nanoparticle arrays at low-temperature dewetting conditions. This approach allows us to examine both the direct formation of binary Au/Ag nanostructure and the consequential impact of the dewetting process on the spatial arrangement of the bimetallic nanoparticles. It is observed that the dewetting at 100 °C is sufficient to favor the establishment of a homogenized structural configuration of bimetallic nanostructures, which is beneficial for localized surface plasmon resonances (LSPRs). The fabricated metal nanostructures show potential application for the surface-enhanced Raman scattering (SERS) detection of rhodamine 6G molecules. As SERS platform, bimetallic nanostructures formed with dewetting conditions turn out to be superior to those without dewetting conditions. The method in this work is envisioned as a facile strategy for the fabrication of plasmonic nanostructures.

2D-3D tin-based perovskites are considered as promising candidates for achieving efficient lead-free perovskite solar cells (PSCs). However, the existence of multiple low-dimensional phases formed during the film preparation hinders the efficient transport of charge carriers. In addition, the non-homogeneous distribution of low-dimensional phases leads to lattice distortion and increases the defect density, which are undesirable for the stability of tin-based PSCs. Here, mixed spacer cations [diethylamine (DEA+) and phenethylamine (PEA+)] are introduced into tin perovskite films to modulate the distribution of the 2D phases. It is found that compared to the film with only PEA+, the combination of DEA+ and PEA+ favors the formation of homogeneous low-dimensional perovskite phases with three octahedral monolayers (n = 3), especially near the bottom interface between perovskite and hole transport layer. The homogenization of 2D phases help improve the film quality with reduced lattice distortion and released strain. With these merits, the tin PSC shows significantly improved stability with 94% of its initial efficiency retained after storing in a nitrogen atmosphere for over 4600 h, and over 80% efficiency maintained after continuous illumination for 400 h. Mixed spacer cations [diethylamine (DEA+) and phenethylamine (PEA+)] favor the formation of homogeneous low-dimensional tin perovskite phases with three octahedral monolayers (n = 3), especially near the bottom interface between perovskite and hole transport layer. The homogenization of 2D phases helps improve the film quality with reduced lattice distortion and released strain. image

Abstract Aluminum, due to its high abundance, very attractive theoretical capacity, low cost, low (de−) lithiation potential, light weight, and effective suppression of dendrite growth, is considered as a promising anode candidate for lithium‐ion batteries (LIBs). However, its practical application is hindered due to multiple detrimental challenges, including the formation of an amorphous surface oxide layer, pulverization, and insufficient lithium diffusion kinetics in the α‐phase. These outstanding intrinsic challenges need to be addressed to facilitate the commercial production of Al‐based batteries. The native passivation layer, Al2O3, plays a critical role in the nucleation and reversibility of lithiating aluminum and is thoroughly investigated in this study using high precision electrochemical micro calorimetry. The enthalpy of crystallization of β‐LiAl is found to be 40.5 kJ mol−1, which is in a strong agreement with the value obtained by calculation using Nernst equation (40.04 kJ mol−1). Surface treatment of the active material by the addition of 25 nm of alumina increases the nucleation energy barrier by 83 % over the native oxide layer. After the initial nucleation, the added alumina does not negatively impact the reversibility at 0.1 C rate, suggesting the removal of alumina is not necessary for improving the cyclability of aluminum anode based lithium‐ion batteries. Moreover, the coulombic efficiencies are also found to be slightly higher in the alumina treated samples compared to the untreated ones.

Polarised light is critical for a wide range of applications, but is usually generated by filtering unpolarised light, which leads to significant energy losses and requires additional optics. Herein, the direct emission of linearly-polarised light is achieved from light-emitting diodes (LEDs) made of CsPbI3 perovskite nanoplatelet superlattices. Through use of solvents with different vapour pressures, the self-assembly of perovskite nanoplatelets is achieved to enable fine control over the orientation (either face-up or edge-up) and therefore the transition dipole moment. As a result of the highly-uniform alignment of the nanoplatelets, as well as their strong quantum and dielectric confinement, large exciton fine-structure splitting is achieved at the film level, leading to pure-red LEDs exhibiting a high degree of linear polarisation of 74.4% without any photonic structures. This work unveils the possibilities of perovskite nanoplatelets as a highly promising source of linearly-polarised electroluminescence, opening up the development of next-generation 3D displays and optical communications from this highly versatile, solution-processable system.

The thermoelectric properties of fully sprayed thin films of poly(3-hexylthiophen-2,5-diyl) (P3HT) doped with chloroauric acid are investigated for different film thicknesses. The film thickness increases logarithmically with increasing amount of deposited material on the surfaces. Both the electrical conductivity and measured Seebeck coefficients of the doped thin films show an optimal polymer layer thickness between 275 and 310 nm and yield a maximum power factor of (1.77 ± 0.22) μW/m·K^2 . The optimum layer thickness results from the optimal amount of dopant molecules per monomer between 1.1 and 1.3 at these ratios of P3HT and HAuCl _4 for the thin film fabrication.

Titanium niobium oxide (TiNbxO2 + 2.5x) is emerging as a promising electrode material for rechargeable lithium-ion batteries (LIBs) due to its exceptional safety characteristics, high electrochemical properties (e.g., cycling stability and rate performance), and eco-friendliness. However, several intrinsic critical drawbacks, such as relatively low electrical conductivity, significantly hinder its practical applications. Developing reliable strategies is crucial to accelerating the practical use of TiNbxO2 + 2.5x-based materials in LIBs, especially high-power LIBs. Here, we provide a chronicle review of the research progress on TiNbxO2 + 2.5x-based anodes from the early 1950s to the present, which is classified into early stage (before 2008), emerging stage (2008–2012), explosive stage (2013–2017), commercialization (2018), steady development (2018–2022), and new breakthrough stage (since 2022). In each stage, the advancements in the fundamental science and application of the TiNbxO2 + 2.5x-based anodes are reviewed, and the corresponding developing trends of TiNbxO2 + 2.5x-based anodes are summarized. Moreover, several future research directions to propel the practical use of TiNbxO2 + 2.5x anodes are suggested based on reviewing the history. This review is expected to pave the way for developing the fabrication and application of high-performance TiNbxO2 + 2.5x-based anodes for LIBs.

Mixed halide perovskite nanocrystals in the form of cesium/formamidinium lead triiodide ((Cs:FA)PbI3) offer great potential for efficient and stable solar cells. To date, large-scale production with roll-to-roll compatible deposition methods remains difficult and requires detailed research on each involved processing step. Here, a proof-of-concept study about slot-die coating (printing) the active layer of (Cs:FA)PbI3-based nanocrystal solar cells is presented. Structural and morphological changes during ligand exchange of long-chain oleic acid and oleylamine by Pb(NO3)(2), and top-layer FAI passivation are investigated. Ligand exchange improves the processability of the nanocrystal layer and enhances charge transport. It also changes texture from face-on toward edge-on orientation as grazing-incidence X-ray scattering studies indicate. Ligand exchange and FAI passivation redshift photoluminescence and prolong charge carrier lifetime in the printed nanocrystal films. The proof-of-concept feasibility of printing metal halide perovskite nanocrystal films for solar cells is shown by building 20 devices with a median power conversion efficiency of 6.39%.

Battery safety is a multifaceted concern, with thermal runaway standing out as a primary issue. In this work, we introduce a novel temperature-responsive, self-protection electrolyte governed by the phase separation dynamics of poly (butyl methacrylate) (PBMA) in lithium salt/tetraglyme (G4) blends. This innovation effectively mitigates the risks associated with thermal runaway in lithium batteries. Our electrolyte exhibits a temperature-responsive-recovery characteristic, imparting intelligent capabilities to lithium batteries. At temperatures of >105 degrees C, the electrolyte transitions from a homogeneous phase to a segregated state, comprising a PBMA-rich phase with low conductivity and a high conductivity phase containing dissolved lithium salt in G4. The deposition of the PBMA-rich phase on the electrode surface obstructs the ion transport, thereby averting a thermal runaway. Subsequently, upon returning to room temperature of 25 degrees C, the electrolyte reverts to its homogeneous, highly conductive state, with battery capacity resuming at approximately 94 %. Thus, our electrolyte offers a robust, reversible, smart self-protection for batteries. Additionally, it demonstrates exceptional cycling performance at room temperature. Our findings open new avenues for thermo-reversible and self-protective electrolytes, advancing the safe and widespread adoption of lithium-ion batteries.

The swift progress in wearable technology has accentuated the need for flexible power systems. Such systems are anticipated to exhibit high efficiency, robust durability, consistent power output, and the potential for effortless integration. Integrating ultraflexible energy harvesters and energy storage devices to form an autonomous, efficient, and mechanically compliant power system remains a significant challenge. In this work, we report a 90 µm-thick energy harvesting and storage system (FEHSS) consisting of high-performance organic photovoltaics and zinc-ion batteries within an ultraflexible configuration. With a power conversion efficiency surpassing 16%, power output exceeding 10 mW cm–2, and an energy density beyond 5.82 mWh cm–2, the FEHSS can be tailored to meet the power demands of wearable sensors and gadgets. Without cumbersome and rigid components, FEHSS shows immense potential as a versatile power source to advance wearable electronics and contribute toward a sustainable future. The integration of ultraflexible energy harvesters and energy storage devices to form flexible power systems remains a significant challenge. Here, the authors report a system consisting of organic solar cells and zinc-ion batteries, exhibiting high power output for wearable sensors and gadgets.

Ternary hybrid thin films composed of a diblock copolymer templating two types of nanoparticles (NPs) expand the functionality of binary systems, which renders them interesting for magnetic sensing or magnetic data storage applications. Herein, one-pot slot-die printed hybrid polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) thin films are prepared with iron oxide (magnetite, Fe3O4, d = 20 nm) and nickel NPs (Ni, d = 46 nm) in one step by the advanced slot-die coating technique, which facilitates upscaling of fabrication. The evolution of the hybrid film morphology is probed with in situ grazing-incidence small-angle X-ray scattering and compared to that of a PS-b-PMMA thin film without NPs. Additionally, scanning electron microscopy and atomic force microscopy are used to analyze the surface morphology of hybrid films with an increasing NP content after deposition. It is found that different from the pure PS-b-PMMA thin film drying kinetics with five stages, the ternary hybrid film formation can be divided into four stages that are attributed first to the wet film, solvent evaporation, a subsequent rapid coalescence and microphase separation, and finally the dry film. The magnetic properties of the hybrid thin films are investigated with a superconducting quantum interference device magnetometer. All hybrid films are ferrimagnetic and with increasing nickel weight percent in the hybrid film, while the iron oxide weight percent is kept constant, the magnetic properties of the film are modulated accordingly.

Because of the detrimental effects of excessive exposure to solar ultraviolet radiation (UVR) on human skin health, wearable UVR detectors have attracted more and more attention. Inspired by the artwork "Tian-tsui hair pin with flora decoration" from the Palace Museum, a reversible and photochromic peony-shaped hairpin is designed to realize the visualized detection of solar UV radiation. It is prepared via electrospinning a mixed solution containing thermoplastic polyurethanes (TPUs) and Zn-MOF@WO3 onto microfiber nonwoven fabrics (MFNFs). Because of the enhanced UV responsive and photochromic capability from Zn-MOF@WO3 as well the excellent flexibility from TPUs and MFNFs, the obtained hairpin presents an excellent photoresponsive and wearable performance. When exposed to UV radiation from sunshine, the hairpin switches from white to light blue and finally to blue with radiation time. The colors light blue and blue can be used to indicate the UV radiation doses for the synthesis of vitamin D and the induction of erythema, respectively. With the assistance of oxygen in air, the hairpin recovers to its original state after being maintained in a dark atmosphere for 12 h. Even after six cycles of exposure to UV radiation and recovery in the dark, the photochromic performance almost remains unchanged. Only a minor reduction of 5% is observed. As a traditional wearable headdress in China, the peony-shaped hairpin prepared from the hybrid nanofibers not only presents oriental elegance but also is suitable for cyclical use in the daytime to monitor UV radiation for skin health management.

Cellulose is a natural polymer with great properties such as high optical transparency and mechanical strength, flexibility, and biodegradability. Hence, cellulose-based foils are suitable for the replacement of synthetic polymers as substrate materials in organic electronics. This article reports the fabrication of ultrathin, free-standing cellulose foils by spraying aqueous 2,2,6,6-tetramethylpiperidine-1-oxyl-nanocellulose (TEMPO) fibrils ink layer-by-layer on a hot substrate using a movable spray nozzle. The resulting foils are only 2 +/- 1 mu m in thickness with an average basis weight of 1.9 g m-2, which ranges in the same scale as the world's thinnest paper. The suitability of these ultra-thin nanocellulose foils as a sustainable substrate material for organic electronic applications is demonstrated by testing the foils resistance against organic solvents. Furthermore, silver nanowires (AgNWs) and the blend poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) are integrated into the foils, and the foils are molded into 3D paper structures in order to create conductive, paper-based building blocks for organic electronics. This article reports the fabrication of free-standing cellulose foils via layer-by-layer spray deposition. The foils are 2 mu m thin with an average basis weight of 1.9 g m-2, which ranges in the same scale as the world's thinnest paper. By integrating conductive nanoparticles and polymers, these foils become 3D, lightweight, functional components of individual shapes, suitable for organic electronics. image