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Intrinsic silicon (Si) is forbidden for infrared (IR) sensing at the communication wavelength like 1.31 or 1.55 µm due to the well‐known bandgap limitation. In this work, an unexpected physical picture of using argon (Ar) is identified, which is usually inert to the surrounding chemical environment and used as a protective agent in semiconductor processing, to overcome the IR‐sensing‐forbidden problem in Si. Here, it is shown by an analysis of a dynamic secondary ion mass spectrometer that such a Si, when exposed to laser pulse in Ar gas, can contain a very high dose of Ar up to 1020 cm−3 even after 1300 days. First‐principles calculations, molecular dynamics, and Hall effect measurements reveal that, due to both steric and dynamic repulsions by Ar orbitals to Si dangling bonds, the Ar‐filled‐vacancy produces a much wider defect band inside the gap, which is not only responsible for strong infrared absorption, but also causes a significant increase in n‐type conductivity, both in line with experiments. The study proves that originally inert elements in fact can act as active impurities in semiconductors for advanced applications, which updates the current knowledge of defect physics. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots (QDs) have been widely studied in display panels due to their near‐unity fluorescence quantum yield and the ability to tune colors across a wide gamut. However, the challenge persists in creating full‐color QD arrays with the necessary precision for high‐resolution display applications in the next generation. This paper introduces a femtosecond laser‐induced forward transfer (FsLIFT) technology that integrates deposition pattern and alignment in a single transfer step. This development enables the fabrication of high‐resolution full‐color QD films. The ability of FsLIFT to precisely locate red, green, and blue QDs in a designated position allows to obtain arbitrarily shaped full‐color patterns and pixel arrays with a resolution of 1.78 µm. In addition, the potential for optoelectronic devices is ensured by the preserved photophysical properties, high smoothness, and continuity of the transferred QD films. Consequently, the light‐emitting diodes (LEDs) are successfully fabricated based on the transferred QD films. This study expects that the introduced straightforward patterning technology, offering high freedom, precision, and repeatability, will contribute to advancing the development of full‐color high‐resolution displays based on QDs. [ABSTRACT FROM AUTHOR]

The rapid development of nanotechnology for the last 30 years has enabled a rapid expansion in the applications of functional nanoparticles (NPs) on optoelectronic devices. Especially, NPs are of high significance in organic light‐emitting diodes (OLEDs) as they provide feasible solutions to the enduring challenges related to higher device efficiency. The use of NPs with designed structure and functionality is demonstrated, indicative of their great application potentials in OLEDs. Herein, the recent advances in OLEDs with the utilization of functional NPs are summarized. Starting with a brief overview about the unique properties of NPs, comprehensive roles of NPs in OLEDs, which include improving carrier injection abilities, local surface plasmonic resonance, light scattering, and magnetic field effects, are discussed together with their latest research progresses. Furthermore, one‐component and multicomponent heterostructured NPs with multifunctional capabilities in OLEDs are overviewed. Following the summarization of the roles of NPs in OLEDs and their latest research progress, a brief conclusion and outlook regarding the future research directions of highly efficient OLEDs by incorporation of NPs are provided. [ABSTRACT FROM AUTHOR]

3D printing of inorganic materials with nanoscale resolution offers a different materials processing pathway to explore devices with emergent functionalities. However, existing technologies typically involve photocurable resins that reduce material purity and degrade properties. We develop a general strategy for laser direct printing of inorganic nanomaterials, as exemplified by more than 10 semiconductors, metal oxides, metals, and their mixtures. Colloidal nanocrystals are used as building blocks and photochemically bonded through their native ligands. Without resins, this bonding process produces arbitrary three-dimensional (3D) structures with a large inorganic mass fraction (~90%) and high mechanical strength. The printed materials preserve the intrinsic properties of constituent nanocrystals and create structure-dictated functionalities, such as the broadband chiroptical responses with an anisotropic factor of ~0.24 for semiconducting cadmium chalcogenide nanohelical arrays. [ABSTRACT FROM AUTHOR]

3D laser nanoprinting represents a revolutionary manufacturing approach as it allows maskless fabrication of 3D nanostructures at a resolution beyond the optical diffraction limit. Specifically, it endows the printed structures novel physical, chemical, or mechanical properties not observed at macroscopic scale. However, 3D laser nanoprinting typically relies on the photopolymerization process, indicating its limitation on the printable materials and functionalities. The capability to print diverse functional materials beyond polymer will enable a lot of new device applications in nanophotonics, microelectronics, and so on. One of the strategies is to use the 3D‐printed polymer structures as skeletons for functional material deposition, while another is to mix the functional components with the photocurable molecules and print the nanocomposites. More recently, several laser nanoprinting techniques beyond photopolymerization are also developed. In this review, the cutting‐edge technical innovation is summarized and a couple of examples are highlighted showing exciting applications of the printed structures in magnetic microrobots, photonics, and optoelectronics. Finally, the vision for existing challenges and future development in this field is shared. [ABSTRACT FROM AUTHOR]

Achieving higher brightness of a single-photon emitter (SPE) is central for advanced applications from quantum information processing to quantum sensing. However, most approaches of integrating quantum emitters and photonic resonators require accurately localizing the emitter into a photonic structure, which is a challenge. Here, we report using dielectric microspheres for laser focusing to create SPEs in hexagonal boron nitride and in situ enhance the emission via photonic coupling between the SPE and the dielectric microspheres. The photoluminescence intensity is increased by 2.4-fold, achieving a high brightness SPE with a saturation intensity of up to 19.6 Mcounts s−1. This approach provides a feasible way to generate a high-performance SPE while simultaneously enabling precise coupling of the quantum light source and optical resonators. [ABSTRACT FROM AUTHOR]

The development of dynamic 3D codes is widely studied, especially for smart information protection and advanced dynamic information encryption. However, it is challenging to fabricate information carriers with full color, dynamic properties under external stimuli, and high capacity, which restricts their applications. Here, microsized dynamic full color fluorescent 3D codes are successfully fabricated using the multilayer‐independent femtosecond laser‐induced forward transfer (FsLIFT) technology, which achieves simultaneous high‐resolution transferring and patterning. The combination and excitation of multilayered quantum dots film with different colors and patterns ensure dynamic information transformation of the 3D codes. Due to the high spatial resolution of the FsLIFT, the minimum line width of the patterns can reach 1.78 µm, which ensures a high capacity for encoding. In addition, the decoding process of the microsized dynamic fluorescent 3D codes only requires smartphones, microscope patches, and portable light sources. Finally, the facile fabrication and decoding process as well as the customizable patterning abilities demonstrate the practical application potential for the advanced dynamic coding. [ABSTRACT FROM AUTHOR]

Chemical Marangoni propulsion enables dynamic and untethered motion by generating surface tension gradient through chemical release, thereby having great potential for the development of insect‐scale self‐propelled robots. However, as the release and diffusion of chemical "fuels" are commonly uncontrollable, the Marangoni propulsion is unstable, thereby restricting robotic applications. Herein, the laser fabrication of superhydrophobic swimming robots to develop controllable Marangoni propulsion based on a photothermal composite of graphene and polydimethylsiloxane is reported. By combining the microfluidic channels with photothermal air chambers, a light‐triggered switch that can control the release of chemical "fuels" is proposed. Furthermore, a superhydrophobic surface is fabricated on the swimming robot by laser treatment, which reduced water resistance and promoted propulsion. On‐demand actuation and swimming route planning are realized by programming the alcohol/air segments in the releasing channels, on‐demand actuation and swimming route planning have been realized. As a proof‐of‐concept, a Marangoni swimming robot equipped with a miniature digital camera is used in an actual environment. Therefore, this study is expected to advance the practical applications of the chemical Marangoni effect in swimming robots. [ABSTRACT FROM AUTHOR]

Assembling perovskites into heterojunctions is an effective approach to achieve high‐performance photodetectors. Compared with vertical heterojunctions, in lateral heterojunction‐based photodetectors, the reflection loss is reduced because the active layer is in direct contact with light resulting in higher performance and better stability. However, lateral perovskite–perovskite heterojunctions are difficult to achieve using solution methods because the first formed film is easily dissolved by the solvent of the second precursor. In this study, a two‐step imprinting method is developed to fabricate lateral MAPbI3–MAPbBr3 microwire heterojunctions and realize a high‐performance photodetector with a responsivity and detectivity of 1207 A W−1 and 2.78 × 1013 Jones, respectively. At 0 V bias, the device exhibits a responsivity of up to 233 A W−1, which is more than double the previously reported best results. The high‐quality heterojunction endows the photodetectors with ultra‐high polarization sensitivity (Imax/Imin = 8.2) and long‐term stability, retaining 88.2% of its initial performance even after being exposed to air for 391 d. [ABSTRACT FROM AUTHOR]

2D perovskites have been considered as promising candidates for optoelectronic devices due to their good optical and electronic properties compared to 3D perovskites with significantly higher stability. Considering the commercial applications involving displays, image sensors, and fluorescent anti‐counterfeiting labels, the patterning technique of 2D perovskites is urgently required. However, existing patterning approaches still have challenges in high‐resolution fabrication. Here, a facile femtosecond laser direct writing method to fabricate arbitrarily patterned 2D perovskite films with well‐defined profiles and uniform fluorescence properties is developed. The flexible, fine, and non‐thermal diffused patterning abilities of femtosecond laser facilitate diverse 2D perovskite patterns exhibiting bright emission without any pinholes and cracks, as well as high resolution of approximate 2 µm line width. Based on this efficient patterning technique, this study demonstrates fluorescent anti‐counterfeiting labels (quick response code embedded with microlines) based on 2D perovskite films with high humidity stability, which can be identified from 43% to 96% relative humidity. This high‐resolution, reliable, efficient, and facile patterning technique for 2D perovskites with high humidity stability provides a promising technical route for 2D perovskite‐based optoelectronic applications. [ABSTRACT FROM AUTHOR]

Micro/nano optoelectronic devices based on curved substrates play a significant role in the development of wearable devices, electronic skin, conformal sensors, conformal antennas, and soft robots. However, the current fabrication processes are oriented toward planar micro/nano devices, and the fabrication of such devices on curved substrates is challenging. Herein, a temperature‐gradient‐assisted nanoimprint‐based in situ micro/nano‐crystal growth method is proposed to fabricate high‐quality curved perovskite microwire crystal (MWC) arrays on curved surfaces. Based on this curved perovskite MWC array without bending‐induced defects, high‐performance curved photodetectors (responsivity = 414 A W−1, detectivity = 1.2 × 1014 Jones, and external quantum efficiency over 140 000%) with extraordinary stability (85% of original performance maintained for more than 2 years) are fabricated to realize a curved imaging device. These results provide insights into the application of high‐performance perovskite photodetectors in nonconformal optical systems. [ABSTRACT FROM AUTHOR]

Stretchable organic light‐emitting devices (SOLEDs) based on orderly wrinkles have become a promising candidate for the new‐generation deformable displays because of their high‐optoelectronic performance and stretching stability. However, the complex thin film transfer process to form the wrinkles and the decreased display quality caused by the large‐period wrinkles with a few hundreds of microns are obstacles to their practical applications. Herein, a simple transfer‐free technique is designed to introduce the orderly wrinkles with a much smaller period of 70 µm into the SOLEDs, which is the smallest value reported to date for the orderly wrinkles integrated in the SOLEDs. The small‐period wrinkles are invisible by naked eyes and beneficial to the applications of the SOLEDs in high‐quality stretchable displays. The electroluminescence performance of the SOLED with 20% stretchability are comparable to those of the rigid OLEDs on glass substrates. After 2000 cycles of stretching, the luminance of the device remained at 90% of its initial value. Meantime, the transfer‐free technique is compatible with the flexible encapsulation process. The luminance of the encapsulated SOLEDs exhibit negligible decline after 600‐min continuous operation under ambient condition. This work provides an effective solution for achieving high‐performance SOLEDs by a simple process. [ABSTRACT FROM AUTHOR]

Optical crystals are ideal materials for complex functional and durable optical components, but their good stability and hardness bring about difficulties in high‐precision machining and require surface roughness below λ/10. Femtosecond laser ablation is a widely applicable processing method indifferent to material types, but its 3D fabrication capability is limited by the accumulation of ablated debris and rough ablated surface. This work demonstrates a universal and flexible technology for the fabrication of crystalline micro‐optics with required shape and surface roughness for the most demanding optical phase control. The cavitation‐assisted ablation by a direct laser writing mode is followed by a high‐temperature treatment to remove the rough non‐crystalline layer caused by ablation. The annealing at temperatures below the melting point of the crystal reduces the roughness down to ≈2 nm without changing the structure shape. This virtue of maintaining the designed shape without change, which is impossible during thermal morphing of 3D surfaces of glasses, allows for a previously unavailable flexibility of surface finish for the most demanding optical micro‐optical elements made in this study. This universal technology with nanoscale resolution and free‐form 3D manufacturing capability is applicable for various crystals and provides a new way to fabricate micro‐/integrated‐optics and nonlinear optical elements. [ABSTRACT FROM AUTHOR]

The assembly of colloidal particles into 2D or 3D superstructures is significant as the colloidal assembly exhibits collective behavior beyond the sum of single particles. Technically, colloidal particles can either self‐assemble when thermodynamic equilibrium is reached, or directed into specific assembly under external stimulus, such as electric, magnetic, acoustic, or light field. Specifically, light can be focused locally and manipulated in a precise manner, providing the possibility to tailor the assembly kinetics in different degrees of freedom. The understanding of light–matter interaction during the assembly process is challenging but critical for the design and fabrication of diverse colloidal superstructures. In this review, these particles are treated as artificial atoms at colloidal scale to mimic the organization of matter. From this aspect, the light‐directed assembly process is discussed on the basis of the roles of light, including light‐directed nucleation, diffusion, interparticle bonding, and phase control. Beyond what has been observed at atomic scale, colloidal atoms exhibit diversity in size, shape, and composition, and their bonding force is irrelevant to the electronic state, which enriches the geometric complexity of colloidal matter. Finally, the authors summarize the emerging applications of these colloidal superstructures in nanophotonics, nanocatalysis, and nanomedicine, and outline the major challenge and future development. [ABSTRACT FROM AUTHOR]

Soft robots controlled by different actuation schemes are flourishing owing to the continued development of smart materials. However, most of the existing actuators are powered by a single source with predetermined mechanical properties and motion characteristics. Speed, power, and efficiency of these actuators are thus far inferior to their conventional counter parts. How to preload or alter the internal energy distribution and trigger rapid kinetic energy release combined with re‐programmability is a challenge and corresponding solutions will extend the practical use of soft robotics. Herein, a hybrid magnetically and photothermally responsive actuator with high degrees of freedom by using a coupled‐field manipulation strategy is proposed. As a proof‐of‐concept, a crab robot (CraBot) that contains uniformly distributed superparamagnetic particles and localized light‐responsive joints is produced. The spatial magnetic field exerts force on the robot, leading to real‐time adjustment of energy distribution within the entire robot. Meanwhile, the focused light field enables selective deformation of specific joints, releasing the accumulated energy into kinetic energy of motion for quick actuation. The directional accumulation and addressable release of elastic energy enables the CraBot to walk efficiently with improved power and speed. Such a hybrid‐field manipulation strategy holds great promise for sophisticated actuation of soft robots. [ABSTRACT FROM AUTHOR]

Thin, lightweight micro‐diffractive optical elements (M‐DOEs) are of great significance to integrated optics. However, the narrow working bandwidth of M‐DOEs allows them to operate only at specific wavelengths. Existing solutions require multiple components assembly, which is difficult to implement in an integrated system. Here, a general designing and processing scheme of an optofluidic‐integrated broad‐bandwidth M‐DOE is reported, achieving an average diffraction efficiency of over 84% across the entire visible band (406–824 nm). As a proof‐of‐concept, a wideband operating micro‐diffractive lens and orbital angular momentum beam micro‐generator are demonstrated. This strategy provides a common protocol for various broad‐bandwidth M‐DOEs operating in integrated optical systems. [ABSTRACT FROM AUTHOR]

Comprehensive understanding of the interactions between excited states with spin‐valley polarizations is crucial for the applications of monolayer 2D transition metal dichalcogenides (TMDs) in spin‐valleytronics. Here, by broadband femtosecond transient absorption spectroscopy with circularly polarized pump/probe lights, a systematic investigation on the many‐body interactions of band‐edge valley excitons in monolayer MoS2 is performed, where intravalley coherent coupling processes are directly observed at room temperature. Namely, when the intravalley mixing states in the superposition region of A‐exciton and B‐exciton states are excited, there is an intravalley coherent coupling between A‐exciton and B‐exciton in K valley (or A′‐exciton and B′‐exciton in K′ valley) with an oscillation frequency of ≈7–8 THz, rather than the intervalley excitonic coupling in general. The findings elucidate intravalley mixing and coherent oscillations in valley excitons of monolayer TMDs at room temperature, which can give insight into the many‐body coupling mechanisms of excited valley excitons in 2D TMDs. [ABSTRACT FROM AUTHOR]

Nitrogen-vacancy (NV) color centers in diamonds with narrow optical linewidths are commonly used as solid-state single-photon sources that emit indistinguishable photons. However, NV color centers prepared using ion implantation typically have large optical linewidths of over 100 MHz. Herein, we used the femtosecond laser direct writing (FsLDW) technique to prepare single NV color centers in diamond with a narrow optical linewidth of 13.05 ± 0.2 MHz and a long decoherence time of 445 ± 27.6 μs. In addition, the density functional theory was adopted to establish calculation models and illustrate why single NV color centers prepared by FsLDW have narrower linewidths compared to those of the ion implantation method. Thus, this study provides an effective reference for the preparation of narrow-linewidth single-color centers in diamonds and other wide-gap crystals. [ABSTRACT FROM AUTHOR]

Color centers, optically active defects within solids, are vital for leading quantum information technologies such as quantum computing and quantum sensing. An essential prerequisite for realizing scalable quantum architectures is the ability to create quantum emitters deterministically. In the last decades, significant efforts have been devoted to selectively generating color centers. One of the most used methods is high‐energy ion implantation. However, this method usually causes extended lattice damage along the entire trajectory because of ions bombardment. Moreover, the position depth of color centers is also limited by the ions penetrate length in crystals. The direct laser‐writing (DLW) technique has recently emerged as a powerful tool to create color centers in solid‐state materials. It can define color centers at arbitrary depths inside the substrate and operate at the ambient environment, therefore, providing a feasible 3D fabrication method for integrated quantum photonics. Here, recent advancements of laser writing of color centers in solid‐state materials are reviewed, from bulk crystals, such as diamond and silicon carbide, to nanostructures, involving single‐walled carbon nanotubes, 2D layered materials, and quantum dots. [ABSTRACT FROM AUTHOR]

Photonic spin‐orbit interactions (PSOIs) in nanostructures have attracted much interest in nanophotonics, which provide a new paradigm to enhance light‐matter interactions and engineer the wavefronts of light on demand at the nanoscale. Many striking phenomena and functionalities, such as the photonic (quantum) spin‐Hall effect and the spin‐vortex conversion, have been demonstrated. Besides their underlying physics and manifestations, the experimental probing and imaging of PSOIs are also of great importance and highly demanded in not only the fundamental research but also the development of emerging PSOI technologies. Hence, in this review, the state‐of‐the‐art studies on the experimental observations and detections of PSOIs are systematically reviewed, including both the far‐field and near‐field methods. The respective advantages and difficulties of each method are stated and analyzed. The perspectives in probing PSOIs are also discussed. [ABSTRACT FROM AUTHOR]

Exciton related processes in two-dimensional (2D) transition metal dichalcogenides (TMDCs) play important roles in their optoelectronic applications. In this work, through broadband transient absorption spectroscopy, the electronic band structure evolution, exciton energy shifting dynamics and power-dependence spectral characteristics of WSe2 layers, including monolayer, bilayer, tri-layer and bulk WSe2 under 400 nm and 800 nm excitations are investigated. Particularly, under 400 nm excitation, due to the hot-exciton effect, the A-exciton energy shifting dynamics in WSe2 layers have been analysized in detail, where thicker WSe2 samples possess slower hot-exciton cooling lifetimes, and the exciton recombination approaches are affected by the band structure and interlayer interactions, in comparison with that under 800 nm excitation. The power-dependence spectral evolution in WSe2 layers suggests that the charged states like trions could be facilitated in tri-layer WSe2 (or thicker samples) at the same experimantal conditions. These findings in WSe2 layers could provide a deep insight into the hot-exciton related processes in 2D TMDCs from transient experiments ponit of view. [ABSTRACT FROM AUTHOR]

First-principles calculations reveal a Mexican-hat potential energy surface (PES) for two-dimensional (2D) In2Se3. This unique PES leads to a pseudo-centrosymmetric paraelectric β phase that resolves the current controversy between theory and experiment. We further show that while the α-to-β (ferroelectric-to-paraelectric) phase transition is fast and coherent, assisted by an in-plane shear phonon mode, a random distribution of the atoms in the trough of the PES acts as an entropy barrier against the reverse β-to-α transition. This will be the origin of the speed limitation of current In2Se3 ferroelectric devices. However, if one orders the β phase (due to the formation of in-plane ferroelectric domains), the reverse transition can take place within tens of picoseconds in the presence of a perpendicular electric field. Finally, the Mexican-hat PES is a general feature for the entire family of 2D III2-VI3 materials. Our finding offers a critical physical picture in controlling the ultrafast reversible phase transition in 2D In2Se3 and other III2-VI3 materials, which will benefit their practical industrial development for advanced ferroelectric devices. [ABSTRACT FROM AUTHOR]

Generalization of the concept of band topology from lower-dimensional to higher-dimensional (n > 3) physical systems is expected to introduce new bulk and boundary topological effects. However, theoretically predicted topological singularities in five-dimensional systems—Weyl surfaces and Yang monopoles—have either not been demonstrated in realistic physical systems or are limited to purely synthetic dimensions. We constructed a system possessing Yang monopoles and Weyl surfaces based on metamaterials with engineered electromagnetic properties, leading to the observation of several intriguing bulk and surface phenomena, such as linking of Weyl surfaces and surface Weyl arcs, via selected three-dimensional subspaces. The demonstrated photonic Weyl surfaces and Weyl arcs leverage the concept of higher-dimension topology to control the propagation of electromagnetic waves in artificially engineered photonic media. [ABSTRACT FROM AUTHOR]

Phase change memory (PCM) is an emerging non‐volatile data storage technology concerned by the semiconductor industry. To improve the performances, previous efforts have mainly focused on partially replacing or doping elements in the flagship Ge‐Sb‐Te (GST) alloy based on experimental "trial‐and‐error" methods. Here, the current largest scale PCM materials searching is reported, starting with 124 515 candidate materials, using a rational high‐throughput screening strategy consisting of criteria related to PCM characteristics. In the results, there are 158 candidates screened for PCM materials, of which ≈68% are not employed. By further analyses, including cohesive energy, bond angle analyses, and Born effective charge, there are 52 materials with properties similar to the GST system, including Ge2Bi2Te5, GeAs4Te7, GeAs2Te4, so on and other candidates that have not been reported, such as TlBiTe2, TlSbTe2, CdPb3Se4, etc. Compared with GST, materials with close cohesive energy include AgBiTe2, TlSbTe2, As2Te3, TlBiTe2, etc., indicating possible low power consumption. Through further melt‐quenching molecular dynamic calculation and structural/electronic analyses, Ge2Bi2Te5, CdPb3Se4, MnBi2Te4, and TlBiTe2 are found suitable for optical/electrical PCM applications, which further verifies the effectiveness of this strategy. The present study will accelerate the exploration and development of advanced PCM materials for current and future big‐data applications. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO), which has many oxygen functional groups, is a promising candidate for use in moisture‐responsive sensors and actuators due to the strong water–GO interaction and the ultrafast transport of water molecules within the stacked GO sheets. In the last 5 years, moisture‐responsive actuators based on GO have shown distinct advantages over other stimuli‐responsive materials and devices. Particularly, inspired by nature organisms, various moisture‐enabled soft robots have been successfully developed via rational assembly of the GO‐based actuators. Herein, the milestones in the development of moisture‐responsive soft robots based on GO are summarized. In addition, the working mechanisms, design principles, current achievement, and prospects are also comprehensively reviewed. In particular, the GO‐based soft robots are at the forefront of the advancement of automatable smart devices. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO), which has many oxygen functional groups, is a promising candidate for use in moisture‐responsive sensors and actuators due to the strong water–GO interaction and the ultrafast transport of water molecules within the stacked GO sheets. In the last 5 years, moisture‐responsive actuators based on GO have shown distinct advantages over other stimuli‐responsive materials and devices. Particularly, inspired by nature organisms, various moisture‐enabled soft robots have been successfully developed via rational assembly of the GO‐based actuators. Herein, the milestones in the development of moisture‐responsive soft robots based on GO are summarized. In addition, the working mechanisms, design principles, current achievement, and prospects are also comprehensively reviewed. In particular, the GO‐based soft robots are at the forefront of the advancement of automatable smart devices. [ABSTRACT FROM AUTHOR]

Organic single crystals are highly promising for applications in optoelectronic devices because of their higher mobility and thermal stability than amorphous thin films. Although white organic single crystals have been fabricated by the double-doped method and applied to realize white organic light‐emitting devices (WOLEDs), the unbalanced carrier transport properties of the unipolar crystals severely limit the device performance. Here, ambipolar white organic single crystals are obtained by using mixed p- and n-type molecules as an ambipolar host for the red and green dopants. The white crystal with balanced carrier transport and balanced blue, green, and red emission intensity was applied to the single-crystal WOLEDs. The highest brightness of 1956 cd m−2 and the current efficiency of 1.31 cd A−1 are achieved, which are the best performance of the single-crystal WOLEDs reported to date. A high color rendering index is obtained, which varies between 82 and 87 with increasing driving current. It is expectable that this strategy would support the practical applications of organic single crystal-based OLEDs. [ABSTRACT FROM AUTHOR]

Band renormalization effects play a significant role for two-dimensional (2D) materials in designing a device structure and customizing their optoelectronic performance. However, the intrinsic physical mechanism about the influence of these effects cannot be revealed by general steady-state studies. Here, band renormalization effects in organic superacid treated monolayer MoS2, untreated monolayer MoS2 and few-layer MoS2 are quantitatively analyzed by using broadband femtosecond transient absorption spectroscopy. In comparison with the untreated monolayer, organic superacid treated monolayer MoS2 maintains a direct bandgap structure with two thirds of carriers populated at K valley, even when the initial exciton density is as high as 2.05 × 1014 cm−2 (under 400 nm excitations). While for untreated monolayer and few-layer MoS2, many-particle induced band renormalizations lead to a stronger imbalance for the carrier population between K and Q valleys in k space, and the former experiences a direct-to-indirect bandgap transition when the initial exciton density exceeds 5.0 × 1013 cm−2 (under 400 nm excitations). Those many-particle induced band renormalization processes further suggest a band-structure-controlling method in practical 2D devices. [ABSTRACT FROM AUTHOR]

Direct light‐to‐work conversion enables remote actuation through a non‐contact manner, among which the photothermal Marangoni effect is significant for developing light‐driven robots because of the diversity of applicable photothermal materials and light sources, as well as the high energy conversion efficiency. However, the lack of nanotechnologies that enable flexible integration of advanced photothermal materials with actuators of complex configurations significantly restricts their practical applications. In this paper, laser‐induced graphene (LIG) tape is reported as stick‐on photothermal labels for developing light‐driven actuators based on the Marangoni effect. With the help of direct laser writing technology, graphene patterns with superior photothermal properties are prepared on the PI tape. The patterned LIG tape can be stuck on any desired objects and generates an asymmetric photothermal field under light irradiation, forming a photothermal Marangoni actuator. Additionally, the PI tape with LIG patterns can be folded into 3D origami actuators that permit photothermal Marangoni actuation including both translation and rotation. The graphene‐based photothermal Marangoni actuators feature biocompatibility, which is confirmed by MDA‐MB‐231 cells proliferation experiments. Owing to the excellent photothermal property of LIG patterns, the as‐produced photothermal actuators can be manipulated by a variety of light sources, holding great promise for developing light‐driven soft robots. [ABSTRACT FROM AUTHOR]

Carrier mobility is one of the key issues for applications of organic semiconductors in electronic and optoelectronic devices. Organic single crystals possess much higher carrier mobility compared to amorphous films. However, unipolar properties with unbalanced hole and electron transporting ability have been a bottleneck for the high performance of organic single crystal‐based devices. Here, well‐balanced ambipolar organic single crystals are developed by mixing of n‐ and p‐type molecules with maintained single‐crystalline structures. Carrier mobility of the ambipolar single crystals is manipulated by tuning the mixing ratio, and nearly equal hole and electron mobility can be achieved. Highly efficient single crystal‐based organic light‐emitting devices (OLEDs) are demonstrated by employing the ambipolar crystals as the mixed host for a red emitter pentacene to realize efficient exciton confinement and energy transfer within the emissive layer. As a result, maximum luminance of 5467 cd m−2 and current efficiency of 2.82 cd A−1 are achieved, which represents, to the best of the authors' knowledge, the record performance for the organic single crystal‐based OLEDs to date. The strategy to manipulate the charge‐transport properties of the organic single crystals in this work represents a significant step toward practical applications of the organic single crystals in optoelectronics. [ABSTRACT FROM AUTHOR]

In recent years, orbital angular momentum (OAM) beams and their generation methods have drawn increasing interest. Generating multiple OAMs in a three-dimensional space simply and efficiently is meaningful and challenging. Herein, we proposed an integrated multi-OAM generator based on the independent controlling phase division. Realized through the two-photon additive manufacturing, the device possesses a continuous surface with a diameter of 100 μm. Using the generator, arbitrary OAM modes were demonstrated, including the axial position, the number of topological charges, and the direction of rotation. The unique optical characteristics were mutually verified experimentally and through simulation. Vortex beams carrying multiple OAMs will provide more degrees of freedom to manipulate light for exciting applications such as optical communications, micromanipulation, and quantum optics. [ABSTRACT FROM AUTHOR]

Micro‐ring resonators are widely used in many fields due to their compact structure, high integration, and rich functions. In recent years, perovskite materials have been widely concerned because of their superior properties and various shapes of perovskite‐based optical resonators have been achieved. Despite the excellent photoelectric properties of perovskite materials, it is difficult to realize micro‐ring resonators based on perovskite materials due to its tendency to crystallize into cubic structures. Here, this problem is solved by a microstructure edge‐guided crystallization method to fabricate shape‐designable and size‐tunable methylammonium lead bromide (MAPbBr3) micro‐ring resonator arrays with high performance. [ABSTRACT FROM AUTHOR]

Organic light‐emitting devices on fabrics (Fa‐OLEDs) are outstanding candidates for high‐quality wearable displays. High flexibility and conformality to clothes deformations are required for Fa‐OLEDs to keep wearing comfort during body movement. However, it is a great challenge to realize an ultrathin planarization layer with ultrasmooth surface simultaneously on the rough surface of fabrics for Fa‐OLEDs fabrication. Here, a template‐stripping process is employed to fabricate both ultrathin and ultrasmooth planarization layers for highly flexible and efficient Fa‐OLEDs. The thickness of the planarization layer is as small as 3 µm while its surface roughness is only 0.6 nm. The planarization process is insensitive to the textures and morphology of fabrics. As a result, the Fa‐OLEDs show excellent electroluminescent performance and flexibility. The maximum current efficiency of 78 cd A−1 is comparable with that of the conventional planar devices. The variation of current efficiency is as small as 8% after 1000 times of bending with 1 mm bending radius, which is the best bending stability of the flexible Fa‐OLEDs reported to date. The Fa‐OLEDs are successfully used as conformal wearable displays by sewing on clothes and keep working well with a series of arm movements. [ABSTRACT FROM AUTHOR]

Graphene-based actuators featuring fast and reversible deformation under various external stimuli are promising for soft robotics. However, these bimorph actuators are incapable of complex and programmable 3D deformation, which limits their practical application. Here, inspired from the collective coupling and coordination of living cells, we fabricated a moisture-responsive graphene actuator swarm that has programmable shape-changing capability by programming the SU-8 patterns underneath. To get better control over the deformation, we fabricated SU-8 micropattern arrays with specific geometries and orientations on a continuous graphene oxide film, forming a swarm of bimorph actuators. In this way, predictable and complex deformations, including bending, twisting, coiling, asymmetric bending, 3D folding, and combinations of these, have been achieved due to the collective coupling and coordination of the actuator swarm. This work proposes a new way to program the deformation of bilayer actuators, expanding the capabilities of existing bimorph actuators for applications in various smart devices. [ABSTRACT FROM AUTHOR]

Defects play a central role in controlling the electronic properties of two‐dimensional (2D) materials and realizing the industrialization of 2D electronics. However, the evaluation of charged defects in 2D materials within first‐principles calculation is very challenging and has triggered a recent development of the WLZ (Wang, Li, Zhang) extrapolation method. This method lays the foundation of the theoretical evaluation of energies of charged defects in 2D materials within the first‐principles framework. Herein, the vital role of defects for advancing 2D electronics is discussed, followed by an introduction of the fundamentals of the WLZ extrapolation method. The ionization energies (IEs) obtained by this method for defects in various 2D semiconductors are then reviewed and summarized. Finally, the unique defect physics in 2D dimensions including the dielectric environment effects, defect ionization process, and carrier transport mechanism captured with the WLZ extrapolation method are presented. As an efficient and reasonable evaluation of charged defects in 2D materials for nanoelectronics and other emerging applications, this work can be of benefit to the community. [ABSTRACT FROM AUTHOR]

Inefficient and wide‐angle emission as well as low emission rate of optical nanoemitters (such as quantum dots) have been strongly limiting their practical applications in next‐generation nanophotonic devices, such as nanoscale light‐emitting diodes (LEDs) and on‐chip single photon sources. Optical nanoantennas provide a promising way to deal with these challenges. Yet, there has been no solution that can overcome these drawbacks simultaneously on a single device. Here, a hybrid plasmonic nanoantenna consisting of a silver nanocube positioned at the center of a gold concentric‐ring structure is proposed, which can simultaneously enhance the emission directionality and decay rate of quantum dots embedded in the nanogap beneath the nanocube while maintaining high quantum efficiency. Coupling quantum dots to this nanoantenna can result in 60% of the emitted photons collected by the first lens with a numerical aperture (NA) of 0.5 and 21% for a NA of 0.12. The total emission intensity and decay rate are enhanced by 121‐fold and 424‐fold, respectively, compared with quantum dots on a glass substrate. A high quantum efficiency above 50% is obtained in simulation. This novel platform can be applied to enhance various types of optical nanoemitters and to develop high‐speed directional nano‐LEDs and single photon sources. [ABSTRACT FROM AUTHOR]

Stretchable organic optoelectronic devices have been developed rapidly in the last few years due to their great potential in wearable electronics. Although high performance is obtained, high‐throughput manufacturing of these devices is still a challenge for their commercial application. Here, a roller‐assisted adhesion imprinting (RAI) technique is developed to overcome this challenge by rapid production of ordered and large‐area wrinkled structures on organic optoelectronic devices to enable their stretchability. Different from the conventional imprinting technology requiring heating or ultraviolet treatment, adhesion force is employed innovatively in the RAI process to form microstructures within the imprinted materials. As a demonstration, a stretchable wrinkled structure with its length of more than 10 cm is rapidly fabricated and larger area is available by continuous imprinting. Stretchable organic light‐emitting devices (SOLEDs) are easily manufactured by the RAI process. The SOLEDs can be elongated to 100% strain and keep working with 5% current efficiency variation after 35 000 cycles of stretching with 20% tensile strain. This is the best mechanical stability of SOLEDs reported to date. The development of the high‐throughput, large‐area, and cost‐effective RAI technique provides potential roll‐to‐roll continuous production of stretchable electronics. [ABSTRACT FROM AUTHOR]

Keywords: 3D printing; functionality; nanomaterials; nanophotonics; two-photon polymerization EN 3D printing functionality nanomaterials nanophotonics two-photon polymerization 1 1 1 09/28/23 20230926 NES 230926 B 3D Printing b 3D laser nanoprinting provides a powerful tool to construct diverse materials into complex 3D geometries with the resolution down to the nanometer scale and endows the structures with fascinating functionalities. 3D printing, functionality, nanomaterials, nanophotonics, two-photon polymerization In article number 2211280, Linhan Lin, Zhengcao Li, Hong-Bo Sun, and co-workers summarize the cutting-edge technical innovations from polymer-based printing to polymer-free printing and highlight examples of exciting applications in magnetic microrobots, photonics, and optoelectronics. [Extracted from the article]

• A complementary strategy can work as a universal design principle for dual-responsive actuators. • Combining moisture-active/alkane-inert GO with alkane-active/moisture-inert PDMS enables dual-responsive actuation. • GO and PDMS bimorph features fast and reversible response to both moisture and alkane. Smart actuators that enable deforming in a predictable manner under external stimuli have revealed great potential for both traditional and emerging industries. Generally, an asymmetric bilayer structure with one layer active and the other inert to a certain stimulus is essential to realize bending behavior. However, towards the development of dual- or multi-responsive actuators, it still lacks universal and effective strategies for rational design and fabrication of such devices through the simplest way. In this paper, we report a complementary strategy to produce dual-responsive bilayer actuators by combining the moisture-active/alkane-inert graphene oxide (GO) layer with the alkane-active/moisture-inert polydimethylsiloxane (PDMS) layer. The GO@PDMS bimorph actuator can switch its active and inert layers in response to moisture and alkane, respectively, realizing dual-responsive deformation under different actuations. Typical dual-responsive actuators, including a selective air valve and a grip and hook smart claw, are successfully fabricated, demonstrating the capability of effective gases and objects transmission. The complementary bimorph actuator may hold great promise for developing intelligent devices and portable delivery systems. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • An ultrathin Au/graphene composite electrode with high transmittance and conductivity has been demonstrated. • The ultrathin Au/graphene composite electrode is applied to supercapacitor. • Flexible and transparent supercapacitor with the composite electrode exhibits high capacitance and mechanical stability. Abstract Large-area monolayer graphene by chemical vapor deposition as electrode in electronic devices always suffers from shortages of low conductivity and high contact resistance. In this work, we demonstrate a composite electrode by depositing a continuous and homogeneous ultrathin 7-nm Au film on monolayer graphene with low average sheet resistance of 24.6 Ω/□ and high transmittance of 74.6% at 520 nm. The excellent properties of the composite electrode are attributed to the suppressed Au Volmer-Weber growth mode of the ultrathin Au film by the organized hexagonal carbon lattices of graphene. Rigid supercapacitor based on the composite electrode exhibits a capacitance of 81.5 μF/cm2 at the scan rate of 0.1 V/s, which is 17 times higher than the device based on monolayer graphene. Flexible supercapacitor based on the composite electrode can be bending at curvature radius of 2 mm and with slight performance decrease over 1800 bending cycles. [ABSTRACT FROM AUTHOR]

A crystalline silicon (Si) surface was modified using nanosecond laser pulses in an argon atmosphere. The laser-modified Si (M-Si) samples have a higher performance and thermostable absorption in the broadband range (400–2400 nm) than conventional Si. The concentration of carrier electrons in the M-Si layer is at least five orders of magnitude greater than the carrier concentration of the Si substrate. Using the N+–N− junction formed between the M-Si layer and the Si substrate, visible and near-infrared (VIS-NIR) M-Si photodetectors are made. The N+–N− photodiode has good rectification characteristics and a high photoresponse to the subbandgap NIR light at 1310 nm. At the same time, the M-Si photodetector at a low reverse bias shows a large gain to the VIS-NIR light above the bandgap. By comparing the response time of the M-Si photodetector to the light of 900 and 1310 nm, the response speed of the device to the photon above-bandgap energy is faster. [ABSTRACT FROM AUTHOR]

Abstract: Actuators that can convert environmental stimuli into mechanical work are widely used in intelligent systems, robots, and micromechanics. To produce robust and sensitive actuators of different scales, efforts are devoted to developing effective actuating schemes and functional materials for actuator design. Carbon‐based nanomaterials have emerged as preferred candidates for different actuating systems because of their low cost, ease of processing, mechanical strength, and excellent physical/chemical properties. Especially, due to their excellent photothermal activity, which includes both optical absorption and thermal conductivities, carbon‐based materials have shown great potential for use in photothermal actuators. Herein, the recent advances in photothermal actuators based on various carbon allotropes, including graphite, carbon nanotubes, amorphous carbon, graphene and its derivatives, are reviewed. Different photothermal actuating schemes, including photothermal effect–induced expansion, desorption, phase change, surface tension gradient creation, and actuation under magnetic levitation, are summarized, and the light‐to‐heat and heat‐to‐work conversion mechanisms are discussed. Carbon‐based photothermal actuators that feature high light‐to‐work conversion efficiency, mechanical robustness, and noncontact manipulation hold great promise for future autonomous systems. [ABSTRACT FROM AUTHOR]

The combination of surface-enhanced Raman spectroscopy (SERS) technology with microfluidics makes it possible to diagnose genetic disease through label-free on-chip DNA detection. However, open problems including the integration of SERS substrate with microfluidic devices, controllable trapping and releasing of target molecules are still challenging. Here we demonstrate a facile laser scribing method to fabricate silver nanoparticles (AgNPs) and graphene oxide (GO) based biochips as a reusable SERS sensor for DNA detection. Programmable laser scribing of the AgNPs@GO composite film enables direct patterning of sensitive SERS channels that consist of graphene supported AgNPs by exfoliating the composites into hierarchical porous structures. Integrating the SERS-active patterns with a microfluidic chip forms a biochip for allowing SERS detection of DNA. The noncovalent interactions between DNA and graphene mediated controllable trapping and releasing of DNA sequences, enabling efficient on-chip SERS detection and the regeneration of the biochip. The simple, green and cost-effective fabrication of the SERS-active biochips reveals great potential for biomolecular sensing and genetic engineering applications. [ABSTRACT FROM AUTHOR]

Objective. We aimed to investigate the effectiveness of acupoint polyglactin 910 (PGLA) embedding in patients with cervical spondylotic radiculopathy (CSR). Methods. A total of 102 CSR patients with neck and shoulder pain were recruited and assigned randomly into three groups: the sham acupoint embedding (SAE) group, the middle-layer acupoint PGLA embedding (MAPE) group, and the deep-layer acupoint PGLA embedding (DAPE) group. The primary outcomes were Visual Analog Scale (VAS) scores showing the analgesic effects of treatment. Secondary outcomes included clinical symptoms (evaluated by the Yasuhisa Tanaka 20 (YT-20) score and the neck disability index (NDI)) and patient health status (evaluated by the 36-item short-form survey (SF-36)) as reported in the trial. Results. Compared with the SAE group, VAS scores were significantly reduced at 1, 2, 3, 4, and 10 weeks after the first treatment in both the DAPE and MAPE groups (P < 0.001). Moreover, there were statistically significant increases in the weekly YT-20 scores and significant reductions of the weekly NDI scores compared with baseline values in both the DAPE and MAPE groups (P < 0.001). Compared with baseline values, both the physical component summary (PCS) and the mental component summary scores of the SF-36 at 2, 3, 4, and 10 weeks were significantly higher in the DAPE and MAPE groups (P < 0.001). There were significant lower VAS scores (P < 0.01), higher PCS scores (P < 0.05) at 3 weeks, and lower NDI scores (P < 0.05) at 4 weeks in the DAPE group compared with the MAPE group. Conclusions. Both DAPE and MAPE showed significant and long-lasting effects on alleviating pain and improving clinical symptoms as well as quality of life in CSR patients with neck and shoulder pain. A more intense effect was seen in the DAPE group compared with the MAPE group. [ABSTRACT FROM AUTHOR]

• Inspired by chameleon, dynamic fluorescent patterns were successfully achieved. • By facilely controlling the excitations, the dynamically display was demonstrated. • Flexible information encryption and information decryption was achieved. • Micro-sized patterns were fabricated by femtosecond laser-induced forward transfer. Chameleon can display variable body color/patterns under environmental stimulation via bioelectricity-controlled three layers of pigment cells and photonic crystals in the chameleon's skin. Inspired by color variation of chameleon, numerous "smart skins" have been achieved successfully, which possess great potential for optical information record and security. However, it remains challenging to produce full color dynamic fluorescent patterns with higher precision and flexibility to improve information capacity and anti-counterfeiting property. In this work, the micro-sized full color dynamic fluorescent patterns were successfully achieved by multiple transferring different colored quantum dots (QDs) from the carrier substrates to the receiving substrate via femtosecond laser-induced forward transfer (FsLIFT) technology using the chameleon skin as a prototype. The ability to dynamically display by facilely controlling the excitations is demonstrated, ensuring the information transformation function as chameleon skin. The resulting dynamic fluorescent patterns provide dual biomimetic of chameleon skin morphology and function. To illustrate the promising practical applications, flexible information encryption and information decryption relying on portable devices based on the fabricated dynamic fluorescent patterns have been achieved. It is anticipated that this bioinspired strategy is universal and promising for fabricating on-demand fluorescent dynamic patterns. [ABSTRACT FROM AUTHOR]

Metasurfaces, planer artificial materials composed of subwavelength unit cells, have shown superior abilities to manipulate the wavefronts of electromagnetic waves. In the last few years, metasurfaces have been a burgeoning field of research, with a large variety of functional devices, including planar lenses, beam deflectors, polarization converters, and metaholograms, being demonstrated. Up to date, the majority of metasurfaces cannot be tuned postfabrication. Yet, the dynamic control of optical properties of metasurfaces is highly desirable for a plethora of applications including free space optical communications, holographic displays, and depth sensing. Recently, much effort has been made to exploit active materials, whose optical properties can be controlled under external stimuli, for the dynamic control of metasurfaces. The tunability enabled by active materials can be attributed to various mechanisms, including but not limited to thermo‐optic effects, free‐carrier effects, and phase transitions. This short review summarizes the recent progress on tunable metasurfaces based on various approaches and analyzes their respective advantages and challenges to be confronted with. A number of potential future directions are also discussed at the end. Various mechanisms to achieve dynamic control of metasurfaces enabled by active materials are discussed. Recent works on tunable metasurfaces based on thermo‐optic effects, free carrier effects, and phase transitions are summarized. Their respective advantages and challenges are analyzed and an outlook on the potential development of tunable metasurfaces is presented. [ABSTRACT FROM AUTHOR]

Strong coupling is an intriguing phenomenon where a physical system is generated through the interaction of two or more components. Transient absorption spectroscopy, a thoroughly validated technique for studying strong coupling, is based on a pump‐probe solution, and can follow the energy relaxation of strongly coupled systems over time. In article number 1801761, Hai Wang, Remo Proietti Zaccaria, and co‐workers present some of the most important results achieved in this field to date. [ABSTRACT FROM AUTHOR]

Since the birth of quantum mechanics the construction and control of novel hybrid quantum states are among the dream targets of scientists. In this regard, due to recent technological advances, hybrid states based on strong coupling occurring between light and matter have become a laboratory reality. For example, it is demonstrated that strong coupling involving microcavities or surface plasmon polaritons shows great potential for novel nanoplasmonic devices such as lasers, all‐optical switching, field‐effect transistors, and for the evergreen field of quantum computation. Further developments in this field require, however, a better understanding of the underlying mechanisms governing strong coupling, especially from a time‐dependent point of view, time‐resolved spectroscopy being one of the leading experimental approaches to address this aspect. In this perspective, after a brief introduction of the strong coupling concept, the recent research progress on the dynamics of strongly coupled systems involving J‐aggregates, broadly absorptive dyes, semiconductor quantum dots, and perovskite films with either microcavities or surface plasmons polaritons is summarized and discussed. Finally, challenges and perspectives for developing strong coupling concept are further illustrated, with special attention to phonon–photon interaction, as one of the most intriguing topics in condensed matter physics. Strong coupling is foreseen to be a key element for the next generation of electro/photonic devices. Even though, many open questions still exist regarding strongly coupled systems due to their fast temporal response. Here, an overview on transient absorption spectroscopy as one of the main tools with sufficient time resolution to investigate the physics of these systems is given. [ABSTRACT FROM AUTHOR]