Self‐Assembly of π‐Conjugated Amphiphiles: Free Standing,Ordered Sheets with Enhanced Mobility

Oligo(p‐phenylenevinylenes) (OPVs) with amphiphilic character are synthesized and their self‐assembly characteristics studied. Careful studies point at two morphologically different states of assemblies, with one being two dimensional sheets and the other as rolled tubes. This is also the first time that self‐assembled sheets are achieved for OPVs. Morphological and photo‐physical studies reveal a unique aggregate to aggregate transition between rolled tubes and two dimensional sheets, which is outlined as a more thermodynamic aggregate. The thermodynamic aggregate (2D sheet) is better ordered and consists of chromophores that are better excitonically coupled. The mobilities of these aggregates are also studied for a field effect transistor device and as expected sheets supersede rolled tubes by a couple of orders. More interestingly, the mobility values obtained for the well ordered chromophores in sheets is three orders higher than any other self‐assembled OPV previously reported. It is hypothesized that the better π interactions enforced by the amphiphilic design and the resultant supramolecular organization is a prime factor for such a remarkable rise in mobilities.     

Self‐Powered Trace Memorization by Conjunction of Contact‐Electrification and Ferroelectricity

Triboelectric nanogenerator (TENG) is a newly invented technology that can effectively harvest ambient mechanical energy from various motions with promising applications in portable electronics, self‐powered sensor networks, etc. Here, by coupling TENG and a thin film of ferroelectric polymer, a new application is designed for TENG as a self‐powered memory system for recording a mechanical displacement/trace. The output voltage produced by the TENG during motion can polarize the dipole moments in the ferroelectric thin film. Later, by applying a displacement current measurement to detect the polarization density in the ferroelectric film, the motion information of the TENG can be directly read. The sliding TENG and the single‐electrode TENG matrix are both utilized for realizing the memorization of the motion trace in one‐dimensional and two‐dimensional space, respectively. Currently, the ferroelectric thin film with a size of 3.1 mm² can record a minimum area changing of 30 mm² and such resolution can still be possibly improved. These results prove that the ferroelectric polymer is an effective memory material to work together with TENG and thereby the fabricated memory system can potentially be used as a self‐powered displacement monitor.     

Ultrasonication‐Induced Self‐Assembled Fixed Nanogap Arrays of Monomeric Plasmonic Nanoparticles inside Nanopores

Monomeric gold (Au) and silver (Ag) nanoparticle (NP) arrays are self‐assembled uniformly into anodized aluminium oxide (AAO) nanopores with a high homogeneity of greater than 95%, using ultrasonication. The monomeric metal NP array exhibits asymmetric plasmonic absorption due to Fano‐like resonance as interpreted by finite‐difference time‐domain (FDTD) simulation for the numbers up to 127 AuNPs. To examine gap distance‐dependent collective‐plasmonic resonance, the different dimensions of S, M, and L arrays of the AuNP diameters/the gap distances of ≈36 nm/≈66 nm, ≈45 nm/≈56 nm, and ≈77 nm/≈12 nm, respectively, are prepared. Metal NP arrays with an invariable nanogap of ≈50 nm can provide consistent surface‐enhanced Raman scattering (SERS) intensities for Rhodamine 6G (Rh6G) with a relative standard deviation (RSD) of 3.8–5.4%. Monomeric arrays can provide an effective platform for 2D hot‐electron excitation, as evidenced by the SERS peak‐changes of 4‐nitrobenzenethiol (4‐NBT) adsorbed on AgNP arrays with a power density of ≈0.25 mW µm^‐2 at 514 and 633 nm. For practical purposes, the bacteria captured by 4‐mercaptophenylboronic acid are found to be easily destroyed under visible laser excitation at 514 nm with a power density of ≈14 mW µm^‐2 for 60 min using Ag due to efficient plasmonic‐electron transfer.     

Self‐Additive Low‐Dimensional Ruddlesden–Popper Perovskite by the Incorporation of Glycine Hydrochloride for High‐Performance and Stable Solar Cells

The recent rise of low‐dimensional Ruddlesden–Popper (RP) perovskites is notable for superior humidity stability, however they suffer from low power conversion efficiency (PCE). Suitable organic spacer cations with special properties display a critical effect on the performance and stability of perovskite solar cells (PSCs). Herein, a new strategy of designing self‐additive low‐dimensional RP perovskites is first proposed by employing a glycine salt (Gly⁺) with outstanding additive effect to improve the photovoltaic performance. Due to the strong interaction between C?O and Pb²⁺, the Gly⁺ can become a nucleation center and be beneficial to uniform and fast growth of the Gly‐based RP perovskites with larger grain sizes, leading to reduced grain boundary and increased carrier transport. As a result, the Gly‐based self‐additive low‐dimensional RP perovskites exhibit remarkable photoelectric properties, yielding the highest PCE of 18.06% for Gly (n = 8) devices and 15.61% for Gly (n = 4) devices with negligible hysteresis. Furthermore, the Gly‐based devices without encapsulation show excellent long‐term stability against humidity, heat, and UV light in comparison to BA‐based low‐dimensional PSCs. This approach provides a feasible design strategy of new‐type low‐dimensional RP perovskites to obtain highly efficient and stable devices for next‐generation photovoltaic applications.     

Production of Flexible Transparent Conducting Films of Self‐Fused Nanowires via One‐Step Supersonic Spraying

Scalable and economical manufacturing of flexible transparent conducting films (TCF) is a key barrier to widespread adoption of low‐cost flexible electronics. Here, a simple, robust, and scalable method of flexible TCF formation using supersonic kinetic spraying is demonstrated. Silver nanowire (AgNW) suspensions are sprayed at supersonic speed to produce self‐sintered films of AgNWs on flexible substrates. These films display remarkably low sheet resistance, <10 Ω sq^?1, combined with high transmittance, >90%. These electrically conducting, transparent, and flexible coatings can be deposited over a 100 cm² area in ≈30 s. Theoretical analysis reveals the underlying physical mechanism behind self‐sintering, showing that self‐sintering is enabled by the high velocity of impact in supersonic spraying.     

Nanoweb Formation: 2D Self‐Assembly of Semiconductor Gallium Oxide Nanowires/Nanotubes

This paper reports a method to produce networks of crystalline gallium oxide comprised of one‐dimensional (1D) nanostructures. Because of the unique arrangement of wires, these crystalline networks are termed as ‘nanowebs’. Nanowebs are of great technological interest since they contain wire densities of the order of 10⁹ cm^–2. A possible mechanism for the fast self‐assembly of crystalline metal oxide nanowires involves multiple nucleation and coalescence via oxidation–reduction reactions at the molecular level. The preferential growth of nanowires parallel to the substrate enabled them to coalesce into regular polygonal networks. The individual segments of the polygonal network consist of both nanowires and nanotubules of β‐gallium oxide. Individual wire properties contribute to a nanoweb’s overall capacity and the implications for devices based on nanowebs are expected to be enormous.     

Chem‐Bonding and Phys‐Trapping Se Electrode for Long‐Life Rechargeable Batteries

Selenium‐carbon materials present an interesting opportunity for rechargeable battery systems. They are usually obtained through infusing elemental Se into various carbon sources. Herein, a self‐thermal‐reduction method is successfully applied to prepare covalent Se carbon material (CPSe, Se: 10.8 wt%) utilizing polyselenophene (PSe) as a dual source of selenium and carbon matrix, in which selenium is mainly present with the form of C? Se bond. Interestingly, most of them are found to break away from the carbon skeleton as the discharge voltage is gradually scanned down to a lower stage, and then selenide is progressively oxidized to elemental Se in the charge process. Furthermore, employing a space‐confined strategy, a high Se mass loading composite (Se‐CPSe, 56.8 wt%) is effectively produced with the simultaneous introduction of covalent Se and physical‐trapped Se. In this electrode, the physical‐restricted Se part exhibits a reversible capacity of 420 mA h g^?1 at 100 mA g^?1 for the Na‐Se battery. More significantly, after being activated at 0.01–3.0 V in the initial cycles, the electrochemical cleaved covalent Se and physical‐confined Se can jointly contribute specific capacity of ≈590 mA h g^?1. Such strategies and understanding are important for the future design and optimization of electrode materials for Na‐Se batteries.     

Nanogap Plasmonic Structures Fabricated by Switchable Capillary‐Force Driven Self‐Assembly for Localized Sensing of Anticancer Medicines with Microfluidic SERS

Nanogap plasmonic structures, which can strongly enhance electromagnetic fields, enable widespread applications in surface‐enhanced Raman spectroscopy (SERS) sensing. Although the directed self‐assembly strategy has been adopted for the fabrication of micro/nanostructures on open surfaces, fabrication of nanogap plasmonic structures on complex substrates or at designated locations still remains a grand challenge. Here, a switchable self‐assembly method is developed to manufacture 3D nanogap plasmonic structures by combining supercritical drying and capillary‐force driven self‐assembly (CFSA) of micropillars fabricated by laser printing. The polymer pillars can stay upright during solvent development via supercritical drying, and then can form the nanogap after metal coating and subsequent CFSA. Due to the excellent flexibility of this method, diverse patterned plasmonic nanogap structures can be fabricated on planar or nonplanar substrates for SERS. The measured SERS signals of different patterned nanogaps in fluidic environment show a maximum enhancement factor ≈8 × 10⁷. Such nanostructures in microchannels also allow localized sensing for anticancer drugs (doxorubicin). Resulting from the marriage of top‐down and self‐assembly techniques, this method provides a facile, effective, and controllable approach for creating nanogap enabled SERS devices in fluidic channels, and hence can advance applications in precision medicine.     

A Flexible Dual‐Ion Battery Based on Sodium‐Ion Quasi‐Solid‐State Electrolyte with Long Cycling Life

Sodium‐based dual‐ion batteries (SDIBs) have attracted much attention for their advantages of high operating voltage, environmental friendliness, and especially low cost. However, the electrochemical performances of the reported SDIBs are still unsatisfied due to the decomposition problem of traditional liquid electrolyte under high working voltage. Development of quasi‐solid‐state electrolytes (QSSEs) with excellent electrochemical stability at high voltage is a possible means to improve their properties. In this work, a flexible SDIB based on a QSSE, consisting of poly(vinylidene ?uoride‐co‐hexa?uoropropylene) (PVDF‐HFP) three‐dimensionally cross‐linked with Al₂O₃ nanoparticles, which exhibits a porous 3D structure with dramatically enhanced ionic conductivity up to ≈1.3 × 10^?3 S cm^?1, facilitating fast ionic migration of both anions and cations, is reported. This quasi‐state SDIB exhibits a high specific capacity of 96.8 mAh g^?1 at a current rate of 5 C and excellent cycling stability with a capacity retention of 97.5% after 600 cycles at 5 C, which is the best performance of the SDIBs. Moreover, excellent flexibility and a wide working temperature range (?20 to 70 °C) have been realized for this battery, suggesting its potential for high‐performance flexible energy storage applications.     

Nanodiamond‐Palladium Core–Shell Organohybrid Synthesis: A Mild Vapor‐Phase Procedure Enabling Nanolayering Metal onto Functionalized sp3‐Carbon

A novel approach for the bottom‐up construction of hybrid organic–inorganic nanocomposites with an intimate arrangement between sp³‐carbon 3D molecular‐size nanodiamonds (diamondoids) and a coated palladium surface as nanolayer is reported. The construction process is conducted stepwisely from the gas phase, using first controlled vapor‐phase self‐assembly of tailor‐made functionalized diamantane derivatives, followed by low‐temperature (45 °C) chemical vapor deposition of an organometallic complex in a reducing H₂ atmosphere over the self‐assembled diamondoid scaffold. The use of self‐assemblies of primary diamantane phosphine and phosphine oxide, which are produced with high structural uniformity and reproducibility, yields new hybrid diamondoid‐palladium materials incorporating Pd? O? PH? diamantane bonding motifs. Additional investigations provide evidence for a very challenging issue in the intimate construction of sp³‐C/metal scaffolds. Scanning electron microscopy and transmission electron microscopy microscopies combined with X‐ray photoelectron spectroscopy surface analysis and EDX bulk analysis confirm the formation of diamondoid‐palladium organohybrids with unique surface layering. The vapor phase‐controlled mild synthetic process allows excellent control over nanocomposite formation and morphology from molecular‐level modifications. As such, this bottom‐up composite building process bridges scales from the molecular (functionalized diamondoids) over nanoscopic (self‐assemblies) to microscopic regime (hybrids), in the challenging association of transition metals with an electronically saturated sp³‐carbon organic host material.     

Programmed High‐Hole‐Mobility Supramolecular Polymers from Disk‐Shaped Molecules

In this paper a simple, casting solution technique for the preparation of two‐dimensional (2D) arrays of very‐high molecular weight (MW) 1D‐Pc supramolecular inorganic polymers is described. The soluble fluoroaluminium tetra‐tert‐butylphthalocyanine (ttbPcAlF) is synthesized and characterized, which can be self‐assembled to form 2D arrays of very‐high‐MW 1D‐Pc supramolecular inorganic polymers. High‐resolution transmission electron microscopy (HRTEM) demonstrates that the 1D‐ttbPcAlF, having a cofacial ring spacing of ～0.36 nm and an interchain distance of ～1.7 nm, self‐assembles into 2D‐nanosheets (～140 nm in length, ～20 nm in width, and equivalent to MW of 3.2 × 10⁵ g mol^?1). The film cast from a 1,2‐dichloroethane (DCE) solution shows a minimum hole‐mobility of ～0.3 cm² V^?1 s^?1 at room temperature by flash‐photolysis time‐resolved microwave conductivity (TRMC) measurements and a fairly high dark dc‐conductivity of ～1 × 10^?3 S cm^?1.     

Phthalocyanine‐Based 2D Conjugated Metal‐Organic Framework Nanosheets for High‐Performance Micro‐Supercapacitors

2D conjugated metal‐organic frameworks (2D c‐MOFs) are emerging as a novel class of conductive redox‐active materials for electrochemical energy storage. However, developing 2D c‐MOFs as flexible thin‐film electrodes have been largely limited, due to the lack of capability of solution‐processing and integration into nanodevices arising from the rigid powder samples by solvothermal synthesis. Here, the synthesis of phthalocyanine‐based 2D c‐MOF (Ni₂[CuPc(NH)₈]) nanosheets through ball milling mechanical exfoliation method are reported. The nanosheets feature with average lateral size of ≈160 nm and mean thickness of ≈7 nm (≈10 layers), and exhibit high crystallinity and chemical stability as well as a p‐type semiconducting behavior with mobility of ≈1.5 cm² V^?1 s^?1 at room temperature. Benefiting from the ultrathin feature, the nanosheets allow high utilization of active sites and facile solution‐processability. Thus, micro‐supercapacitor (MSC) devices are fabricated mixing Ni₂[CuPc(NH)₈] nanosheets with exfoliated graphene, which display outstanding cycling stability and a high areal capacitance up to 18.9 mF cm^?2; the performance surpasses most of the reported conducting polymers‐based and 2D materials‐based MSCs.     

Temperature‐Induced Hydrogels Through Self‐Assembly of Cholesterol‐Substituted Star PEG‐b‐PLLA Copolymers: An Injectable Scaffold for Tissue Engineering

Partially cholesterol‐substituted 8‐arm poly(ethylene glycol)‐block‐poly(L ‐lactide) (8‐arm PEG‐b‐PLLA‐cholesterol) has been prepared as a novel star‐shaped, biodegradable copolymer derivative. The amphiphilic 8‐arm PEG‐b‐PLLA‐cholesterol aqueous solution (polymer concentration, above 3 wt%) exhibits instantaneous temperature‐induced gelation at 34 °C, but the virgin 8‐arm PEG‐b‐PLLA does not, irrespective of concentration. Moreover, an extracellular matrix (ECM)‐like micrometer‐scale network structure has been created with favorable porosity for three‐dimensional proliferation of cells inside the hydrogel. This network structure is mainly attributed to specific self‐assembly between cholesterol groups. The 10 and 20 wt% hydrogels are eroded gradually in phosphate buffered saline at 37 °C over the course of a month, and after that the gel becomes completely dissociated. Moreover, L929 cells encapsulated into the hydrogel are viable and proliferate three‐dimensionally inside the hydrogels. Thus, in‐vitro cell culture studies demonstrate that 8‐arm PEG‐b‐PLLA‐cholesterol is a promising candidate as a novel injectable cellular scaffold.     

Hierarchical Ordered Dual‐Mesoporous Polypyrrole/Graphene Nanosheets as Bi‐Functional Active Materials for High‐Performance Planar Integrated System of Micro‐Supercapacitor and Gas Sensor

Planar integrated systems of micro‐supercapacitors (MSCs) and sensors are of profound importance for 3C electronics, but usually appear poor in compatibility due to the complex connections of device units with multiple mono‐functional materials. Herein, 2D hierarchical ordered dual‐mesoporous polypyrrole/graphene (DM‐PG) nanosheets are developed as bi‐functional active materials for a novel prototype planar integrated system of MSC and NH₃ sensor. Owing to effective coupling of conductive graphene and high‐sensitive pseudocapacitive polypyrrole, well‐defined dual‐mesopores of ≈7 and ≈18 nm, hierarchical mesoporous network, and large surface area of 112 m² g^?1, the resultant DM‐PG nanosheets exhibit extraordinary sensing response to NH₃ as low as 200 ppb, exceptional selectivity toward NH₃ that is much higher than other volatile organic compounds, and outstanding capacitance of 376 F g^?1 at 1 mV s^?1 for supercapacitors, simultaneously surpassing single‐mesoporous and non‐mesoporous counterparts. Importantly, the bi‐functional DM‐PG‐based MSC‐sensor integrated system represents rapid and stable response exposed to 10–40 ppm of NH₃ after only charging for 100 s, remarkable sensitivity of NH₃ detection that is close to DM‐PG‐based MSC‐free sensor, impressive flexibility with ≈82% of initial response value even at 180°, and enhanced overall compatibility, thereby holding great promise for ultrathin, miniaturized, body‐attachable, and portable detection of NH₃.     

Cactus‐Like NiCoP/NiCo‐OH 3D Architecture with Tunable Composition for High‐Performance Electrochemical Capacitors

To effectively enhance the energy density and overall performance of electrochemical capacitors (ECs), a new strategy is demonstrated to increase both the intrinsic activity of the reaction sites and their density. Herein, nickel cobalt phosphides (NiCoP) with high activity and nickel cobalt hydroxides (NiCo‐OH) with good stability are purposely combined in a hierarchical cactus‐like structure. The hierarchical electrode integrates the advantages of 1D nanospines for effective charge transport, 2D nanoflakes for mechanical stability, and 3D carbon cloth substrate for flexibility. The NiCoP/NiCo‐OH 3D electrode delivers a high specific capacitance of ≈1100 F g^?1, which is around seven times higher than that of bare NiCo‐OH. It also possesses ≈90% capacitance retention after 1000 charge–discharge cycles. An asymmetric supercapacitor composed of NiCoP/NiCo‐OH cathode and metal–organic framework‐derived porous carbon anode achieves a specific capacitance of ≈100 F g^?1, high energy density of ≈34 Wh kg^?1, and excellent cycling stability. The cactus‐like NiCoP/NiCo‐OH 3D electrode presents a great potential for ECs and is promising for other functional applications such as catalysts and batteries.     

Non‐Covalent Functionalization of Graphene Using Self‐Assembly of Alkane‐Amines

A simple, versatile method for non‐covalent functionalization of graphene based on solution‐phase assembly of alkane‐amine layers is presented. Second‐order Møller–Plesset (MP2) perturbation theory on a cluster model (methylamine on pyrene) yields a binding energy of ≈220 meV for the amine–graphene interaction, which is strong enough to enable formation of a stable aminodecane layer at room temperature. Atomistic molecular dynamics simulations on an assembly of 1‐aminodecane molecules indicate that a self‐assembled monolayer can form, with the alkane chains oriented perpendicular to the graphene basal plane. The calculated monolayer height (≈1.7 nm) is in good agreement with atomic force microscopy data acquired for graphene functionalized with 1‐aminodecane, which yield a continuous layer with mean thickness ≈1.7 nm, albeit with some island defects. Raman data also confirm that self‐assembly of alkane‐amines is a non‐covalent process, i.e., it does not perturb the sp² hybridization of the graphene. Passivation and adsorbate n‐doping of graphene field‐effect devices using 1‐aminodecane, as well as high‐density binding of plasmonic metal nanoparticles and seeded atomic layer deposition of inorganic dielectrics using 1,10‐diaminodecane are also reported.     

Universal Surfactant‐Free Strategy for Self‐Standing 3D Tremella‐Like Pd–M (M = Ag,Pb, and Au) Nanosheets for Superior Alcohols Electrocatalysis

Pd‐based nanosheet materials have emerged as efficient catalysts for monobasic and polyhydric alcohol oxidation reactions. However, most reported synthetic methods of Pd‐based nanosheets (NSs) are nonuniversal and surfactant‐involved, leading to residue‐covered surfaces with drastically damaged electrocatalytic properties. Herein, a universal, surfactant‐free, simple one‐pot route is developed for the precise synthesis of a kind of novel self‐standing Pd–M (M = Ag, Pb, Au, Ga, Cu, Pt, etc.) NSs with tremella‐like superstructures are assembled using ultrathin two‐dimensional (2D) NSs. Benefiting from the universal surfactant‐free methods, the obtained Pd–M NSs exhibit clean surfaces and stable three‐dimensional (3D) self‐standing structures that overcome the difficulty of normal close packing and overlapping 2D NSs. The Pd–M (M = Ag, Pb, and Au) NSs with tremella‐like structures all show excellent ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR) properties. In particular, with the optimal superstructure, better electronic effect, and promoted toxicity tolerance, the EOR/EGOR mass activities of Pd₇Ag NSs, Pd₇Pb NSs, and Pd₇Au NSs are 8.2/7.3, 7.2/5.7, and 5.3/4.4 times higher than that of commercial Pd/C catalysts. This advanced 3D construction also endows Pd–M NSs with more favorable stability than Pd/C. This study may be extended to Pd–M (M = other metals) NSs and open up more opportunities for broad catalytic applications.     

Cover Picture: Fabrication of Multicomponent Microsystems by Directed Three‐Dimensional Self‐Assembly (Adv. Funct. Mater. 5/2005)

Directed three‐dimensional self‐assembly to assemble and package integrated semiconductor devices is demonstrated by Jacobs and Zheng on p. 732. The self‐assembly process uses geometrical shape recognition to identify different components and surface‐tension between liquid solder and metal‐coated areas to form mechanical and electrical connections.The components (top left) self‐assemble in a turbulent flow (center) and form functional multi‐component microsystems (bottom right) by sequentially adding parts to the assembly solution. The technique provides, for the first time, a route to enable the realization of three‐dimensional heterogeneous microsystems that contain non‐identical parts, and connecting them electrically. We have developed a directed self‐assembly process for the fabrication of three‐dimensional (3D) microsystems that contain non‐identical parts and a statistical model that relates the process yield to the process parameters. The self‐assembly process uses geometric‐shape recognition to identify different components, and surface tension between liquid solder and metal‐coated areas to form mechanical and electrical connections. The concept is used to realize self‐packaging microsystems that contain non‐identical subunits. To enable the realization of microsystems that contain more than two non‐identical subunits, sequential self‐assembly is introduced, a process that is similar to the formation of heterodimers, heterotrimers, and higher aggregates found in nature, chemistry, and chemical biology. The self‐assembly of three‐component assemblies is demonstrated by sequentially adding device segments to the assembly solution including two hundred micrometer‐sized light‐emitting diodes (LEDs) and complementary metal oxide semiconductor (CMOS) integrated circuits. Six hundred AlGaInP/GaAs LED segments self‐assembled onto device carriers in two minutes, without defects, and encapsulation units self‐assembled onto the LED‐carrier assemblies to form a 3D circuit path to operate the final device. The self‐assembly process is a well‐defined statistical process. The process follows a first‐order, non‐linear differential equation. The presented model relates the progression of the self‐assembly and yield with the process parameters—component population and capture probability—that are defined by the agitation and the component design.     

High‐Energy Asymmetric Supercapacitor Yarns for Self‐Charging Power Textiles

Rapid growth of electronic textile increases the demand for textile‐based power sources, which should have comparable lightweight, flexibility, and comfort. In this work, a self‐charging power textile interwoven by all‐yarn‐based energy‐harvesting triboelectric nanogenerators (TENG) and energy‐storing yarn‐type asymmetric supercapacitors (Y‐ASC) is reported. Common polyester yarns with conformal Ni/Cu coating are utilized as 1D current collectors in Y‐ASCs and electrodes in TENGs. The solid‐state Y‐ASC achieves high areal energy density (≈78.1 µWh cm^?2), high power density (14 mW cm^?2), stable cycling performance (82.7% for 5000 cycles), and excellent flexibility (1000 cycles bending for 180°). The TENG yarn can be woven into common fabrics with desired stylish designs to harvest energy from human daily motions at high output (≈60 V open‐circuit voltage and ≈3 µA short‐circuit current). The integrated self‐charging power textile is demonstrated to power an electronic watch without extra recharging by other power sources, suggesting its promising applications in electronic textiles and wearable electronics.     

Co‐Interlayer Engineering toward Efficient Green Quasi‐Two‐Dimensional Perovskite Light‐Emitting Diodes

With respect to three‐dimensional (3D) perovskites, quasi‐two‐dimensional (quasi‐2D) perovskites have unique advantages in light‐emitting devices (LEDs), such as strong exciton binding energy and good phase stability. Interlayer ligand engineering is a key issue to endow them with these properties. Rational design principles for interlayer materials and their processing techniques remain open to investigation. A co‐interlayer engineering strategy is developed to give efficient quasi‐2D perovskites by employing phenylbutylammonium bromide (PBABr) and propylammonium bromide (PABr) as the ligand materials. Preparation of these co‐interlayer quasi‐2D perovskite films is simple and highly controllable without using antisolvent treatment. Crystallization and morphology are readily manipulated by tuning the ratio of co‐interlayer components. Various optical techniques, including steady and ultrafast transient absorption and photoluminescence spectroscopies, are used to investigate their excitonic properties. Photoluminescence quantum yield (PLQY) of the perovskite film is dramatically improved to 89% due to the combined optimization of exciton binding energy and suppression of trap state formation. Accordingly, a high current efficiency of 66.1 cd A^?1 and an external quantum efficiency of 15.1% are achieved for green co‐interlayer quasi‐2D perovskite LEDs without using any light out‐coupling techniques, indicating that co‐interlayer engineering is a simple and effective approach to develop high‐performance perovskite electroluminescence devices.