Organic Electrochemical Transistors

A dual ionic transport property of self-doped conjugated polyelectrolytes is reported by Thuc-Quyen Nguyen and co-workers in article number 2200274: they can be both doped and dedoped upon the interaction with anions (blue) and cations (red) in an electrolyte, respectively. This discovery enables dual-mode organic electrochemical transistors, paving the way for the use of organic devices in emerging reconfigurable electronics.

Liquid Crystals

Liquid-crystalline assemblies of a variety of molecules forming 1D, 2D, and 3D structures lead to new functions. Recent advances in functional liquid-crystalline materials based on polymers, supramolecular complexes, gels, colloids, and inorganic-based hybrids are highlighted by Takashi Kato and co-workers in article number 2109063. Design strategies, advanced measurements, computational simulations, and functionalization of these materials and interfaces are discussed.

Dendrimer Emitters

In article number 2110344, Dianming Sun, Xiaohong Zhang, Anna Köhler, Eli Zysman-Colman, and co-workers report the rational design of thermally activated delayed fluorescence (TADF) dendrimer emitters that show remarkable photophysical properties, resolving the conflicting requirements of achieving simultaneously a small activation energy and a large oscillator strength. Their use in a host-free solution-processed organic light-emitting diode (OLED), which shows record-high external quantum efficiencies, is demonstrated. The dendrimer design strategy provides a route to high-performance solution-processed TADF OLEDs and evidences the full potential of dendrimers as emissive materials.

Biohybrid Robots

The next robotics frontier will be led by biohybrids, robots that incorporate living biological cells and tissue, which are addressed by Miriam Filippi, Robert K. Katzschmann, and co-workers in article number 2108427. Microfluidics substantially contributes to the development of biological tissue in vitro, as microfluidic flow control enables fluid regulation at the microscale and fine tissue structuring during biofabrication. Microfluidics will advance the co-assembly, scale-up, and integration of biohybrid robots, and make these robots performant and functional for real-world use.

2D MBenes, early transition metal borides, have recently gained tremendous attention due to their unique properties. This Perspective sheds light on the material–structure–property relationship of MBenes and elucidates the most prospective applications in various fields, thus opening a promising paradigm for designing new functional systems and high-performance devices with multipurpose functionalities.

Engineering atomically dispersed single metal site catalysts in surface functionalization, coordination environments, and local carbon structures can effectively tune two-electron oxygen-reduction pathways for efficient hydrogen peroxide production. The review summarizes recent progress on catalyst development and electrode design to electrolyzer fabrication for clean and sustainable hydrogen peroxide electrosynthesis.

Microfluidics enables the engineering of biological tissues through micro-precision control over the cell microenvironment, fabrication of cell-laden matrices, and distribution of fluids to perfuse 3D tissue constructs. In particular, microfluidically-advanced functional muscle tissues can be used as performant actuators in the next generation of bio-hybrid robots.

Aqueous rechargeable zinc-iodine batteries (ZIBs), including zinc-iodine redox flow batteries and static ZIBs, are promising candidates for future grid-scale electrochemical energy storage. This article reviews the electrochemistry in ZIBs, discusses their fundamental questions, and highlights the key strategies and recent accomplishments in tackling the challenges. This review also provides perspectives on the future research development of ZIBs.

Bioelectronics has been exhibiting its positive impact on the quality improvement of human life. Especially, unique characteristic advantages of conductive materials with elaborate micro/nanostructures have facilitated the development of high-performance bioelectronic devices. The fabrication, properties, promising applications, future opportunities, as well as challenges of conductive materials with micro/nanostructures in bioelectronics, are comprehensively summarized.

Although the research of 2D photocatalysts has made great progress in the past decades, there are still many challenges in understanding the deep relationship between the surface state and the reaction mechanism. The surface modification strategies and reaction mechanisms of 2D photocatalysts are reviewed, and some useful views are put forward for future research in this field.

With PCPDTBT-SO3K (CPE-K) as the active material, dual-mode organic electrochemical transistors that operate in both depletion mode and enhancement mode are demonstrated. Mode switching is done via changing the polarity of the applied voltages, enabled by the dual-mode absorption capabilities of CPE-K. These transistors are used to create reconfigurable logic gates, paving the way for the use of organic electrochemical transistors in emerging reconfigurable electronics.

The rational design of a donor–acceptor dendrimer emitter that shows remarkable photophysical properties, including efficient thermally activated delayed fluorescence (TADF) and high photoluminescence quantum yield, is reported. Its use is demonstrated in a host-free solution-processed organic light-emitting diode (OLED) that shows record-high external quantum efficiencies.

Lead Telluride Nanoparticles

Lead telluride nanoparticles spontaneously assemble into a spanning nanofiber network as reported by Nicholas A. Kotov and co-workers in article number 2201313. The resulting transparent nanoparticle hydrogels have potential application as UV or X-ray sensors. The network morphology can be modified through variations in the composition and concentration of added electrolyte. Evaluation of the network morphology with graph theory is used to derive correlations to the gels' mechanical and electrical properties.

Hydrogels of lead telluride nanoparticles are structurally characterized using graph theory. The morphology of the gels is quantified, identifying the effect of various salt concentrations and compositions on the connectivity of the network structures. Significant influence by divalent cations on gel structure is observed. Relationships between the structural descriptors and viscoelastic and charge transport properties are evaluated.

Negative Phototransistors

In article number 2201364, Huipeng Chen, Jishan Wu, Fangxu Yang, Wenping Hu, and co-workers report an ultrasensitive negative phototransistor based on 1D/2D molecular crystal p–n heterojunctions. This novel device exhibits a variety of intriguing properties, including superior performance parameters, accurately controllable threshold voltage, and ultrasensitive detection of weak light. The results demonstrate the fascinating promise of organic single-crystal heterostructure electronics.

Ultrasensitive negative phototransistors are developed based on 1D/2D molecular crystal (1D/2DMC) p–n heterojunctions. This unique structure utilizes photogenerated holes of p-type 1DMCs to dope electron carriers in n-type 2DMC channels under UV illumination, achieving complete depletion of the channel current. The negative phototransistor exhibits superior performance parameters, accurately controllable threshold voltage by light, and ultrasensitive detection of weak light.

A planar polariton focusing device based on the natural in-plane hyperbolic van der Waals material α-MoO₃ is developed, which achieves ultrahigh field compression and wide-range tunable performance. Moreover, a graphene/α-MoO₃ heterostructure is constructed, which supports hybrid modes consisting of α-MoO₃ phonon polaritons and graphene plasmons to achieve in situ dynamical control of the focal length.

The mixed-valence strategy and construction of an “all in one” electrode is employed to prepare flexible carbon fiber cloth supported porous Co_xP hierarchical structures comprising nanoneedles and nanosheets. The as-prepared Co_x[email protected] electrode exhibits enhanced sodium-storage performance with a high reversible capacity (814 mAh g⁻¹), remarkable rate performance (279 mAh g⁻¹ at 5.0 A g⁻¹), and record ultralong cycling life (almost 100% capacity retention after 9000 cycles).

Chiral domain walls are moved with current pulses highly efficiently along synthetic antiferromagnetic racetracks formed on thin underlayers of several 5d-Al alloys. These alloys exhibit very large spin Hall angles of up to ≈1.0 and, moreover, template [001] oriented Co–Ni multilayers with high perpendicular magnetic anisotropy, making them highly useful for racetrack memories compatible with complementary metal–oxide–semiconductor technologies.

Self-adaptive platelet pharmacytes, consisting of encapsulated Rab27a siRNA nanocomplexes and backpacked anti-PD-L1 nanogels, are engineered to hierarchically amplify antitumor immunity. The platelet pharmacytes efficiently silence Rab27a in tumor cells to inhibit secretion of tumor-derived exosomes, which relieves the immunosuppression and cascadingly releases anti-PD-L1 to sensitize anti-PD-L1-mediated immune checkpoint blockade.

The density of Li metal is low, so the abuse of Li foil in Li-metal batteries (LMBs) can easily lead to the loss of their advantage in volumetric energy density over Li-ion batteries. In addition, Li plating on a Li substrate is not as dense as that on a Cu substrate. Therefore, anode-free LMBs are more worthy of recommendation.

A composite films system consisting of ferroelectric material and dielectric film is proposed as a memristor medium to improve the comprehensive performances of the resistive-switching behavior, and epitaxial BaTiO₃−CeO₂ ferroelectric films on silicon are obtained successfully. The durability of the device is more than 10⁹ cycles, and the speed can be lower than 10 ns.

A facile and universal concept of hydrogen-bond-assisted solution discharge in aprotic Li–O₂ batteries is proposed, and 2,5-di-tert-butylhydroquinone (DBHQ), an antioxidant with hydroxyl groups, is introduced as an exemplary soluble catalyst to promote the solution discharge by hydrogen-bond-assisted solvation of O₂⁻ and Li₂O₂ (OH···O); thus, the Li–O₂ battery with DBHQ delivers an ultrahigh discharge capacity and Li₂O₂ yield.

The transient absorption in monolayers of transition metal dichalcogenides grown on fused silica by the laser-assisted synthesis technique exhibits very unusual decay dynamics that feature long-lived components progressively increasing with the excitation fluence. The experimental observations are interpreted as resulting from the strain-induced modification of the electronic bands and concomitant interplay of the intervalley and intravalley excitons’ populations.

CRISPR-Cas9 may offer new therapeutics for genetic diseases through gene disruption via nonhomologous end joining (NHEJ) or gene correction via homology-directed repair (HDR). In this work, facilely fabricated pH-responsive polymer nanoparticles, capable of safely and efficiently delivering Cas9 ribonucleoprotein alone (NHEJ-NP) or together with donor DNA (HDR-NP), are developed for gene editing in mouse liver, lung, or skeletal muscle.

Long-chain n-heptylamine is introduced via antisolvent engineering into a formamidine (FA)-based perovskite film, which promotes the formation of α-FAPbI₃ at room temperature in humid air via intermolecular exchange behavior. The champion device delivers a power conversion efficiency of 23.7% (certificated 22.76%) with negligible hysteresis and superior stability.

A sustainable, cheap, fast (100 A g⁻¹), stable (1 000 000 cycles), and high-loading (≈50 mg cm⁻²) polymer anode is developed for aqueous Zn-ion batteries and capacitors by engineering both the electrode and electrolyte, surpassing the Zn-metal anode.

Ultrathin CrTe₃ films are successfully synthesized. Monolayer (ML) CrTe₃ represents a unique van der Waals (vdW) magnet with intralayer antiferromagnetism, which is identified by scanning probe microscopy. A facile method is developed to fabricate CrTe₃/CrTe₂ magnetic heterostructures from ML CrTe₃ with an atomically sharp and seamless interface, which is significant for the development of miniaturized spintronic devices based on vdW magnets.

Quantum imaging of spin–orbit-torque-driven magnetic switching and chiral spin rotation in noncollinear antiferromagnet Mn₃Sn films is achieved using nitrogen-vacancy (NV) centers in diamond. Off-resonance dipole–dipole coupling between Mn₃Sn and proximate NV centers is also established, highlighting the significant potential of NV centers in diagnosing the local magnetic properties of emergent quantum materials with vanishingly small magnetic moments.

An automated laser-based synthesis machine is presented, combining laser-induced forward transfer and robotics to perform parallel chemistry in the microarray format with up to 10 000 individual reactions cm⁻². By developing an optimization pipeline, peptide microarrays with thousands of different sequences can be synthesized in high yield to study the antibody responses in infectious disease patients.

An inclusion–sequestration strategy is developed by making use of multicationic supramolecular organic frameworks and porous organic polymers as porous antidotes to neutralize heparins. In vitro and in vivo experiments and biocompatibility evaluations confirm that the porous polymers can realize rapid, safe, and universal reversal of heparin-based anticoagulants, superior to that of clinically used protamine.

A liquid crystal elastomer (LCE) thermoelectric device is reported, which combining active Peltier heating and cooling of LCE, along with environmental and regenerative Seebeck energy harvesting in a 3D printed material architecture. A new method of actuating LCEs, along with a new, more efficient approach to soft robotics, is introduced.

Phase-transfer-catalyzed LiTFSI doping in Spiro-OMeTAD is developed to address the negative impacts of doping-induced hygroscopicity and ion diffusion. Crowning Li⁺ ions in the hole-transporting layer enables perovskite solar cells with enhanced power conversion efficiency and significantly improves stability under humid and thermal conditions.

A material strategy to fabricate a stretchable metallic nanocomposite with strain-insensitive resistance is proposed. When the surface of silver nanomaterials is treated with 1-decanethiol, the nanomaterials self-organize in response to external strain. Adopting the optimum composition of 0D/1D/2D silver nanomaterials enables preservation of the percolation networks, resulting in strain-insensitive resistance of the nanocompsite.

High-quality gallium nitride (GaN)-based heterostructures are epitaxially grown on a 4° off-axis 4H-silicon carbide (SiC) substrate, based on which, state-of-the-art high-electron-mobility transistors are fabricated, suggesting a practical approach to realizing GaN/SiC hybrid field-effect transistors (HyFETs). The distinct two-step biaxial strain relaxation in the III–nitride epilayer is revealed, offering a design guideline of such an unconventional vicinal epitaxy technique.

A high-performance solid-state electrolyte by engineering of the molecular channels in lithiated covalent organic frameworks (COFs) is presented. In situ electrolyte mediation in the COF increases charge-carrier concentration, eliminates interfacial defects, and activates the motion of Li⁺ ions in a directional manner. The COF-based electrolyte demonstrates reliable electrochemical cyclability in pouch cells.

An on-chip liquid metal plug generator is demonstrated. Reproducible liquid metal plugs of a given size are generated based on Laplace pressure tuning in constricted channels whereas plugs of varying sizes and interspacing are generated for modulated voltages in straight channels prefilled with 1 m NaOH. This device can be used to generate liquid metal plugs on demand directly on-chip.

Epidermal growth factor receptor type 2 (HER2) and integrin α_vβ₃ dual-targeted recombinant protein drug conjugate can downregulate the expressions of the HER family including EGFR (HER1), HER2, HER3, and HER4, inhibit the downstream signaling pathways, and improve the drug accumulation and distribution in tumors, leading to reduction of tumor size and significant inhibition of tumor metastasis.

Insight into fiber formation can provide rationale for the design of fibers with programmed mechanical properties. An energy-efficient route to formation of fibers with properties comparable to natural fibers such as wool and coir is reported. This strategy offers a molecular-level understanding of fiber formation under ambient conditions which reduces current required processing energy by two-to-three orders of magnitude.

The pseudo-planar heterojunction strategy is an efficient strategy to improving average visible transmittance (AVT) and power conversion efficiency (PCE) values of semitransparent organic solar cells (ST-OSCs) simultaneously due to the reduction of the optical loss, and the semitransparent devices afford a highest efficiency of 14.62% with a considerable AVT of 20.42%.

Inspired by the significant chromogenic reaction between starch and iodine, the shuttle effect of Zn–I₂ batteries is effectively addressed by using starch, which strongly anchors polyiodide anions due to its unique double-helix structure. Benefiting from this structure confinement, a Coulombic efficiency of almost 100% and an ultralong life of 50 000 cycles are realized in Zn–I₂ batteries.

A polymeric antimicrobial peptides (AMP) carrier that can enhance anticancer efficacy and minimize the potential side effects of AMPs by finely controlling their spatial distribution is reported. By integrating multiple responsive structures at the molecular level, the carrier finely controls the spatial distribution of AMPs in different biological microenvironments, thereby effectively modulating their membranolytic ability.

An acid-in-clay electrolyte is prepared by integrating fast proton carriers in a natural phyllosilicate clay network, ranking top among the solid proton conductors in terms of high proton conductivities, enlarged electrochemical stability window, and reduced chemical reactivity. Benefitting from the above advantages, the acid-in-clay electrolyte can solve two main challenges in proton batteries: gassing and poor cycling performance.