Homogeneous Freestanding Luminescent Perovskite Organogel with Superior Water Stability

Stable, Scalable, and Free-Standing Perovskite Quantum Dots Composite Reinforced by Cellulose Fibers

Perovskite quantum dots (PQDs) have attracted emerging attention as fluorescent and light-absorbing materials for next-generation optoelectronics due to their outstanding properties and cost-efficiency. However, PQD thin film suffers significant instability due to structure and material failures, which hinders their application in flexible and reliable PQD-based advanced wearable devices. Herein, we use commercial cellulose fiber-based filter paper as a substrate to synthesize PQDs in situ and fabricate PQD-paper free-standing flexible composite film. The abundant hydroxy capping ligands of cellulose fibers and the unique dense network structure of the filter paper can facilitate confined crystallization, forming strong interactions between the PQDs and substrate, the unpackaged PQD composite film showed extraordinary stability (>30 days) in the air with high humidity (90%). Meanwhile, the strong interaction between PQDs and paper enables an ultrasimple drop-cast synthesis process with excellent process tolerance, making it customizable and easy to scale up (10 cm in diameter). Due to the uniformly dispersed PQDs on cellulose fibers of the substrate, the composite demonstrates impressive photo-responsive properties. Photodetector (PD) arrays were designed on free-standing PQD paper and flexible graphitic electrodes, and circuits were fabricated by drawing. The PD arrays can work as optical and electrical dual-mode image sensors with incredible bending robustness, enduring up to 100,000 cycles at 180°.

A Universal Approach Toward Intrinsically Flexible All-Inorganic Perovskite-Gel Composites with Full-Color Luminescence

The combination of all-inorganic perovskites (PVSKs) and polymers allows for free-standing flexible optoelectronic devices. However, solubility difference of the PVSK precursors and concerns over the compatibility between polymer carriers and PVSKs imply a great challenge to incorporate different kinds of PVSKs into polymer matrices by the same manufacturing process. In this work, PVSK precursors are introduced into poly(2-hydroxyethyl acrylate) (PHEA) hydrogels in sequence, in which the PVSK-gel composites are achieved with full-color emissions by simply varying the precursor species. Moreover, it is found that CsBr has a higher interaction energy with the (111) plane of CsPbBr3 than the (110) plane; thus, the CsPbBr3 crystals with a shape of truncated cube and tetragon are observed during the CsPbBr3-Cs4PbBr6 phase transition over time. The PVSK-gel composites feature excellent bendability, elasticity, and stretchable deformation (tensile strain > 500%), which allows for 3D printing emissive customized stereoscopic architectures with shape-memory features.

A bio-inspired co-simulation crawling robot enabled by a carbon dot-doped dielectric elastomer

Flexible actuation materials play a crucial role in biomimetic robots. Seeking methods to enhance actuation and functionality is one of the directions in which actuators strive to meet the high-performance and diverse requirements of environmental conditions. Herein, by utilizing the method of adsorbing N-doped carbon dots (NCDs) onto SiO2 to form clusters of functional particles, a NCDs@SiO2/PDMS elastomer was prepared and its combined optical and electrical co-stimulation properties were effectively harnessed to develop a biomimetic crawling robot resembling Rhagophthalmus (firefly). The introduction of NCDs@SiO2 cluster particles not only effectively improves the mechanical and dielectric properties of the elastomer but also exhibits fluorescence response and actuation response under the co-stimulation of UV and electricity, respectively. Additionally, a hybrid dielectric elastomer actuator (DEA) with a transparent SWCNT mesh electrode exhibits two notable advancements: an 826% increase in out-of-plane displacement under low electric field stimulation compared to the pure matrix and the ability of NCDs to maintain a stable excited state within the polymer for an extended duration under UV-excitation. Simultaneously, the transparent biomimetic crawling robot can stealthily move in specific environments and fluoresce under UV light.

Advancing high-performance tailored dual-crosslinking network organo-hydrogel flexible device for wireless wearable sensing

Conductive hydrogels are essential for enabling long-term and reliable signal sensing in wearable electronics due to their tunable flexibility, stimulus responsiveness, and multimodal sensing integration. However, developing durable and dependable integrated hydrogel-based flexible devices has been challenging due to mismatched mechanical properties, limited water retention capability, and reduced flexibility. This work addresses these challenges by employing a tailored physical-chemical dual-crosslinking strategy to fabricate dynamically reversible organo-hydrogels with high performance. The resultant organo-hydrogels exhibit exceptional characteristics, including high stretchability (up to ∼495% strain), remarkable toughness (with tensile and compressive strengths of ∼1350 kPa and ∼9370 kPa, respectively), and outstanding transparency (∼90.3%). Moreover, they demonstrate excellent long-term water retention ability (>2424 h, >97%). Notably, the organo-hydrogel based sensor exhibits heightened sensitivity for monitoring physiological signals and motions. Furthermore, our integrated wireless wearable sensing system efficiently captures and transmits various human physiological signals and motion information in real-time. This research advances the development of customized devices utilizing functional organo-hydrogel materials, making contributions to fulfilling the increasing demand for high-performance wireless wearable sensing.

Robust Organogel Scintillator for Self-healing and Ultra-flexible X-ray Imaging

Metal halide scintillators serve as promising candidates for X-ray detection due to their high attenuation coefficients, high light yields, and low-cost solution-processable characteristics. However, the issues of humidity/thermal quenching and mechanical fragility, remain obstacles to the broad and diversified development of metal halide scintillators. Here, this work reports a lead-free, water-stable, stretchable, and self-healing (ethylenebis-triphenylphosphonium manganese (II) bromide (C38 H34 P2 )MnBr4 organogel scintillator that meets X-ray imaging in complex scenarios. The robust organogel scintillator can be stretched with elongation up to 1300% while maintaining the scintillation properties. Activated by the dynamic hydrogen bonds and coordination bonds design, the organogel scintillator exhibits excellent self-healing properties at room temperature to alleviate the vignetting problem of the rigid scintillator films, the X-ray imaging resolution can reach 16.7 lp mm-1 . The organogel scintillator can also realize flexible and self-healing X-ray imaging in water, providing a design path for portable devices in harsh conditions.

A Novel Strategy for the Synthesis of High Stability of Luminescent Zero Dimensional-Two Dimensional CsPbBr3 Quantum Dot/1,4-bis(4-methylstyryl)benzene Nanoplate Heterostructures at an Atmospheric Condition

Perovskite quantum dots (QDs), emerging with excellent bright-green photoluminescence (PL) and a large absorption coefficient, are of great potential for the fabrication of light sources in underwater optical wireless communication systems. However, the instability caused by low formation energy and abundant surface traps is still a major concern for perovskite-based light sources in underwater conditions. Herein, we propose ultra-stable zero dimensional-two dimensional (0D-2D) CsPbBr3 QD/1,4-bis(4-methylstyryl)benzene (p-MSB) nanoplate (NP) heterostructures synthesized via a facile approach at room temperature in air. CsPbBr3 QDs can naturally nucleate on the p-MSB NP toluene solution, and the radiative combination is drastically intensified owing to the electron transfer within the typical type-II heterostructures, leading to a sharply increased PLQY of the heterostructure thin films up to 200% compared with the pristine sample. The passivation of defects within CsPbBr3 QDs can be effectively realized with the existence of p-MSB NPs, and thus the obviously improved PL is steadily witnessed in an ambient atmosphere and thermal environment. Meanwhile, the enhanced humidity stability and a peak EQE of 9.67% suggests a synergetic strategy for concurrently addressing the knotty problems on unsatisfied luminous efficiency and stability of perovskites for high-performance green-emitting optoelectronic devices in underwater applications.

Design of mechanical-robust phosphorescence materials through covalent click reaction

It remains a great challenge to engineer materials with strong and stable interactions for the simultaneously mechanical-robust and room temperature phosphorescence-efficient materials. In this work, we demonstrate a covalent cross-linking strategy to engineer mechanical-robust room temperature phosphorescence materials through the B-O click reaction between chromophores, polyvinyl alcohol matrix and inorganic layered double hydroxide nanosheets. Through the covalent cross-linkage between the organic polyvinyl alcohol and inorganic layered double hydroxide, a polymeric composite with ultralong lifetime up to 1.45 s is acquired based on the inhibited non-radiative transition of chromophores. Simultaneously, decent mechanical strength of 97.9 MPa can be realized for the composite materials due to the dissipated loading stress through the covalent-bond-accommodated interfacial interaction. These cross-linked composites also exhibit flexibility, processability, scalability and phosphorescence responses towards the mechanical deformation. It is anticipated that the proposed covalent click reaction could provide a platform for the design and modulation of composites with multi-functionality and long-term durability.

Mechanical tough and multicolor aggregation-induced emissive polymeric hydrogels for fluorescent patterning

Aggregation-induced emissive fluorogens (AIEgens) are promising building blocks for fluorescent polymeric hydrogels (FPHs) because intense fluorescence intensities are usually guaranteed by spontaneous aggregates of hydrophobic AIEgens in a hydrophilic polymer network. However, most AIE-active FPHs are single-color fluorescent and cannot display tunable emission colors. Additionally, efforts to produce mechanically strong AIE-active hydrogels have been largely ignored, restricting their potential uses. Herein, we present the synthesis of an AIE-active methyl picolinate-substituted 1,8-naphthalimide monomer (MP-NI) for fabricating mechanical tough and multicolor FPHs. Owing to the introduction of bulky and coordinative methyl picolinate group, these specially designed MP-NI molecules were forced to adopt propeller-shaped conformation that renders them with intense aggregation-induced blue emission. Moreover, the MP-NI moieties grafted in a hydrogel matrix can sensitize red and green fluorescence of Eu³⁺and Tb³⁺ via antenna effect. Consequently, multicolor fluorescent hydrogels that sustain a high stress of 1 MPa were obtained by chemically introducing MP-NI moieties into dually cross-linked alginate polymer networks with high-density metal (Ca²⁺/Tb³⁺/Eu³⁺) coordination and hydrogen bonding crosslinks. Their capacity to enable the writing of arbitrary multicolor fluorescent patterns using Eu³⁺/Tb³⁺ as inks were finally demonstrated, suggesting their potential uses for smart display and information encryption.

Large-area waterproof and durable perovskite luminescent textiles

Lead halide perovskites show great potential to be used in wearable optoelectronics. However, obstacles for real applications lie in their instability under light, moisture and temperature stress, noxious lead ions leakage and difficulties in fabricating uniform luminescent textiles at large scale and high production rates. Overcoming these obstacles, we report simple, high-throughput electrospinning of large-area (> 375 cm²) flexible perovskite luminescent textiles woven by ultra-stable polymer@perovskite@cyclodextrin@silane composite fibers. These textiles exhibit bright and narrow-band photoluminescence (a photoluminescence quantum yield of 49.7%, full-width at half-maximum <17 nm) and the time to reach 50% photoluminescence of 14,193 h under ambient conditions, showcasing good stability against water immersion (> 3300 h), ultraviolet irradiation, high temperatures (up to 250 °C) and pressure surge (up to 30 MPa). The waterproof PLTs withstood fierce water scouring without any detectable leaching of lead ions. These low-cost and scalable woven PLTs enable breakthrough application in marine rescue.

3D-Printed Janus Piezoelectric Patches for Sonodynamic Bacteria Elimination and Wound Healing

Management of infected wounds has raised worldwide concerns. Attempts in this field focus on the development of intelligent patches for improving the wound healing. Here, inspired by the cocktail treatment and combinational therapy stratagem, we present a novel Janus piezoelectric hydrogel patch via 3-dimensional printing for sonodynamic bacteria elimination and wound healing. The top layer of the printed patch was poly(ethylene glycol) diacrylate hydrogel with gold-nanoparticle-decorated tetragonal barium titanate encapsulation, which realizes the ultrasound-triggered release of reactive oxygen species without leaking nanomaterials. The bottom layer is fabricated with methacrylate gelatin and carries growth factors for the cell proliferation and tissue reconstruction. Based on these features, we have demonstrated in vivo that the Janus piezoelectric hydrogel patch can exert substantial infection elimination activity under the excitation of ultrasound, and its sustained release of growth factors can promote tissue regeneration during wound management. These results indicated that the proposed Janus piezoelectric hydrogel patch had practical significance in sonodynamic infection alleviation and programmable wound healing for treating different clinical diseases.

Recent Advances in Printable Flexible Optical Devices: From Printing Technology and Optimization Strategies to Perspectives

Recently, flexible optical devices have triggered booming developments in various research fields, including display equipment, sensors, energy conversion, and so on, due to their high compatibility, portability, and wearability. With the advantages of strong design ability, high precision, and high integration, printing technologies have been recognized as promising methods to realize flexible optical devices. In this Perspective, recent progress on printing strategies for fabricating flexible optical devices are introduced systematically. First, through adjusting the composition of inks, selecting flexible substrates, and controlling external stimulation, fabrication of flexible optical devices based on inkjet printing is illustrated. Then, flexible optical devices fabricated by template-induced printing, 3D printing, slot-die printing, and screen printing are summarized. Finally, prospects and future development directions based on printing technology for flexible optical devices are proposed.

Materials development in stretchable iontronics

Stretchable iontronics have recently been developed as an ideal interface to promote the interaction between humans and devices. Since the materials that use ions as charge carriers are typically transparent and stretchable, they have been used to fabricate devices with diverse functions with intrinsic transparency and stretchability. With the development of device design, material design has also been investigated to mitigate the issues associated with ionic materials, such as their weak mechanical properties, poor electrical properties, or poor environmental stabilities. In this review, we describe the recent progress on the design of materials in stretchable iontronics. By classifying stretchable ionic materials into three types of components (ionic conductors, ionic semiconductors, and ionic insulators), the issues each component has and the strategies to solve them are introduced, specifically in terms of molecular interactions. We then discuss the existing hurdles and challenges to be handled and shine light on the possibilities and opportunities from the insight of molecular interactions.

Tough, stable and self-healing luminescent perovskite-polymer matrix applicable to all harsh aquatic environments

Gelatinous underwater invertebrates such as jellyfish have organs that are transparent, luminescent and self-healing, which allow the creatures to navigate, camouflage themselves and, indeed, survive in aquatic environments. Artificial luminescent materials that can mimic such functionality can be used to develop aquatic wearable/stretchable displays and water-resistant devices. Here, a luminescent composite that is simultaneously transparent, tough and can autonomously self-heal in both dry and wet conditions is reported. A tough, self-healable fluorine elastomer with dipole–dipole interactions is synthesized as the polymer matrix. It exhibits excellent compatibility with metal halide perovskite quantum dots. The composite possesses a toughness of 19 MJ m−3, maximum strain of 1300% and capability to autonomously self-heal underwater. Notably, the material can withstand extremely harsh aqueous conditions, such as highly salty, acidic (pH = 1) and basic (pH = 13) environment for more than several months with almost no decay in mechanical performance or optical properties.

Investigations of Fused Deposition Modeling for Perovskite Active Solar Cells

The advent of Fused Deposition Modeling (FDM; or 3D printing) has significantly changed the way many products are designed and built. It has even opened opportunities to fabricate new products on-site and on-demand. In addition, parallel efforts that introduce new materials into the FDM process have seen great advances as well. New additives have been demonstrably utilized to achieve thermal, electrical, and structural property improvements. This combination of fabrication flexibility and material additives make FDM an ideal candidate for investigation of perovskite materials in new solar cell efforts. In this work, we fabricate and characterize a perovskite-based solar cell polymer designed for the FDM fabrication processes. Perovskite solar cells have garnered major research interest since their discovery in 2009. Perovskites, specifically methylammonium lead iodide, offer beneficial properties to solar cell fabrication such as long minority charge carrier distance, high light absorption, and simple fabrication methods. Despite the great potential of these materials, however, stability remains an issue in solar cell utilization as the material degrades under ultraviolet light, exposure to oxygen and water, as well as increased temperatures. To mitigate degradation, different fabrication methods have been utilized. Additionally, multiple groups have utilized encapsulation methods post-fabrication and in situ solution processed integration of polymer materials into the solar cell to prevent degradation. In this paper, we leverage the unique ability of FDM to encapsulate perovskite materials and yield a MAPbI₃-PCL solar material as the active layer for solar cell use. In this manner, increased ability to resist UV light degradation and material stability from other environmental factors can be achieved. This study provides characterization of the material via multiple techniques like SEM (Scanning Electron Microscopy) and XRD (X-ray Diffraction) as well as absorbance, transmittance, and photocurrent response. Investigations of processing on perovskite degradation as well as initial solar simulated response are recorded. Unique aspects of the resulting material and process are noted including improved performance with increased operating temperature. Increased electron–hole pair generation is observed for 200 μm FDM-printed PCL film, achieving a 45% reduction in resistance under peak incident flux of 590 W/m2 with the addition of MAPbl₃. This work establishes insight into the use of FDM for full solar cell fabrication and points to the next steps of research and development in this growing field.

Encapsulation of perovskite quantum dots into LnIII-incorporated polymer matrix to achieve white light emission

All-inorganic perovskite quantum dots (PQDs) with high quantum efficiency and broad spectral tunability showing potential applications in light-emitting diodes (LEDs) are promising luminescent materials. However, poor stability has also become...

Highly Water-Stable Polymer-Perovskite Nanocomposites

The excellent performance of hybrid metal-halide perovskite nanocrystals (NCs) contrasts with their unsatisfactory stability in a high-humidity environment or water. Herein, polymer composite lead-halide perovskites (LHPs) NCs were prepared by casting or spin-coating to produce a high fluorescence yield and a fully water-resistant material. Poly(l-lactide) (PLla), polypropylene glycol (PPGly), and polysulfone (PSU) commercial polymers were used to prepare suspensions of MAPbBr₃-HDA NCs (MA: CH₃NH₃; HDA: hexadecylamine). The MAPbBr₃-HDA@PLla suspension exhibited a maximum fluorescence quantum yield of 93% compared to 43% for the pristine MAPbBr₃-HDA NCs. Strong emissions around 528 nm were also observed, with the same full width at half maximum value of 20 nm, demonstrating the successful fabrication of brightly luminescent LHP NCs@polymer combinations. Time-resolved photoluminescence measurements directly observed the enhanced spontaneous emission of the NCs induced by the polymeric environment. However, the cast films of MAPbBr₃-HDA NCs mixed with PLla or PPGly did not resist water immersion. On the contrary, MAPbBr₃-HDA@PPGly/PSU films containing well-dispersed ∼10 nm LHP NCs retained a bright green fluorescence emission even after 18 months under air conditions or water immersion up to 45 °C. From water contact angle measurements, profilometry, and X-ray photoelectron spectroscopy data, it could be assumed that the slightly hydrophobic PSU polymer is responsible for the high water stability of the fluorescent films, which avoids MAPbBr₃-HDA NC degradation. This work shows that the LHP NC dispersion in dissolved commodity polymers holds great promise toward the long-term stability of LHP NC composites for the future development of wearable electronic devices and other waterproof applications.

Water-assisted preparation of ethanol-dispersed CsPbBr3 perovskite nanocrystals and emissive gel

Cesium lead halide perovskite nanocrystals (PNCs) are highly attractive for optoelectronic applications due to their tunable bandgap, large absorption cross section and efficient photoluminescence. However, the dynamic ligand binding and ionic lattice make PNCs extremely sensitive to polar solvents, which greatly hinders the applications of PNCs. In this work, we first synthesize ethanol-dispersed PNCs with the assistance of water using glycyrrhizic acid (GA) as the sole capping ligand. The prepared PNCs with a mean size of 14.5 nm exhibit a narrow and symmetric emission band (full width at half maximum: 18 nm) and photoluminescence (PL) quantum yield (QY) of ~38.1%. Different with the common sense, the addition of water promotes the formation of GA-passivated PNCs due to the accelerated reaction rate of precursors and the H⁺ dissociation of GA at presence of Lewis base water. Furthermore, the ethanol-dispersed PNCs can be further transformed into emissive ethanol gels with improved stability. Our findings provide a novel strategy to achieve stable colloidal PNCs in polar solvents.

Luminescent and Robust Perovskite-Silicone Elastomers Prepared by Light Induced Thiol-Ene Reaction

The preparation of a series of luminescent perovskite-silicone elastomer (PSE) composites by embedding inorganic lead halide perovskite nanocrystals (CsPbBr₃ NCs) into networks constructed by trimethylolpropane tris(2-mercaptoacetate) and sulfone-containing silicone copolymers with vinyl side groups (PSMVS) is reported herein. The networks are obtained by an environmentally friendly thiol-ene cross-linking reaction under 30 W household LED light. The conducted analysis shows that the prepared PSEs display strong green fluorescence due to encapsulation of CsPbBr₃ NCs, which constitute a luminescent center in sulfone-containing silicone networks. Using PSMVS as basic polymers instead of commercial polysiloxanes endows PSEs with enhanced mechanical strength and excellent luminescent stability at high temperatures. The PSEs show robust tensile stress and >650% elongation. Additionally, the construction of colorful ultraviolet light-emitting diodes (UV-LEDs) by an in situ cross-linking process is described.

Aromatic nonpolar organogels for efficient and stable perovskite green emitters

Existing gels are mostly polar, whose nature limits their role in soft devices. The intermolecular interactions of nonpolar polymer-liquid system are typically weak, which makes the gel brittle. Here we report highly soft and transparent nonpolar organogels. Even though their elements are only carbon and hydrogen, their elastic modulus, transparency, and stretchability are comparable to common soft hydrogels. A key strategy is introducing aromatic interaction into the polymer-solvent system, resulting in a high swelling ratio that enables efficient plasticization of the polymer networks. As a proof of applicability, soft perovskite nanocomposites are synthesized, where the nonpolar environment of organogels enables stable formation and preservation of highly concentrated perovskite nanocrystals, showing high photoluminescence efficiency (~99.8%) after water-exposure and environmental stabilities against air, water, acid, base, heat, light, and mechanical deformation. Their superb properties enable the demonstration of soft electroluminescent devices that stably emit bright and pure green light under diverse deformations.

Ionic complexation of endblock-sulfonated thermoplastic elastomers and their physical gels for improved thermomechanical performance

Thermoplastic elastomers (TPEs) composed of nonpolar triblock copolymers constitute a broadly important class of (re)processable network-forming macromolecules employed in ubiquitous commercial applications. Physical gelation of these materials in the presence of a low-volatility oil that is midblock-selective yields tunably soft TPE gels (TPEGs) that are suitable for emergent technologies ranging from electroactive, phase-change and shape-memory responsive media to patternable soft substrates for flexible electronics and microfluidics. Many of the high-volume TPEs used for these purposes possess styrenic endblocks that are inherently limited by a relatively low glass transition temperature. To mitigate this shortcoming, we sulfonate and subsequently complex (and physically crosslink) the endblocks with trivalent Al³⁺ ions. Doing so reduces the effective hydrophilicity of the sulfonated endblocks, as evidenced by water uptake measurements, while concurrently enhancing the thermomechanical stability of the corresponding TPEGs. Chemical modification results, as well as morphological and property development, are investigated as functions of the degree of sulfonation, complexation and TPEG composition.

Photoluminescence spectral broadening, chirality transfer and amplification of chiral perovskite materials (R-X-p-mBZA)2PbBr4 (X = H, F, Cl, Br) regulated by van der Waals and halogen atoms interactions

We introduced halogen-substituted chiral molecules as A-site cations to synthesize a series of novel organic–inorganic hybrid 2D chiral perovskite materials (R-X-p-mBZA)₂PbBr₄ (X = H, F, Cl, Br; p: para-position; mBZA = α-methylbenzylamine).

Fabrication of silver chalcogenolate cluster hybrid membranes with enhanced structural stability and luminescence efficiency

The present study reports the fabrication of a silver chalcogenolate cluster hybrid membrane (SCC membrane) through self-assembly of SCCs, and then covalent cross-linking of the modified SCC assembled materials. This strategy provides access to silver clusters with superior chemical stability and enhanced luminescence efficiency for practical applications.