Highly efficient ternary organic solar cells with excellent open-circuit voltage and fill factor via precisely tuning molecular stacking and morphology

The micro-morphology and molecular stacking play a key role in determining the charge transport process and nonradiative energy loss, thus impacting the performances of organic solar cells(OSCs). To address this issue, a non-fullerene acceptor PhC6-IC-F with alkylbenzene side-chain, possessing optimized molecular stacking, complementary absorption spectra and forming a cascade energy level alignment in the PM6:BTP-eC9 blend, is introduced as guest acceptor to improve efficiency of ternary OSCs. The bulky phenyl in the side-chain can regulate crystallinity and optimizing phase separation between receptors in ternary blend films, resulting in the optimal phase separations in the ternary films. As a result, high efficiencies of 18.33% as photovoltaic layer are obtained for PhC6-IC-F-based ternary devices with excellent fill factor(FF) of 78.92%. Impressively, the ternary system produces a significantly improved open circuit voltage(V_(oc)) of 0.857 V compared with the binary device,contributing to the reduced density of trap states and suppressed non-radiative recombination result in lower energy loss. This work demonstrates an effective approach for adjusting the aggregation, molecular packing and fine phase separation morphology to increase V_(oc) and FF, paving the way toward high-efficiency OSCs.

Metalloprotein-inspired supramolecular photodynamic nanodrugs by multicomponent coordination for deep penetration and enhanced biofilm eradication

Bacterial infections exacerbate the formation of bacterial biofilms,leading to resistance to traditional drugs,persistent infection,and even threatening patient’s life.Efficient antimicrobial materials against drug-resistant bacterial biofilms are highly desired.In this study,a photodynamic nanodrug with bacterial targeting was constructed by cooperative coordination of zinc ion with an antimicrobial peptide with hydrophobic tripeptides on the side chains and the photosensitizer chlorin e6.The supramolecular nanodrug with a uniform spherical structure possessed high photosensitizer loading capacity and enhanced photodynamic efficacy,which could deep penetrate and eradicate methicillin-resistant Staphylococcus aureus(MRSA)biofilms upon 655 nm laser irradiation.Furthermore,in vivo experiments verified the efficient elimination of MRSA biofilms on implanted catheters.This study provides a novel strategy to fabricate metalloprotein-inspired supramolecular photodynamic nanodrugs against drugresistant bacterial biofilms-associated infections in vivo.

Temperature/pH dual-responsive reversible morphology evolution of block copolymer microparticles under three-dimensional confinement

Development of block copolymer(BCP)microparticles with switchable morphology in response to external stimuli is important for exploiting new intelligent materials.In this work,thermo/p H dual-responsive nanoparticles(NPs)were employed as a cosurfactant to modulate the self-assembly morphology of polystyrene-b-poly(2-vinylpyridine)(PS-b-P2VP)microparticles within confined emulsion droplets.The co-surfactant was synthesized by grafting poly(acrylic acid)-b-poly(N-isopropylacrylamide)onto the surface of Fe3O4NP.The introduction of the dual-responsive co-surfactant enabled thermo/p H dual-responsive reversible morphology transition of the PS-b-P2VP microparticles by tailoring the hydrophobicity and interfacial affinity of the cosurfactant.By using this strategy,the thermo-inert PS-b-P2VP self-assembled into pupa-like microparticles at T=10℃ and p H7.5,which could transform into tulip-like microparticles when T was increased to 50℃.When the p H value was increased to 11,the pupa-like particles turned into onion-like microparticles although the PS-b-P2VP was inert to alkali.However,the pupa-like microparticles remained unchanged when both T and p H were simultaneously increased.The PAA-b-PNIPAM-grafted Fe3O4NP surfactants showed obvious advantages over the linear PAA-b-PNIPAM surfactants in modulating the morphology transition,since the linear PAA-b-PNIPAM could not induce the reversible shape transition of microparticles.Our work provides an efficient strategy to achieve reversible shape transformation of BCP microparticles while the internal phase structure is preserved,which may be utilized to switch the structural color properties of BCP microparticles.

Kinetically Controlled Supramolecular Block Copolymer Self-Assembly:Multicolor Photonic Crystal Patterns from a Single Formulation

Photonic crystal(PC)patterns with tunable and changeable nonvolatile structural colors printed from a single ink are of great interest for optical products but have rarely been reported because most inks can only output one respective structural color.Herein,we propose a facile yet effective kinetically controlled self-assembly strategy to address this challenge.An ink formulation containing supramolecular block copolymers(SBCPs)is developed.SBCP patterns were printed by direct-ink-writing followed by solvent annealing to generate different structural colors by simply controlling the annealing time.The self-assembly kinetic regime suggests that different colors result from various kinetically trapped metastable states.In turn,the variation in structural color enables“visualization”of the self-assembly dynamics.Furthermore,we demonstrate that these kinetically trapped structures exhibit different responsive color-change behaviors.In addition,this kinetic control strategy can be synergistic with thermodynamic control to extend the color range.This study provides a facile yet effective solution for well-designed PC patterns with tunable,responsive,and unfading colors printed from the simplest single-nozzle printer with a single colorless ink,presenting great potential in broad applications,including information storage,encryption,and anti-fake.

Photonic Crystal-Enhanced Photodynamic Antibacterial Therapy

Photodynamic antibacterial therapy(PDAT)is a kind of rejuvenating strategy that combats bacterial infection due to its admirable characteristics of noninvasiveness and broad-spectrum antibacterial capability.However,the efficiency of PDAT can be greatly hindered by limited light irradiation.Herein,we propose an enhanced PDAT by employing photonic composite films(PCFs)via slow photon and multiple scattering effects.The PCFs are obtained by UV light-initiated polymerization of poly(ethylene glycol)phenyl ether acrylate with a self-assembled SiO_(2)colloidal particle array,followed by the deposition of photosensitizers(PSs).The PCFs can prompt the PSs with matched absorption,which are deposited on their surface,to sufficiently utilize the incident light and generate more reactive oxygen species based on the slow photon phenomenon of photonic crystals and multiple scattering effects of the SiO_(2)colloidal particles.This finding demonstrates the great potential and significance of PCFs in the field of PDAT,which may reduce the requirements of excitation equipment and avoid damage to normal tissues from exposure to huge light energy.

Bioinspired hybrid patches with self-adhesive hydrogel and piezoelectric nanogenerator for promoting skin wound healing

Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy for skin wound repair.However,there has been an urgent need for wearable and point-of-care electrical stimulation devices that have self-adhesive and mechanical properties comparable to wound tissue.Herein,we develop a bioinspired hybrid patch with self-adhesive and piezoelectric nanogenerator(HPSP)for promoting skin wound healing,which is composed of a mussel-inspired hydrogel matrix and a piezoelectric nanogenerator based on aligned electrospun poly(vinylidene fluoride)nanofibers.The device with optimized modulus and permeability for skin wear can self-adhere to the wound site and locally produce a dynamic voltage caused by motion.We show that the HPSP not only promotes fibroblast proliferation and migration in vitro,but also effectively facilitates the collagen deposition,angiogenesis,and re-epithelialization in vivo with the increased expressions of crucial growth factors.The HPSP reduces the wound closure time of full-thickness skin defects by about 1/3,greatly accelerating the healing process.This patch can serve as wearable and real-time electrical stimulation devices,potentially useful in clinical applications of skin wound healing.

Polymersome formation by solvent annealing-induced structural reengineering under 3D soft confinement

A solvent annealing-induced structural reengineering approach is exploited to fabricate polymersomes from block copolymers that are hard to form vesicles through the traditional solution self-assembly route.More specifically,polystyrene-b-poly(4-vinyl pyridine)(PS-b-P4VP)particles with sphere-within-sphere structure(SS particles)are prepared by three-dimensional(3D)soft-confined assembly through emulsion-solvent evaporation,followed by 3D soft-confined solvent annealing upon the SS particles in aqueous dispersions for structural engineering.A water-miscible solvent(e.g.,THF)is employed for annealing,which results in dramatic transitions of the assemblies,e.g.,from SS particles to polymersomes.This approach works for PS-b-P4VP in a wide range of block ratios.Moreover,this method enables effective encapsulation/loading of cargoes such as fluorescent dyes and metal nanoparticles,which offers a new route to prepare polymersomes that could be applied for cargo release,diagnostic imaging,and nanoreactor,etc.

Microfluidics-assisted optimization of highly adhesive haemostatic hydrogel coating for arterial puncture

Although common in clinical practice,bleeding after tissue puncture may cause serious outcomes,especially in arterial puncture.Herein,gelatin-tannic acid composite hydrogels with varying compositions are prepared,and their adhesive properties are further optimized in microfluidic channel-based simulated vessels for haemostasis in arterial puncture.It is revealed that the composite hydrogels on the syringe needles used for arterial puncture should possess underwater adhesion higher than 4.9 kPa and mechanical strength higher than 86.0 kPa.The needles coated with the gelatin-tannic acid composite hydrogel completely prevent blood loss after both vein and arterial puncture in different animal models.This study holds great significance for the preparation of haemostatic needles for vessel puncture,and gelatin-tannic acid hydrogel coated needles may help to prevent complications associated with arterial puncture.

Transparent photo thermal hydrogels for wound visualization and accelerated healing

Utilizing photothermal hydrogels as a wound dressing is a promising strategy to accelerate wound healing.Usually,a photothermal hydrogel has a strong light-absorbing capability,and hence its transparency can be largely sacrificed,which is unbeneficial for the visual monitoring of wound states.It remains challenging to balance the trade-off between the photothermal conversion and wound visualization for the photothermal hydrogel dressing.Herein,a composite photothermal hydrogel film with high transparency is presented for the visual monitor of the wound,which is constructed by incorporating CsxW03 nanorods into the networks of polyacrylamide hydrogels.The composite photothermal hydrogel film exhibits high light absorption in the near-infrared region and high transmittance in the visible light region.Under 980 nm laser irradiation,the composite hydrogel can be heated up to 45°C.In vivo animal experiment on mouse skin wound model shows that the composite hydrogel film can locally heat the skin wound to accelerate healing while maintaining more than 70%transparency to realize real-time observation of the wound.This study provides the first attempt to solve the problem of opacity in photothermal hydrogel dressings,promoting the possibility of its clinical applications.

Hierarchical Microphase Behaviors of Chiral Block Copolymers under Kinetic and Thermodynamic Control

Chiral superstructures in confined spaces are subtly affected by the complex interplay among various noncovalent interactions,details of which are still in adequately understood.Herein,we report the threedimensional confined assembly of the chiral block copolymers of polystyrene-block-poly(D-lactide)andits enantiomer in emulsion droplets and demonstrate unprecedented successive microphase transformations from single helices to double helices with inverted helicity,and then to twisted cylinders in the constructedcolloidal particles.Theabovehierarchical structural transformations of chiral microphases are kinetically dependent and can further transform into thermodynamically stable achiral cylinders with saddle-shaped topology upon solvent annealing.The formation and subsequent structural transformations as well as thefinal degeneration of chiral architectures provide guidance to understand the chiral evolution at different length scales within spherical confined space and to fabricate biomimetic systems.

Chiral transfer-dictated self-assembly of chiral block copolymers

Chiral structures not only exist in nature widely,they also emerge in artificial systems,attracting myriad attentions due to their excellent mechanical,optical,electrical,and magnetic properties.Self-assembly of chiral block copolymers(BCPs*),where at least one block consists of chiral centers,represents a facile strategy to form helical/spiral/network structures with a controlled chirality.Usually,morphological chirality of BCP*assemblies was closely associated with molecular and conformational chirality of the chiral block.Generally,chiral assemblies arose from molecular chirality of BCPs*,transferring up in the assembly process and dictated the chirality at a higher hierarchical level.In contrast,notwithstanding similar assemblies could be observed from achiral BCPs under certain conditions,both left-and right-handed ones were usually observed simultaneously without a preference.Moreover,unique feature of BCPs*to access to controllable chiral assemblies affords an opportunity to prepare advanced functional materials.Herein,we dedicated a review on assembly of BCPs*into chiral assemblies in bulk/films,selective solvents,and confined spaces.The chiral transfer process in these assembly scenarios were discussed and highlighted as a key contributor to morphological chirality.Functionalities and representative applications of BCP*assemblies were also described,followed by present challenges and future prospects of BCP*self-assembly.