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Cell migration determines the complete development of mammalian tissue and other pathological phenomena. To investigate the effect of chemical stimuli on such behavior, cells are triggered to translate by the concentration gradient of different molecules on 2D substrates in vitro. But to date unfortunately the polymeric scaffolds for cell migration in 3D environment with chemical stimuli have not been proposed and developed yet. Herein, a novel 3D composite scaffold with an internal chemical boundary is fabricated by electrospinning and mask-assisted electrospray so that the deposition of PBG-N3 particles is confined at specific area initially. The chemical boundary is subsequently formed after selective surface modification of the particles via click reaction. Using a fluorescent alkyne, the boundary of modified regions is clearly observed by fluorescence microscope. This innovative bio-material has the potential to serve as a promising scaffold for investigating the effect of chemical stimuli on cell migration and growth in 3D environment and further on to the application in tissue engineering.

Correction for ‘Exploration of biomimetic poly(γ-benzyl-l-glutamate) fibrous scaffolds for corneal nerve regeneration’ by Tien-Li Ma et al., J. Mater. Chem. B, 2022, 10, 6372–6379, https://doi.org/10.1039/D2TB01250B.

Perovskite solar cell is a thin-film cell made from solution process including coating, sintering, crystallization, and then encapsulated to become a solar cell that can generate electricity at low cost. At present, the power conversion efficiency of laboratory-produced small cell (

Time-of-flight secondary-ion mass spectrometry (ToF-SIMS) has been used for gaining insights into perovskite solar cells (PSCs). However, the importance of selecting ion beam parameters to eliminate artifacts in the resulting depth profile is often overlooked. In this work, significant artifacts were identified with commonly applied sputter sources, i.e., an O

A variety of cellulose-based polymer composite materials has been developed and show different impacts on the morphologies and properties of composites. Herein, we report the morphologies and properties of composites by blending polyurethane (PU) with either ethyl cellulose (EC) or cellulose nanofiber (CNF) through either drop-casting or electrospinning process. EC is homogenously mixed with PU without microphase separation and enhanced Young's modulus of composites from 0.04 to 6.94 MPa. The CNF is heterogeneously distributed in PU/CNF composites without interference on the PU microstructure and slightly increased modulus to 0.24 MPa. While the shearing force of the electrospinning process slightly affects the PU/EC composites, it drastically enhances PU crystallinity and Young's modulus to 54.95 MPa in PU/CNF composites. A model is established to summarize the effect of cellulose additives, compositions, and processes on PU/cellulose composites, providing a comprehensive understanding for designing future cellulose composites.

Detecting and discriminating chemical vapors are essential for environmental monitoring and medical diagnostics. In this study, highly sensitive chemical vapor sensors fabricated from fluorinated t...

Anionic and cationic defects are considered as one of the crucial factors that affect carrier transport property and degradation of perovskite photovoltaic materials. Herein, we demonstrate a simpl...

Using a novel ultraviolet (UV) irradiation method, we processed a high-performance thin-film transistor (TFT) at low temperatures. Satisfactory device integrity that was demonstrated by high field-effect mobility values of 92 and 43 cm2/Vs, small subthreshold slopes of 74 and 81 mV/decade, and ON-current/ OFF-current values of $3\times 10^{6}$ and $7\times 10^{5}$ was achieved for the SnO2 TFT at low processing temperatures of 180 °C and 100 °C, respectively. The results of X-ray photoelectron spectroscopy showed that the UV irradiation considerably increased the presence of Sn4+ and reduced the presence of unwanted Sn2+, even at low processing temperatures, improving the quality of SnO2.

Oligo(ethylene glycol) (OEG) side chains are widely used in donor-acceptor conjugated polymers (D-A CPs) and enable the polymers to dissolve and be processed in environmentally friendly and cost-effective nonchlorinated solvents, such as water. However, the OEG effect on the physical properties of D-A CPs has not been thoroughly studied and sometimes the results are controversial. In this study, two oligothiophene-isoindigo based conjugated polymers, P3TI and P4TI, are selected as model polymers to investigate the OEG effect. PnTI has octyl side chains on the oligothiophene unit and 2-hexyldecyl side chains on the isoindigo unit. The replacement of an alkyl side chain with OEG not only changes the optical and thermal properties but also the molecular arrangements of the polymers such as π-π d-spacing, crystallinity, and packing orientation. The domination of the crystallization behavior changes from the oligothiophene unit to the isoindigo unit when the bulky alkyl group is replaced by the flexible and linear OEG. The packing changes from edge-on to face-on orientation. The results are intriguing and provide new insights into this class of polymers.

Nanostructures in conducting polymer films can enhance charge carrier and ion transfer, provide porosity with high specific area and confer unique optoelectronic properties for potential applications. A general and facile synthesis has been developed to prepare nanostructured conducting polymer films without the need for using templates. This simple approach employs hyperbranched polymers as additives to tune the morphology of conducting polymer films into a continuous nanofibril network. Nanostructured conducting polymer films with improved crystallinity exhibit good charge carrier transport and stable nanofibril network, without sacrificing either property upon removing residual additives. Polymer field-effect transistor sensors have been used to demonstrate the benefits of the large surface area provided by the nanofibril network. The sensors with porous nanostructures exhibit lower detection limits (two times lower) and faster response times (33% faster) compared to the sensors without nanostructures. This general approach can advance the knowledge and development of nanostructured conducting polymer films for energy harvesting and storage, electronics, catalysts, sensors and biomedical applications.

Three D–A π-conjugated copolymers PnTIF (where n = 2, 4, or 6), composed of isoindigo electron acceptor units and difluorinated bithiophene (BTF) electron donor units, were synthesized and characterized. The HOMO and LUMO energy levels, solubility (and miscibility with PCBM), crystallinity (and crystalline orientation) and PnTIF:PCBM thin film morphology (nano-fibrillar network and phase separation) of the copolymers could be adjusted by the number (0 for P2TIF, 1 for P4TIF, 2 for P6TIF) of flexible 3-dodecylthiophene spacers between the isoindigo and BTF units. From the tested polymer solar cells fabricated with PnTIF:PCBM bulk heterojunctions, P4TIF:PC61BM solar cells exhibited a remarkably high short-circuit current density of ∼22 mA cm−2 together with a fill factor of ∼61% and an open-circuit voltage >0.80 volt, resulting in a power conversion efficiency of 10.7%, making it one of the highest among PC61BM-based polymer solar cells.

Neural tissue engineering has emerged as a promising technology to cure neural damages. Although various synthetic polymers with good biocompatibility and biodegradability have been adopted as candidate materials for scaffolds, most of them require the incorporation of biomolecules or conductive materials to promote the growth of long axons. Herein we demonstrate for the first time a unique peptide-based polyelectrolyte that is ionically conductive and contains a neurotransmitter, glutamic acid. The designed polymer, sodium salt of poly(γ-benzyl-l-glutamate)

Toxic lead and poor stability are the main obstacles of perovskite solar cells. Lead-free silver bismuth iodide (SBI) was first attempted as solar cells photovoltaic materials in 2016. However, the short-circuit current of the SBI rudorffite materials is commonly Na/Cs-SBI reduced the electron–holes pairs recombination and promoted the carrier transport of rudorffite solar cells. Finally, the Na/Cs-SBI rudorffite solar cell not only exhibited a power conversion efficiency (PCE) of 2.50%, a 46% increase to the SBI device (PCE = 1.71%), but also was stable in ambient conditions for >6 months.

The composite electron transporting layer (ETL) of metal oxide with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) prevents perovskite from metal electrode erosion and increases p-i-n perovskite...

Low-cost and solution-processed perovskite solar cells have shown great potential for scaling-up mass production. In comparison with the spin coating process for fabricating devices with small areas, the blade coating process is a facile technique for preparing uniform films with large areas. High-efficiency perovskite solar cells have been reported using blade coating, but they were fabricated using the toxic solvent N,N-dimethylformide (DMF) in nitrogen. In this work, we present highly efficient blade-coated perovskite solar cells prepared using a green solvent mixture of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) in an ambient environment. By carefully controlling the interface, morphology, and crystallinity of perovskite films through composition variations and additives, a high power conversion efficiency of 17.02% is achieved in air with 42.4% reduction of standard deviation in performance. The findings in this work resolve the issues of scalability and solvent toxicity; thus, the mass production of perovskite solar cells becomes feasible.

Perovskite solar cells (PSCs) have become one of the most promising renewable energy converting devices. However, in order to reach a sufficiently high power conversion efficiency (PCE), the PSCs typically require a high-temperature sintering process to prepare mesostructured TiO

The donor–acceptor conjugated polymers (CPs) of terthiophene–thieno[3,4-c]pyrrole-4,6-dione (3T-TPD) are widely used to fabricate low-cost flexible electronics. We present a comprehensive study of the side chain effect on the optical properties, electrochemical properties, thermal properties, and self-assembly behavior of 3T-TPD CPs, including side chain location (outward vs inward), type (tetraethylene glycol (TEG) vs dodecyl), and length (octyl vs hexyl vs butyl). For the side chain location effect, the polymers with outward side chains show better coplanarity of backbone than the polymers with inward side chains, leading to form lamellae structure. However, interestingly, the inward series polymers exhibit novel hexagonal structure. Through replacing dodecyl chains with TEG chains and changing the side chain length, ultrahigh ordered lamellae and hexagonal structure can be obtained. Furthermore, two models are purposed to explain the formation mechanism of lamellae and hexagonal structure. This study c...

Rod-coil block copolymers (BCPs) can self-assemble into nanostructures that are useful for the fabrication of nanodevices. However, BCPs are generally difficult to self-assemble into highly ordered nanostructures due to their low chain mobility and strong rod-rod interaction. A facile approach is developed to achieve rapid self-assembly of rod-coil BCPs by blending them with selective additive and annealing in vacuum. Poly(diethyl hexyl oxy-p-phenylene vinylene)-b-poly(methyl methacrylate) (DEHPPV-b-PMMA or PVM) was used as a model copolymer to validate this approach. By adding 30 wt% of a rod-selective additive, p-phenylene vinylene (PV), into the PVM containing 67% (v/v) PMMA, the copolymer can easily self-assemble into lamellae structure at 150 °C for 1.5hr under 0.05 torr. This is a significant improvement over the 200 °C for 60 h for the sample without additive and vacuum annealing. This energy conservation process should have broad application in the fabrication of highly ordered nanostructure using BCPs.

Lead halide perovskite-structured solar cells (PSCs) have drawn great attention due to a rapid improvement in their photoelectric conversion efficiency in recent years. In this study, we have enhanced photovoltaic performance by using mesoscopic zinc-doped TiO2 (meso-Zn:TiO2) as the electron extraction layer. Zn:TiO2 nanoparticles (Zn:TiO2 NPs) with various zinc doping levels were synthesized by combining sol–gel and hydrothermal methods. The synthesized Zn:TiO2 NPs were used to fabricate electron extraction layers by a screen-printing method. We systematically investigated the surface morphology, crystal structure, contact angle, charge carrier dynamics, electron mobility, and electrical conductivity of various meso-Zn:TiO2. Furthermore, photo-assisted Kelvin probe force microscopy (KPFM) was used to analyze the surface potential of perovskite films coated with various meso-Zn:TiO2 to understand the electron extraction behavior under the illumination of light at various wavelengths. Moreover, the energy levels of various meso-Zn:TiO2 were estimated by ultraviolet photoelectron spectroscopy (UPS) and UV-vis absorption spectroscopy. We discovered that the 5.0 mol% meso-Zn:TiO2 exhibited the optimal band alignment with perovskite. Finally, the average power conversion efficiency (PCE) of PSCs with meso-Zn:TiO2 was enhanced from 13.1 to 16.8%, and such fabricated PSC yielded a champion PCE of 18.3%.

Metal oxide thin films made from a sol–gel solution process are promising candidates for stable, low cost, and high performance electronic devices. Reducing the thermal budget required for their crystallization process can relax the fabrication limitation and expand their possible applications. We show that with the addition of an adequate amount of tetramethylammonium hydroxide (TMAOH) in the precursor solution, the activation energy of the sol–gel reaction can be reduced by about 50%. Using this strategy, not only can the required thermal treatment time and temperature of the sol–gel reaction be significantly reduced but also the quality of the film can be improved. The enhanced reaction rate can be ascribed to the presence of hydroxyl anions, which facilitate the formation of the metal hydroxide and the subsequent metal oxide. Additionally, the strategy developed here can be applied to multiple kinds of metal oxides. By this method, the processing temperature can be lowered by at least 50 °C and the time can be shortened by half for the fabrication of electronic devices such as thin film transistors and photovoltaics. Our results open up a new paradigm to fabricate highly crystalline metal oxide thin films quickly at an energy saving low temperature using the solution process.

Sol–gel metal oxide films are an important type of functional materials for energy technologies and beyond owing to their versatile properties and ease of processing, but their applications are limited by the typically required high sintering temperatures. This study reports a novel phenomenon where the sintering temperatures of sol–gel metal oxide films were substantially lowered when a metal phase was embedded within the sol–gel precursor films. Morphological and compositional analyses revealed that the reduction in sintering temperatures was enabled by a mechanism similar to the metal-induced crystallization (MIC) process, with a distinction that catalysis of sol–gel reactions occurred alongside the induction of crystallization. We observed this catalytic MIC (c-MIC) mechanism in a variety of sol–gel material systems including NixO with embedded Au or Ag; TiOx with embedded Ni, Au, or Pt; and SnOx with embedded Ni. Based upon this concept, we demonstrated highly efficient flexible and rigid organic/inorganic hybrid perovskite solar cells (PSCs) using a low-temperature-sintered NixO film embedded with Au nanoislands as the hole-transporting layer (HTL). The c-MIC mechanism reduced the sintering temperature of the Au-embedded NixO HTL by 100 °C, making the NixO process compatible with plastic substrates while allowing the NixO HTL to retain more NiOOH surface groups, which enhanced hole collection and improved the quality of the perovskite layer. Thanks to the advantages of the c-MIC NixO film, the flexible and rigid PSCs achieved high power conversion efficiencies of up to 15.9 and 19.0%, respectively, which were sustained for >1200 h at 65 °C and 65% relative humidity. Our findings provide a practical route for low-temperature fabrication of high-quality oxide functional films by solution-based sol–gel processes, which will be valuable to a wide variety of applications in addition to thin film solar cells.

Bulk heterojunction (BHJ) perovskite solar cells have recently attracted increased interest because of a significantly enhanced interface between perovskite and the n-type material in the active layer for efficient charge separation and increased power conversion efficiency (PCE). [6,6]-Phenyl-C61-butyric acid methyl ester (PC61BM) is the most commonly used n-type material in BHJ perovskite solar cells owing to its high electron mobility. However, it is very difficult to fabricate BHJ perovskite films because of the poor solubility of PC61BM in the commonly used solvent dimethylformamide (DMF). In this study, we introduced two kinds of fluorinated PC61BM (3F-PC61BM and 5F-PC61BM) as n-type materials in a BHJ perovskite film, which have higher solubility in DMF than that of PC61BM. Thus, a BHJ perovskite film can be easily fabricated in one step using a single solvent in a BHJ precursor solution system for planar perovskite solar cells. A BHJ device with a high PCE of 16.17% can be obtained by adding 0.1 wt% of 3F-PC61BM in a perovskite precursor solution to fabricate a solar cell, which outperforms the PCE of 14.12% of the pristine device. However, the addition of 5F-PC61BM decreased the PCE to lower than that of the pristine device regardless of its amount. We systematically studied the effects of the amount and type of fluorinated PC61BM on the morphology of BHJ perovskite films using SEM, AFM, GISAXS and GIWAXS. The results reveal that 3F-PC61BM can fill the pinholes between perovskite grains and passivate the defects in the pristine film. Thus, the current density (Jsc) is greatly increased. On the other hand, the self-aggregation of 5F-PC61BM in BHJ perovskite films caused the films to be full of large voids, which led to poor device performance. The dense and flat surface morphology of BHJ perovskite films containing 3F-PC61BM can also prevent the permeation of moisture into grain boundaries and enhance the device stability. Therefore, the device could maintain 80% of its original efficiency over 550 hours without any encapsulation in comparison with 240 hours for the pristine device. Our results provide a novel strategy for fabricating high-PCE and high-stability BHJ perovskite solar cells for the production of low-cost solar cells in the near future.

Perovskite solar cell is a novel photovoltaic technology with the superior progress in efficiency and the simple solution processes. Develop lead-free or lead-reduced perovskite materials is a significant concern for high-performance perovskite solar cell. Among the alkaline earth metals, the Sr2+ and Ba2+ are suitable for Pb2+ replacement in perovskite film due to fitting Goldschmidt's tolerance factor. In this study, we adopted Ba-doped and Sr-doped perovskite structured materials with different doping levels, including 1.0, 5.0, and 10.0 mol%, to prepare perovskite solar cells. Both Ba-doped and Sr-doped perovskite structured materials have a related tendency in absorption behavior and surface morphology. At 10.0 mol% doping level, the power conversion efficiency (PCE) of Sr-doped perovskite solar cells is only ∼0.5%, but the PCE of Ba-doped perovskite solar cells can be achieved to ∼9.7%. Ba-doped perovskite solar cells showed the acceptable photovoltaic characteristics than Sr-doped perovskite solar cells. Ba dopant can partially replace the amount of lead in the perovskite solar cells, and it could be a potential candidate in the field of lead-free or lead-reduced perovskite energy materials.

Hybrid lead halide perovskite structured materials have created enormous expectations for low-cost and high-performance optoelectronic devices. The light-harvesting active layer of perovskite solar cell consists of hybrid organic-inorganic lead halide-based material. In this study, we successfully fabricated the perovskite photovoltaics with partial substitution of the lead cation (Pb 2+ ) with calcium ion (Ca 2+ ). The incorporation of Ca 2+ into the original structure was analyzed to observe the doping effect on the crystalline structure and the optical properties. Moreover, UV–vis spectra showed the decreased bandgap with ascending the dopants Ca 2+ amount. 1.0 mol% Ca-doped perovskite film has the lower emission energy, and it shows the low recombination behavior. After optimizing the perovskite solar cells, the V oc is increased from 0.93 to 0.98 V, the J sc is increased from 17.4 to 19.1 mA/cm 2 and the power conversion efficiency is enhanced from 10.7 to 12.9% by using 1.0 mol% Ca-doped perovskite material.

Inorganic–organic hybrid perovskite single crystals are potential materials for the application of high performance optoelectronic devices. The exposed surface of single crystals can dramatically affect the measured properties. Facet-dependent behaviors are also speculated. However, impeded by the lack of facile facet engineering strategy for inorganic–organic hybrid perovskites, the relationship between different facets and respective performance remains elusive. In this work, we present a simple approach of ligand-mediated crystal growth to control the shape and the exposed facets of methylammonium lead iodide single crystals. The addition of oleylamine ligand can trigger the continuous morphological transition from dodecahedral-shaped single crystal enclosed by (100)T and (112)T to cubic-shaped single crystal enclosed by (110)T and (002)T while maintaining the material composition and crystalline phase. We fabricated single crystal based photodetectors and carried out the first unambiguous study on the...

Highly crystalline NiOX usually requires high annealing temperature (>300 °C) which is incompatible with flexible substrate and might consume high amount of energy. Herein, we demonstrate a facile emulsion process to synthesize highly crystalline, low temperature deposition (

A carrier transport layer and its interfacial effects on an organometal halide perovskite light harvesting layer play an influential factor in either photovoltaic performance or long-term stability of a perovskite solar cell (OHPSC). Although the understandings of the carrier transport layers and interfacial effects on regular structured OHPSCs have been explored, knowledge of an interface between hole transport layer of NiOx and perovskite in an inverted OHPSC is still necessary to be developed. Here, we performed a universal NiOx film with the sequential passivation strategy of NiCl2 (SPS-NiCl2 treatment) for either wide bandgap or narrow bandgap of OHPSCs. The SPS-NiCl2 treated NiOx film not only implements the passivation at the perovskite layer/NiOx film interface but also confers itself a gradient energy level of valance band inducing by chloride. Comprehensive characterizations reveal that the SPS-NiCl2 treated NiOx film suppresses non-radiative recombination at the interface and enlarges the splitting of the quasi-Fermi level at the interfaces. The photoconversion efficiency (PCE) of the champion device comprised of the SPS-NiCl2 treated NiOx film can achieve 19.53% with a record Voc of 1.16 V, the lowest Voc deficit of 390 mV in NiOx based inverted OHPSCs. The corresponding devices with encapsulation also exhibit superior long-term stability, and over 80% of initial PCE can be maintained after 1500 h damp-heat test. This study sheds the light on managing the interfacial issues of an inverted OHPSC and offers a feasible path to develop a universal hole transport layer for perovskite layers with different energy bandgap.

Volatile organic compounds (VOCs) sensors are the imperative technology of modern life for environmental monitoring to detect any harmful elements and to prevent lethal exposure. The sensing material is a fibrous film consisting of poly(3-hexylthiophene)(P3HT)/poly(methyl methacrylate)(PMMA) blend, and it is fabricated on a glass substrate. The P3HT/PMMA fibrous film is made by electrospinning process and shows high specific surface for solvent vapor harvesting. The P3HT/PMMA fibrous films are thus easily designed according to the extinction changes of VOCs. The P3HT/PMMA fibrous film exhibits the detection capability for VOCs. It satisfies the detection limit of acetone, toluene and o-xylene at 500 ppm. The cost of the P3HT/PMMA fibrous film is acceptable to the market in contrast to the commercial sensors toward VOCs.

Organic–inorganic lead halide perovskite solar cells are considered as one of the most promising technologies for future photovoltaics because they show high power conversion efficiency (PCE) and can be fabricated through a simple solution process. Non-toxic alkaline-earth metal cations are suitable candidates to replace toxic lead in perovskite because they maintain the charge balance in perovskite and some of them meet the tolerance factor of Goldschmidt's rule. We investigated four kinds of alkaline-earth metal cations (Mg2+, Ca2+, Sr2+, and Ba2+) to replace lead cations partially. Among these four alkaline-earth metals, the Ba2+ is most suitable for Pb2+ replacement in perovskite films and exhibits the best power conversion efficiency. Furthermore, we systematically studied the crystal structure, absorption behavior and surface morphology of Ba2+-doped perovskite films with different doping levels. The relationship between the charge carrier dynamics and Ba2+ concentration was evaluated by the time-resolved photoluminescence (TRPL) technique. The Ba2+-doped perovskite films that can be processed in the environment containing moisture (1.0% relative humidity) are stable. At the optimal 3.0 mol% Ba2+ replacement, the PCE of the fabricated solar cell is increased from 11.8 to 14.0%, and the PCE of champion devices is as high as 14.9% with increased storage stability.