Ultrathin Active Layer Research Articles

Wearable and Multiplexed Biosensors based on Oxide Field-Effect Transistors.

Wearable sensors designed for continuous, non-invasive monitoring of physicochemical signals are important for portable healthcare. Oxide field-effect transistor (FET)-type biosensors provide high sensitivity and scalability. However, they face challenges in mechanical flexibility, multiplexed sensing of different modules, and the absence of integrated on-site signal processing and wireless transmission functionalities for wearable sensing. In this work, a fully integrated wearable oxide FET-based biosensor array is developed to facilitate the multiplexed and simultaneous measurement of ion concentrations (H+, Na+, K+) and temperature. The FET-sensor array is achieved by utilizing a solution-processed ultrathin (≈6nm thick) In2O3 active channel layer, exhibiting high compatibility with standard semiconductor technology, good mechanical flexibility, high uniformity, and low operational voltage of 0.005V. This work provides an effective method to enable oxide FET-based biosensors for the fusion of multiplexed physicochemical information and wearable health monitoring applications.

Highly-sensitive ultrathin flexible pressure sensor based on quasi-2D conductive network for human physiological signal monitoring

Ultrathin flexible pressure sensors are highly desirable for human physiological signal monitoring due to their portability and ability to conform to the body. However, existing ultrathin pressure sensors face challenges in balancing the sensitivity and their range. A spatial-dimensionally constrained strategy was proposed to construct an ultrathin active layer. In detail, multi-walled carbon nanotubes (MWCNTs) with an average length of ∼1.3 μm were intentionally spin-coated into a thin thermoplastic polyurethane (TPU) film with a thickness of 1.5 μm. By doing so, a quasi-2D MWCNTs conductive network is constructed, which enabled the sensor to have ultrahigh sensitivity of 27.04 kPa−1, a wide liner detection range of 0.2–24 kPa, ultrafast response time of 40 ms and a recovery time of 10 ms, and high durability in 1500 cycles under 0.2 kPa with loading/unloading frequency of 2 Hz. Thanks to this superior performance, the ultrathin pressure sensor can be used to monitor human movement and physiological signals, including finger touch, finger bending, wrist bending, and deep breathing. Moreover, the sensor can be attached to the side wall of the tip of the renal ureteroscope, allowing for the monitoring of renal pelvic pressure. Therefore, this spatial-dimensionally constrained strategy will open up a new way to fabricate highly sensitive ultrathin pressure sensors and have great application prospects in health monitoring.

Two-dimensional model of ion transport in composite membranes active layers with TEM-scanned morphology

Ion rejection by composite membranes for RO/NF is performed by an ultrathin polyamide active layer (AL) with non-uniform thickness. Current models explain the solute and water fluxes by concentration and potential in AL of uniform properties, there are studies showing the effects of its topology on permeability. We developed a two-dimensional extension of the solution-friction model, coupling ion and water transport in irregularly-shaped charged AL, with geometry extracted from TEM images. Simulations indicated that AL with pronounced roughness lead to highly non-uniform distribution of ionic fluxes and lead to NaCl permeability greater than obtained by uniform layers. The transmembrane pressure and membrane charge can shift the relative dominance of ion transport mechanisms. In weakly charged membranes diffusion dominates, even at high water fluxes. Electromigration can counteract the convective flux in highly charged membranes. The model revealed the possibility of circular ionic currents within/around the AL. The response of the 2D model to variations in flux and salinity can be identical to the response of a 1D model, providing that the 1D model uses an appropriate equivalent membrane thickness. We provided a method to convert the detailed 2D geometry into a single number that can be computed from images' active layers.

Longitudinal Through-Hole Architecture for Efficient and Thickness-Insensitive Semitransparent Organic Solar Cells.

Semi-transparent organic solar cells (ST-OSCs) have great potential for application in vehicle- or building-integrated solar energy harvesting. Ultrathin active layers and electrodes are typically utilized to guarantee high power conversion efficiency (PCE) and high average visible transmittance (AVT)simultaneously; however, such ultrathin parts are unsuitable for industrial high-throughput manufacturing. In this study, ST-OSCs are fabricated using a longitudinal through-hole architecture to achieve functional region division and to eliminate the dependence on ultrathin films. A complete circuit that vertically corresponds to the silver grid is responsible for obtaining high PCE, and the longitudinal through-holes embedded in it allow most of the light to pass through,where the overall transparency is associated with the through-hole specification rather than the thicknesses of active layer and electrode. Excellent photovoltaic performance over a wide range of transparency (9.80-60.03%), with PCEs ranging from 6.04% to 15.34% is achieved. More critically, this architecture allows printable 300-nm-thick devices to achieve a record-breaking light utilization efficiency (LUE) of 3.25%, and enables flexible ST-OSCs to exhibit better flexural endurance by dispersing the extrusion stress into the through-holes. This study paves the way for fabricating high-performance ST-OSCs and shows great promise for the commercialization of organic photovoltaics.

Hierarchical isoporous membrane filters for simultaneous reduction of pressure drop and efficient removal of nanoscale airborne contaminants

Isoporous membranes with well-defined pore architectures offer a unique design approach to achieve a multi-scale porous network. For instance, isoporous membranes with progressively smaller pore sizes can be stacked to create a hierarchical pore network in which each length scale and the gradient of the pore network are deterministic by design. In this paper, we introduce a hierarchically-arranged multilayer isoporous air filter that comprises an ultrathin (thickness <1μm) nanoporous active filtration layer and a microporous support layer. To maximize airflow and thereby reduce pressure drop across the membrane, we engineered a gap between the nanoporous and microporous membranes by designing and fabricating microscale spacer structures akin to feed spacers used in spiral wound reverse osmosis membranes. We demonstrated that such hierarchical isoporous membranes with integrated spacers (HIM-S) can retain high filtration efficiency (>95%) for ultrafine, most penetrating particle size (MPPS) while simultaneously reducing the pressure drop across the membrane (by ∼86%).

Pushing On-Chip Photosensitivity Forward Using Edge-Driven Vertical Organic Phototransistors

Developing high-performance photosensors using prototype device architectures is essential to pushing forward developing and advancing next-generation optoelectronic applications. This work reports an organic phototransistor (OPT) with an ultra-short conducting channel (tens of nanometers) and outstanding photoelectric conversion efficiency. The OPT is based on a vertical organic field-effect transistor (VOFET) architecture, which utilizes a rolled-up metallic nanomembrane (NM) as the drain electrode and a photolithographically patterned (rectangular-shaped) perforated source electrode. These features expand the concept of conventional VOFETs as the former enables the incorporation of ultra-thin active layers and allows reliable control over gate-induced modulation of channel current. Using the engineering as abovementioned strategies, we focused on obtaining an improved device performance, studying their fundamental operating principle, and further investigating their application as photosensors. The optimized devices exhibited low operating voltages (<5 V) and enhanced on/off current ratio (∼105). The VOFET photoresponse was characterized by measuring the electrical characteristics in the dark and under illumination using three different monochromatic light colors. Under blue light, our devices demonstrated impressive photosensitivity (Pmax ≈ 105) and fast photoelectric conversion (steep light-induced threshold voltage shift), demonstrating that the rolled-up NM OPT shows excellent potential as a highly sensitive photodetector with low power consumption.

Nonreciprocal transmission of electromagnetic waves with nonlinear active plasmonic metasurfaces

Nonreciprocity is important for optical information processing, full-duplex communications, and protection of sensitive laser equipment from unwanted reflections. However, it is very challenging to obtain strong nonreciprocal response in optical frequencies, especially when nanoscale configurations are considered. In this work, we solve this problem by demonstrating a compact bifacial plasmonic metasurface that acts as an ultrathin nonreciprocal transmission filter at near-infrared frequencies. The proposed nanostructure is simple to be practically implemented, since it is composed of two silver nanostripes with different dimensions placed on both sides of an ultrathin active dielectric spacing layer. The introduced gain leads to an exceptional point formation in the linear operation regime, where unidirectional perfect transmission due to loss compensation is achieved from the presented non-Hermitian parity-time symmetric nanoscale system. The demonstrated plasmonic metasurface breaks the Lorentz reciprocity law at the nanoscale when its nonlinear response is considered, mainly due to its spatially asymmetric geometry combined with enhanced nonlinearity. Strong and broadband nonreciprocity with unity transmission contrast from opposite directions is realized under relatively low-input laser intensity values. Furthermore, asymmetric nonlinear third-harmonic generation with a pronounced contrast is also illustrated by the same nonreciprocal metasurface design. The findings of this work can lead to the realization of various self-induced nonreciprocal nanophotonic configurations, such as integrated ultrafast switches, ultrathin protective coatings, and asymmetric directional imaging devices.

Surface-confined self-reconstruction to sulfate-terminated ultrathin layers on NiMo3S4 toward biomass molecule electro-oxidation

Developing high-performance anode electrocatalysts is desirable in electrocatalytic energy devices powered by sustainable electricity. Compared to water oxidation using Ni-based anodes, electro-oxidation upgrading of biomass molecule with larger size lacks dynamics driving due to increased thickness and decreased electron transfer kinetics of insulating NiOOH amorphous layer (>50 nm) from uncontrollable in-depth reconstruction. Herein, a self-confined surface reconstruction strategy is proposed to construct ∼5 nm-thick NiOOH layers on NiMo3S4 with superior activity and stability for 5-hydroxymethylfurfural oxidation reaction (HMFOR). In-situ high-valence Mo-O coordination and sulfate-terminated anion groups effectively prevent in-depth surface oxidation, leading to the ultra-thin active layers with increased electron transfer kinetics. The surface self-reconstructed NiMo3S4 (NiMo3S4-R) exhibits nearly 100% of HMF conversion, FDCA selectivity and Faradaic efficiency, much better than sulfate-modified NiOOH and pure NiOOH. Moreover, a paired electrolyzer of NiMo3S4-R||NiMo3S4 for HMFOR||HER is also assembled with an ultralow voltage of 1.414 V at 10 mA cm−2.

Photonic crystal backbone for light trapping inside an ultrathin, low absorbing layer.

A few tens of nanometre thick ultrathin materials may suffer from a very low absorption at their band edges. In this work, we investigate a photonic crystal (PC) made of a lowcost, transparent patterned silicon nitride (SiNx) layer, conformally covered with an ultrathin active layer (e.g., 20 nm TiO2) in view of its use in various applications such as photocatalysis. A fair estimation of the absorption enhancement, considering the volume of the active material, is calculated using RCWA. A remarkable enhancement (more than ten-folds) in absorptance in the near UV range and a very high transmittance over the visible range are observed. A detailed modal analysis of the structures-of-interest unravels the Light Trapping (LT) mechanisms and allows the derivation of key design guidelines. Optical measurements on a patterned sample provide a first proof-of-concept of such possible photonic backbone structures suitable for highly efficient depollution and artificial photosynthesis for solar fuels production.

GaAs thin-film solar cells photocurrent enhancement based on a new checkered grating back-reflector architecture

In this paper, a new back-reflector architecture has been investigated that can achieve a high short-circuit current density. For this, an ultra-thin film active layer of 150 nm GaAs is used, and the back-reflector structure is made of the checkered grating of Ag metal and photovoltaic material, i.e., GaAs. Hence, to decrease the initial reflection of the front surface of the cell and increase the optical path length, an anti-reflector layer is used. This checkered grating back-reflector structure by the scattering effect can reflect the unused photons into the photovoltaic layer, and these photons can travel a longer path in the photovoltaic layer, so have more chance to absorb. For proving of better performance of this structure, the simulation results are compared with a solar cell with flat BRS and the bare solar cell, that these two structures have the same volume of the photovoltaic layer as the main structure. The results of simulations show that the designed structure can achieve a short-circuit current density of 36.51 mA/cm2 and 28.04 mA/cm2, and conversion efficiency of 33.14% and 25.24%, respectively with and without the presence of anti-reflector coating.

Nanogradient Hydrophilic/Hydrophobic Organosilica Membranes Developed by Atmospheric-Pressure Plasma to Enhance Pervaporation Performance.

Organosilica membranes are a promising candidate for pervaporation dehydration owing to their tunable molecular sieving characteristics and excellent hydrothermal stability. Herein, we report a facile modification using an atmospheric-pressure water vapor plasma to enhance the pervaporation performance of organosilica membranes. The surface of methyl-terminated organosilica membranes was treated by water vapor plasma to develop an ultrathin separation active layer suitable for pervaporation dehydration. The surface hydrophilicity was increased by water vapor plasma due to oxidative decomposition of methyl groups to form silanol groups. The plasma-modified layer had a thickness of several nanometers and had a silica-like structure due to the condensation of silanol groups. The plasma-modified organosilica membranes exhibited an improved molecular sieving property owing to the formation of highly cross-linked siloxane networks with a pore size of approximately 0.4 nm. The membranes also exhibited an excellent permselectivity in the dehydration of alcohols due to the nanometer-thick separation active layer with controlled pore size and increased hydrophilicity. The plasma-modified membranes showed high H2O permeance exceeding 10-6 mol m-2 s-1 Pa-1 with permeance ratios for H2O/EtOH and H2O/IPA of 517-3050 and >10 000, respectively, in the dehydration of 90 wt % aqueous solutions at 50 °C, which is among the highest permselectivities for silica-based membranes. Furthermore, the plasma-modified membranes displayed highly efficient dehydration performance for a H2O/MeOH mixture. The H2O permeance and H2O/MeOH permeance ratio in the dehydration of a 90 wt % MeOH aqueous solution at 50 °C were (2.3-3.0) × 10-6 mol m-2 s-1 Pa-1 and 31-143, respectively, which exceeded the permeance-selectivity trade-off of conventional membranes including polymeric, silica-based, and zeolite membranes. The results indicate that the proposed plasma-assisted approach can enhance the pervaporation performance of organosilica membranes via the modification under atmospheric pressure and at room temperature.

Electron irradiation-induced defects for reliability improvement in monolayer MoS2-based conductive-point memory devices

Monolayer molybdenum disulfide has been previously discovered to exhibit non-volatile resistive switching behavior in a vertical metal-insulator-metal structure, featuring ultra-thin sub-nanometer active layer thickness. However, the reliability of these nascent 2D-based memory devices was not previously investigated for practical applications. Here, we employ an electron irradiation treatment on monolayer MoS2 film to modify the defect properties. Raman, photoluminescence, and X-ray photoelectron spectroscopy measurements have been performed to confirm the increasing amount of sulfur vacancies introduced by the e-beam irradiation process. The statistical electrical studies reveal the reliability can be improved by up to 1.5× for yield and 11× for average DC cycling endurance in the devices with a moderate radiation dose compared to unirradiated devices. Based on our previously proposed virtual conductive-point model with the metal ion substitution into sulfur vacancy, Monte Carlo simulations have been performed to illustrate the irradiation effect on device reliability, elucidating a clustering failure mechanism. This work provides an approach by electron irradiation to enhance the reliability of 2D memory devices and inspires further research in defect engineering to precisely control the switching properties for a wide range of applications from memory computing to radio-frequency switches.

Collagen fiber membrane as multi-functional support enabled rational design of ultrahigh-flux separation membrane for the remediation of oil contamination in water

Membrane separation is a promising approach for the remediation of oil contamination in water. High-flux separation of membrane relies on the rational design of ultrathin active layer to significantly reduce mass transfer distance for achieving high separation flux, while the ultrathin active layer is usually fragile with poor mechanical strength, which has to be supported on a support. Herein, we employed collagen fiber membrane (CFM) as multi-functional support for the in-situ growth of polyacrylonitrile (PAN) layer by electrospinning to prepare the high-performance PAN/CFM composite membrane. Due to the amphiphilic nature and strong capillary effect, CFM played the role as multi-functional support to provide separation effectiveness and boosted separation flux. The PAN/CFM composite membrane enabled ultrahigh separation flux (e.g., 51751.59 L m−2 h−1 bar−1) to a variety of oil-in-water emulsion, which was one order of magnitude higher than that of commercial polyethersulfone membrane and 1.86-fold to that of cellulose acetate membrane. Furthermore, the PAN/CFM composite membrane retained high separation flux (e.g., 11046.97 L m−2 h−1 bar−1) during the 5th separation cycle, providing appreciable anti-fouling capability. Therefore, our findings provided a promising way to effectively resolve the problem of oil contamination in water.

Toward Enhancing Desalination and Heavy Metal Removal of TFC Nanofiltration Membranes: A Cost-Effective Interface Temperature-Regulated Interfacial Polymerization.

Polyamide (PA) chemistry-based nanofiltration (NF) membranes have an important role in the field of seawater desalination and wastewater reclamation. Achieving an ultrathin and defect-free active layer via precisely controlled interfacial polymerization (IP) is an effective routine to improve the separation efficiencies of NF membranes. Herein, the morphologies and chemical structures of the thin-film composite (TFC) NF membranes were accurately regulated by tailoring the interfacial reaction temperature during the IP process. This strategy was achieved by controlling the temperature (-15, 5, 20, 35, and 50°) of the oil-phase solutions. The structural compositions, morphological variations, and separation features of the fabricated NF membranes were studied in detail. In addition, the formation mechanisms of the NF membranes featuring different PAs were also proposed and discussed. The temperature-assisted IP (TAIP) method greatly changed the compositions of the resultant PA membranes. A very smooth and thin PA film was obtained for the NF membranes fabricated at a low interfacial temperature; thus, a high 19.2 L m-2 h-1 bar-1 of water permeance and 97.7% of Na2SO4 rejection were observed. With regard to the NF membranes obtained at a high interfacial temperature, a lower water permeance and higher salt rejection with fewer membrane defects were achieved. Impressively, the high interfacial temperature-assisted NF membranes exhibited uniform coffee-ring-like surface morphologies. The special surface-featured NF membrane showed superior separation for selected heavy metals. Rejections of 93.9%, 97.9%, and 87.7% for Cu2+, Mn2+, and Cd2+ were observed with the optimized membrane. Three cycles of fouling tests indicated that NF membranes fabricated at low temperatures exhibited excellent antifouling behavior, whereas a high interface temperature contributed to the formation of NF membranes with high fouling tendency. This study provides an economical, facile, and universal TAIP strategy for tailoring the performances of TFC PA membranes for environmental water treatment.

Near field control for enhanced photovoltaic performance and photostability in perovskite solar cells

We present a strategy for photon management in front contact of perovskite solar cells (PSCs) compatible with tandem and flexible PSCs capable of optimizing device characteristics while providing an additional mechanism to overcome excessive focusing that affects the device’s photostability. Rigorous validation of the numerical modeling used was performed by fabricating PSCs in a superstrate configuration optimized to reach high performance, ECE = 17.4%, V OC = 1.02 V, J SC = 22.3 mA/cm 2 , and FF = 77%. These 3D electromagnetic simulations combining the finite-difference time-domain (FDTD) and finite element method (FEM) techniques provide detailed insights of the photonic and electrical effects in PSCs. Numerical optimization of the dual capabilities of a novel nanostructured front contact enables control of the absorbed power density distribution to maximize efficiency while simultaneously minimizing nanostructure-related sub-wavelength focusing effects. In-depth analysis of the proposed photon management reveals enhanced electrical characteristics to maximize charge extraction leading to J SC enhancements of ~15 that can be as high as 33% for ultra-thin active layers suitable for flexible PSCs compared to planar PSCs performance. Furthermore, we show that the design of the front contact layer’s nanostructure enables control of the power density distribution in the device to engineer PSCs' photostability without compromising performance enhancements afforded by the nanophotonic front contact. Details of the nanophotonic front contact, device, and fabrication process are provided. • The front contact integrated with hybrid nanoholes is designed for efficient perovskite solar cells (PSCs). • Demonstrates the ability to modulate the illumination for high efficiency and better photostability of PSCs. • Optoelectronic device modeling and performance, including photonic response, were investigated by 3D Multiphysics approach. • Validation of the Multiphysics approach against high-quality PSC’s detailed experimental data is conducted. • The proposed nanophotonic device allows enhancing J SC and ECE by 15~33% and 30%, respectively, compared to the reference device.

Proton‐Radiation Tolerant All‐Perovskite Multijunction Solar Cells

AbstractRadiation‐resistant but cost‐efficient, flexible, and ultralight solar sheets with high specific power (W g−1) are the “holy grail” of the new space revolution, powering private space exploration, low‐cost missions, and future habitats on Moon and Mars. Herein, this study investigates an all‐perovskite tandem photovoltaic (PV) technology that uses an ultrathin active layer (1.56 µm) but offers high power conversion efficiency, and discusses its potential for high‐specific‐power applications. This study demonstrates that all‐perovskite tandems possess a high tolerance to the harsh radiation environment in space. The tests under 68 MeV proton irradiation show negligible degradation (&lt;6%) at a dose of 1013 p+ cm−2 where even commercially available radiation‐hardened space PV degrade &gt;22%. Using high spatial resolution photoluminescence (PL) microscopy, it is revealed that defect clusters in GaAs are responsible for the degradation of current space‐PV. By contrast, negligible reduction in PL of the individual perovskite subcells even after the highest dose studied is observed. Studying the intensity‐dependent PL of bare low‐gap and high‐gap perovskite absorbers, it is shown that the VOC, fill factor, and efficiency potentials remain identically high after irradiation. Radiation damage of all‐perovskite tandems thus has a fundamentally different origin to traditional space PV.

Thin-film composite polyester nanofiltration membrane with high flux and efficient dye/salts separation fabricated from precise molecular sieving structure of β-cyclodextrin

The treatment of dye pollutant and salts by nanofiltration membrane technology usually has the difficulty of low permeability and higher pressure in the case of maintaining a high rejection. In this study, high flux polyester membranes of β-cyclodextrin/trimesoyl chloride - multiwalled carbon nanotubes (β-CD/TMC-MWCNTs) were fabricated on a modified multiwalled carbon nanotubes (MWCNTs) substrate via interfacial polymerization (IP) process. The modified MWCNTs substrate was not only beneficial to modulating the permeation and distribution of aqueous phase monomer (β-cyclodextrin, β-CD), but also in favor of the formation of an ultrathin loose selective polyester active layer due to the porous network structure. The optimization experiments about the reaction time and monomer concentrations were conducted. The experimental results showed that the pure water flux of the as-prepared β-CD/TMC-MWCNTs membrane was 179.93 L m-2h-1 bar-1 (at the pressure of 0.1 MPa) when the reaction time of IP process was 5 min. The single dye removal efficiency of β-CD/TMC-MWCNTs membrane was 97.41% for Brilliant Green (BG) and 96.39% for Congo red (CR), respectively. The removal efficiency of dye/salt mixture by the membrane was above 84% for BG and over 98% for CR, respectively. The results indicated that the membrane had the efficient selective separation performance for the dye/salt mixture benefiting from the special molecular sieving architectures with the precisely intrinsic inner cavity of β-CD/TMC-MWCNTs membrane. Furthermore, the reusability, chlorine resistance, and antifouling ability of the β-CD/TMC-MWCNTs membrane was relatively excellent, and the membrane could effectively remove BG (>93%) and CR (>98%) simultaneously for mixed BG/CR dyes in real water body. These results suggested that the as-prepared β-CD/TMC-MWCNTs membrane had the potential of practical application in dye wastewater treatment.

Highly Permeable Polyamide Nanofiltration Membrane Mediated by an Upscalable Wet-Laid EVOH Nanofibrous Scaffold.

For energy-saving purposes, the pursuit of ultrahigh permeance nanofiltration membranes without sacrificing selectivity is never-ending in desalination, wastewater treatment, and industrial product separation. Herein, we reported a novel facile route to engineer a highly porous and superhydrophilic nanofibrous substrate to mediate the interfacial polymerization between trimesoyl chloride and piperazine, generating an ultrathin PA active layer (∼13 nm) with a hierarchical crumpled surface. The wet laying process and subsequent plasma treatment endowed a rougher and more hydrophilic surface for ethylene vinyl alcohol copolymer (EVOH) nanofibers in the thin compact nanofibrous scaffold (∼9 μm) with a mean pore size of 210 nm, radically different from the nanofibrous membrane by other methods. Nanofibrous scaffold with these features provide abundant thin-thick alternative continuous water layers between nanofibers and organic phase, facilitating the formation of the abovementioned PA layer. As a result, an ultrahigh permeance of 42.25 L·m-2 h-1 bar-1 and a reasonably high rejection of 95.97% to 1000 ppm Na2SO4 feed solution were obtained, superior to most state-of-the-art NF membranes reported so far. Our work provides an easy and scalable method to fabricate advanced PA NF membranes with outstanding performance, highlighting its great potential in liquid separation.

10.18% PCE of organic solar cells with pyramid micron-structured PDMS

Since the light harvesting of the organic solar cells (OSCs) is limited by the ultra-thin active layer film due to the low carrier mobility of the organic materials. This study presents a tractable and cost-effective method for enhancement of the light capture of OSCs. A pyramid-shaped micron-structured polydimethylsiloxane (MST-PDMS) anti-reflection film was pasted on the back surface of the OSCs. The MST-PDMS film can reduce the reflectivity of incident light and enhance light capture. Comparing with that of the devices based on the normal indium tin oxide (ITO) glass substrates, the performance of the devices with MST-PDMS was significant improved. The size of the pyramid is an important factor to the performances of the devices. The short circuit current density could increase mostly without sacrificing the open circuit voltage and fill factor, when the width of the pyramid is 9 µm, and a maximum power conversion efficiency (PCE) of PTB7-Th: PC71BM-based OSCs reaches to 10.18%. Compared with that of the device without the anti-reflection film, PCE was increased by 17.96%. Further, the OSCs with the pyramid-shaped MST-PDMS exhibits a relatively high hydrophobic properties leading to a better stability of the devices at the ambient environment.

Designing scalable dual-layer composite hollow fiber nanofiltration membranes with fully cross-linked ultrathin functional layer

The treatment of industrial wastewater containing complex foulants demands high efficiency yet cost-effective separation process. The composite hollow fiber nanofiltration membranes suffer from tedious fabrication procedures, impeding the large volume fabrication and application. Herein, we reveal a very simplified designing strategy by polyelectrolyte modification of the co-extruded polyimide/polyethersulphone dual-layer hollow fibers with hierarchical structure and chemistry. The active layer's thickness of the dual-layer hollow fiber substrate is only 800 nm, the thinnest in literature. Compared to integral active single layer hollow fiber, the ultrathin active layer not only leads to over 4 times increase in mechanical flexibility and tenfold reduction in material cost but also enables fully chemical transition from imide to cross-linked polyamide, minimizing the intrinsic hydrolysis tendency of active material. The optimized membranes with a well-defined pore radius of 0.23 nm have 93–95% rejection to Mg2+ and Ca2+ and PWP of 9.1 LMH/bar. Moreover, the composite membranes exhibit backwash ability and stability in the heated feed solutions, which meets the demand for direct treatment of industrial effluents. This work paves the way for the large volume fabrication and application of hollow fiber nanofiltration membranes for treating municipal water, industrial wastewater, and other applications.