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A bio-based and sweat-resistant polyurethane was designed for iontronic skin. With the incorporation of a stress concentration layer and serpentine-shaped electrodes, we achieved an iontronic skin with outstanding sensitivity, stability, and portability. This technology enables precise monitoring of respiratory states in CSA, potentially mitigating complications such as sudden death. [Display omitted] • This bio-based polyurethane integrated ion-trapping, biocompatibility and sweat-resistant functionalities. • The trap-release effect coupled with stress-concentration structure significantly enhances the sensitivity. • This iontronic skin could monitor various respiratory states to prevent sudden death. Central Sleep Apnea (CSA) is characterized by respiratory pauses during sleep, posing risks like cardiovascular diseases, stroke and sudden death. The challenges in managing it arise from the current monitoring tools, which are often complicated and inaccurate. Furthermore, respiratory pauses leading to decreased blood oxygen can induce profuse sweating, further affecting accuracy. Herein, we have synthesized a bio-based, biocompatible and sweat-resistant polyurethane. By utilizing it as the matrix, we incorporated [BMIM]+[PF 6 ]− to fabricate a markedly sensitive dielectric material, termed i-DFPU. The fluorine groups in i-DFPU contributed to a trap-release effect for migratable ions, while the alkyl side chains provided smooth ion migration channels, endowing i-DFPU with exceptional sensitivity. In combination with a stress concentration layer and serpentine-shaped electrodes, the resultant iontronic skin exhibited a remarkable sensitivity up to 132.2 kPa−1, operational stability and portability. Consequently, it could accurately monitor various respiratory states in CSA, potentially preventing complications such as sudden death. [ABSTRACT FROM AUTHOR]

Emerging semiconducting materials including colloidal quantum dots (CQDs) and organic molecules have unique photovoltaic properties, and their hybridization can result in synergistic effects for high performance. For realizing the full potential of CQD/organic hybrid devices, controlling interfacial properties between the CQD and organic matter is crucial. Here, the electronic band between the CQD and the polymer layers is carefully modulated by inserting an interfacial layer treated with several types of ligands. The interfacial layer provides a cascading conduction band offset (ΔEC), and reduces local charge accumulation at CQD/polymer interfaces, thereby suppressing bimolecular recombination; a thin thiol‐treated interfacial layer (≈6 nm) decreases shallow traps, resulting in higher short‐circuit current (JSC) and fill factor of hybrid solar cells. Based on these results, a high performance CQD/polymer hybrid solar cell is introduced that demonstrates a power conversion efficiency of 13.74% under AM 1.5 solar illumination. The hybrid device retains more than 90% of its initial performance after 402 days under ambient conditions. [ABSTRACT FROM AUTHOR]

With the rapid increase in the use of optogenetics to investigate the nervous system, there is a high demand for a neural interface that enables 2D mapping of electrophysiological neural signals with high precision during simultaneous light stimulation. Here, a gold nanonetwork (Au NN)‐based transparent neural electrocorticogram (ECoG) monitoring system is proposed as implantable neural electronics. The neural interface enables accurate 2D mapping of ECoG neural signals without any photoelectric artifact during light stimulation. By using the Au NN, not only the transmittance of the microelectrodes is increased by 81% but also a low electrochemical impedance of 33.9 kΩ at 1 kHz with improved mechanical stability is achieved. It is demonstrated that the transparent microelectrode array records multichannel in vivo neural activities with no photoelectric artifact and a high signal‐to‐noise ratio. Propagation of neural dynamics of optically driven neural activities is also clearly visualized using the 2D Au NN microelectrode array. This transparent, flexible ECoG microelectrode array is a promising candidate for next‐generation in vitro and in vivo neural interface for 2D mapping of neural dynamics. [ABSTRACT FROM AUTHOR]

A tunable Fabry–Pérot resonator is realized using metal–insulator–metal structure, in which the insulator is chitosan hydrogel. The chitosan swells in response to changes in relative humidity; this change affects transmissive structural color of the multilayer structure. This tunable resonator is utilized for a humidity sensor combined with a photovoltaic cell. The change in current through the photovoltaic cell provides rapid precise measurement of relative humidity, and the change in color of the multilayer provides an approximate, remotely‐readable estimate. The response requires no power, so the device has numerous sensing applications. [ABSTRACT FROM AUTHOR]

Microalgal photosynthesis is a promising solar energy conversion process to produce high concentration biomass, which can be utilized in the various fields including bioenergy, food resources, and medicine. In this research, we study the optical design rule for microalgal cultivation systems, to efficiently utilize the solar energy and improve the photosynthesis efficiency. First, an organic luminescent dye of 3,6-Bis(4′-(diphenylamino)-1,1′-biphenyl-4-yl)-2,5-dihexyl-2,5-dihydropyrrolo3,4-c pyrrole -1,4-dione (D1) was coated on a photobioreactor (PBR) for microalgal cultivation. Unlike previous reports, there was no enhancement in the biomass productivities under artificial solar illuminations of 0.2 and 0.6 sun. We analyze the limitations and future design principles of the PBRs using photoluminescence under strong illumination. Second, as a multiple-bandgaps-scheme to maximize the conversion efficiency of solar energy, we propose a dual-energy generator that combines microalgal cultivation with spectrally selective photovoltaic cells (PVs). In the proposed system, the blue and green photons, of which high energy is not efficiently utilized in photosynthesis, are absorbed by a large-bandgap PV, generating electricity with a high open-circuit voltage (Voc) in reward for narrowing the absorption spectrum. Then, the unabsorbed red photons are guided into PBR and utilized for photosynthesis with high efficiency. Under an illumination of 7.2 kWh m−2 d−1, we experimentally verified that our dual-energy generator with C60-based PV can simultaneously produce 20.3 g m−2 d−1 of biomass and 220 Wh m−2 d−1 of electricity by utilizing multiple bandgaps in a single system. [ABSTRACT FROM AUTHOR]

Abstract: The wire grid polarizer (WGP) consisting of parallel metal nanogratings is an attractive alternative to conventional polarizers because it offers thin layer thickness, easy integration capability, and outstanding chemical and thermal stability. In this report, a facile solution process is proposed for fabricating Al WGPs. High‐aspect‐ratio Al nanostructures are formed in a 1D nanoimprinted template by electroless plating. Because of the geometrically irreversible deposition and wet etching processes on the nanotemplate, only the embedded Al nanogratings are retained. The solution‐processed Al nanostructured WGP with a line width of 60 nm and a height of 150 nm exhibits an average extinction ratio of 104 and transmittance of 52.3% in the visible wavelengths. [ABSTRACT FROM AUTHOR]

Surface-tailored ZnO nanoparticles were successfully prepared by a modified synthetic route and enables CQD:ZnO hybrid ink. Ink-process without any post-deposition process resulted in favorable heterogeneous morphology and achieved broadband photon energy conversion across visible to near-infrared. [Display omitted] • A new synthetic route successfully tailors the surface properties of ZnO NPs. • Phosphonic acid-terminated NPs successfully enable to control the surface polarity. • The stable mixed heterogenous nanocrystal ink, comprising CQD and ZnO NPs, is demonstrated. • Simple ink-process without any post-deposition process results in favorable heterogeneous morphology and shows broadband photon energy conversion across 350–1100 nm. Blending multiple functional nanoparticles (NPs) into one solvent and forming a stable hetero-ink is a promising technology to realize efficient solution-processed heterogeneous structures for next-generation energy conversion. However, differences in the surface nature of NPs hinder the formation of stable hybrid ink, causing unfavorable morphologies in film formation. In this work, we demonstrate a stable hybrid ink using colloidal quantum dots (CQDs) and metal-oxide NPs. The modified synthesis route of ZnO NPs enables modulation of their surfaces, resulting in ink that is fully miscible in alkyl amine solvents with CQDs. This hybrid ink allows the formation of conformal heterogeneous thin-films via a single step spin-casting. Based on this result, we devise an efficient planar-mixed heterojunction solar cell, which exhibits a 12.8% power conversion efficiency (PCE), one of the highest performances among prior CQD:metal-oxide hetero-structured hybrid solar cells. [ABSTRACT FROM AUTHOR]

We present our efforts to enhance the stability of normal-geometry organic solar cells (n-OSCs), which are generally considered inferior to their inverted-geometry counterparts in terms of stability. Upon the identification of the vulnerability of top electrode/buffer layer interfaces under a humid environment, various top electrode combinations are assessed under an extremely damp condition (27 °C, 90%) for n-OSCs based on a bulk-heterojunction of poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C70-butyric acid methylester (PCBM70). Based on the experimental results, we propose an Al/Cu bilayer top electrode and demonstrate a 30-fold enhancement in the T 80 -lifetime values. Our study reveals that the enhanced lifetime with an Al/Cu bilayer electrode can be attributed to its water vapor transmission rate (WVTR), which is significantly lower than that of the Al electrodes typically used in conventional organic solar cells. The enhanced normal OSCs yielded stability comparable to that of the previously reported inverted OSCs. [ABSTRACT FROM AUTHOR]

The potential of hybrid perovskite/organic solar cells (HSCs) is increasingly recognized owing to their advantageous characteristics, including straightforward fabrication, broad-spectrum photon absorption, and minimal open-circuit voltage (V OC ) loss. Nonetheless, a key bottleneck for efficiency improvement is the energy level mismatch at the perovskite/bulk-heterojunction (BHJ) interface, leading to charge accumulation. In this study, it is demonstrated that introducing a uniform sub-nanometer dipole layer formed of B3PyMPM onto the perovskite surface effectively reduces the 0.24 eV energy band offset between the perovskite and the donor of BHJ. This strategic modification suppresses the charge recombination loss, resulting in a noticeable 30 mV increase in the V OC and a balanced carrier transport, accompanied by a 5.0% increase in the fill factor. Consequently, HSCs that achieve power conversion efficiency of 24.0% is developed, a new record for Pb-based HSCs with a remarkable increase in the short-circuit current of 4.9 mA cm -2 , attributed to enhanced near-infrared photon harvesting., (© 2024 Wiley‐VCH GmbH.)

In this study, we examined the nanostructured molecular packing and orientations of poly[[ N , N '-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt -5,5'-(2,2'-bithiophene)] (P(NDI2OD-T2)) films formed on water for the application of nanotechnology-based organic electronic devices. First, the nanoscale molecule-substrate interaction between the polymer and water was modulated by controlling the alkyl side chain length in NDI-based copolymers. Increasing alkyl side chain lengths induced a nanomorphological transition from face-on to edge-on orientation, confirmed by molecular dynamics simulations revealing nanostructural behavior. Second, the nanoscale intermolecular interactions of P(NDI2OD-T2) were controlled by varying the volume ratio of the high-boiling-point additive solvent in the binary solvent blends. As the additive solvent ratio increased, the nanostructured molecular orientation of the P(NDI2OD-T2) films on water changed remarkably from edge-on to bimodal with more face-on crystallites, thereby affecting charge transport. Our finding provides essential insights for precise nanoscale morphological control on water substrates, enabling the formation of high-performance polymer films for organic electronic devices.

Deep-blue perovskite light-emitting diodes (PeLEDs) of high purity are highly sought after for next-generation displays complying with the Rec. 2020 standard. However, mixed-halide perovskite materials designed for deep-blue emitters are prone to halide vacancies, which readily occur because of the low formation energy of chloride vacancies. This degrades bandgap instability and performance. Here, we propose a chloride vacancy-targeting passivation strategy using sulfonate ligands with different chain lengths. The sulfonate groups have a strong affinity for lead(II) ions, effectively neutralizing vacancies. Our strategy successfully suppressed phase segregation, yielding color-stable deep-blue PeLEDs with an emission peak at 461 nanometers and a maximum luminance ( L max ) of 2707 candela per square meter with external quantum efficiency (EQE) of 3.05%, one of the highest for Rec. 2020 standard-compliant deep-blue PeLEDs. We also observed a notable increase in EQE up to 5.68% at L max of 1978 candela per square meter with an emission peak at 461 nanometers by changing the carbon chain length.

Lead sulfide (PbS) colloidal quantum dots (CQDs) are promising materials for next-generation flexible solar cells because of near-infrared absorption, facile bandgap tunability, and superior air stability. However, CQD devices still lack enough flexibility to be applied to wearable devices owing to the poor mechanical properties of CQD films. In this study, a facile approach is proposed to improve the mechanical stability of CQDs solar cells without compromising the high power conversion efficiency (PCE) of the devices. (3-aminopropyl)triethoxysilane (APTS) is introduced on CQD films to strengthen the dot-to-dot bonding via QD-siloxane anchoring, and as a result, crack pattern analysis reveals that the treated devices become robust to mechanical stress. The device maintains 88% of the initial PCE under 12 000 cycles at a bending radius of 8.3 mm. In addition, APTS forms a dipole layer on CQD films, which improves the open circuit voltage (V OC ) of the device, achieving a PCE of 11.04%, one of the highest PCEs in flexible PbS CQD solar cells., (© 2023 Wiley-VCH GmbH.)

Hybrid colloidal quantum dot (CQD)/organic architectures are promising candidates for emerging optoelectronic devices having high performance and inexpensive fabrication. For unlocking the potential of CQD/organic hybrid devices, enhancing charge extraction properties at electron transport layer (ETL)/CQD interfaces is crucial. Hence, we carefully adjust the interface properties between the ETL and CQD layer by incorporating an interfacial layer for the ETL (EIL) using several types of cinnamic acid ligands. The EIL having a cascading band offset ( ΔE C ) between the ETL and CQD layer suppresses the potential barrier and the local charge accumulation at ETL/CQD interfaces, thereby reducing the bimolecular recombination. An optimal EIL effectively expands the depletion region that facilitates charge extraction between the ETL and CQD layer while preventing the formation of shallow traps. Representative devices with an EIL exhibit a maximum power conversion efficiency of 14.01% and retain over 80% of initial performances after 300 h under continuous maximum power point operation.

Recurrent implantation failure (RIF) refers to two or more unsuccessful in vitro fertilization embryo transfers in the same individual. Embryonic characteristics, immunological factors, and coagulation factors are known to be the causes of RIF. Genetic factors have also been reported to be involved in the occurrence of RIF, and some single nucleotide polymorphisms (SNPs) may contribute to RIF. We examined SNPs in FSHR , INHA , ESR1 , and BMP15 , which have been associated with primary ovarian failure. A cohort of 133 RIF patients and 317 healthy controls consisting of all Korean women was included. Genotyping was performed by Taq-Man genotyping assays to determine the frequency of the following polymorphisms: FSHR rs6165, INHA rs11893842 and rs35118453, ESR1 rs9340799 and rs2234693, and BMP15 rs17003221 and rs3810682. The differences in these SNPs were compared between the patient and control groups. Our results demonstrate a decreased prevalence of RIF in subjects with the FSHR rs6165 A>G polymorphism [AA vs. AG adjusted odds ratio (AOR) = 0.432; confidence interval (CI) = 0.206-0.908; p = 0.027, AA+AG vs. GG AOR = 0.434; CI = 0.213-0.885; p = 0.022]. Based on a genotype combination analysis, the GG/AA ( FSHR rs6165/ESR1 rs9340799: OR = 0.250; CI = 0.072-0.874; p = 0.030) and GG-CC ( FSHR rs6165/ BMP15 rs3810682: OR = 0.466; CI = 0.220-0.987; p = 0.046) alleles were also associated with a decreased RIF risk. Additionally, the FSHR rs6165GG and BMP15 rs17003221TT+TC genotype combination was associated with a decreased RIF risk (OR = 0.430; CI = 0.210-0.877; p = 0.020) and increased FSH levels, as assessed by an analysis of variance. The FSHR rs6165 polymorphism and genotype combinations are significantly associated with RIF development in Korean women.

The corrosion mechanism and kinetics of the silver-coated conductive yarn (SCCY) used for wearable electronics were investigated under a NaCl solution, a main component of sweat. The corrosion occurs according to the mechanism in which silver reacts with chlorine ions to partly form sliver chloride on the surface of the SCCY and then the local silver chloride is detached into the electrolyte, leading to the electrical disconnect of the silver coating. Thus, the electrical conductance of the SCCY goes to zero after 2.7 h. The radial part-coating of gold, which is continuously electrodeposited in the longitudinal direction on the SCCY but is partly electrodeposited in the radial direction, extends the electrical conducting lifetime up to 192 h, despite the corrosion rate increasing from 129 to 196 mpy (mils per year). Results show that the gold partly-coating on the SCCY provides a current path for electrical conduction along the longitudinal direction until all the silver underneath the gold coating is detached from the SCCY strands, which creates the electrical disconnect. Based on the corrosion behavior, i.e., local oxidation and detachment of silver from the SCCY, the gold part-coating is more cost effective than the gold full-coating electrodeposited on the entire surface for electrically conducting SCCY., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Park, Park, Jeong, Lee and Song.)

Liquid metals are attractive materials for stretchable electronics owing to their high electrical conductivity and near-zero Young's modulus. However, the high surface tension of liquid metals makes it difficult to form films. A novel stretchable film is proposed based on an over-layered liquid-metal network. An intentionally oxidized interfacial layer helps to construct uninterrupted indium and gallium nanoclusters and produces additional electrical pathways between the two metal networks under mechanical deformation. The films exhibit gigantic negative piezoresistivity (G-NPR), which decreased the resistance up to 85% during the first 50% stretching. This G-NPR property is due to the rupture of the metal oxides, which allows the formation of liquid eutectic gallium-indium (EGaIn) and the connection of the over-layered networks to build new electrical paths. The electrodes exhibiting G-NPR are complementarily combined with conventional electrodes to amplify their performance or achieve some unique operations., (© 2023 Wiley-VCH GmbH.)

Intrinsically stretchable organic solar cells (IS-OSCs), consisting of all stretchable layers, are attracting significant attention as a future power source for wearable electronics. However, most of the efficient active layers for OSCs are mechanically brittle due to their rigid molecular structures designed for high electrical and optical properties. Here, a series of new polymer donors (P D s, PhAmX) featuring phenyl amide (N 1 ,N 3 -bis((5-bromothiophen-2-yl)methyl)isophthalamide, PhAm)-based flexible spacer (FS) inducing hydrogen-bonding (H-bonding) interactions is developed. These P D s enable IS-OSCs with a high power conversion efficiency (PCE) of 12.73% and excellent stretchability (PCE retention of >80% of the initial value at 32% strain), representing the best performances among the reported IS-OSCs to date. The incorporation of PhAm-based FS enhances the molecular ordering of P D s as well as their interactions with a Y7 acceptor, enhancing the mechanical stretchability and electrical properties simultaneously. It is also found that in rigid OSCs, the PhAm5:Y7 blend achieves a much higher PCE of 17.5% compared to that of the reference PM6:Y7 blend. The impact of the PhAm-FS linker on the mechanical and photovoltaic properties of OSCs is thoroughly investigated., (© 2022 Wiley-VCH GmbH.)

Recent advances in the power conversion efficiency (PCE) of organic solar cells (OSCs) have greatly enhanced their commercial viability. Considering the technical standards (e.g., mechanical robustness) required for wearable electronics, which are promising application platforms for OSCs, the development of fully stretchable OSCs (f-SOSCs) should be accelerated. Here, a comprehensive overview of f-SOSCs, which are aimed to reliably operate under various forms of mechanical stress, including bending and multidirectional stretching, is provided. First, the mechanical requirements of f-SOSCs, in terms of tensile and cohesion/adhesion properties, are summarized along with the experimental methods to evaluate those properties. Second, essential studies to make each layer of f-SOSCs stretchable and efficient are discussed, emphasizing strategies to simultaneously enhance the photovoltaic and mechanical properties of the active layer, ranging from material design to fabrication control. Key improvements to the other components/layers (i.e., substrate, electrodes, and interlayers) are also covered. Lastly, considering that f-SOSC research is in its infancy, the current challenges and future prospects are explored., (© 2022 Wiley-VCH GmbH.)

Highly efficient vacuum-deposited CsPbBr 3 perovskite light-emitting diodes (PeLEDs) are demonstrated by introducing a separate polyethylene oxide (PEO) passivation layer. A CsPbBr 3 film deposited on the PEO layer via thermal co-evaporation of CsBr and PbBr 2 exhibits an almost 50-fold increase in photoluminescence quantum yield intensity compared to a reference sample without PEO. This enhancement is attributed to the passivation of interfacial defects of the perovskite, as evidenced by temperature-dependent photoluminescence measurements. However, direct application of PEO to an LED device is challenging because of the electrically insulating nature of PEO. This issue is solved by doping PEO layers with MgCl 2 . This strategy results in an enhanced luminance and external quantum efficiency (EQE) of up to 6887 cd m -2 and 7.6%, respectively. To the best of our knowledge, this is the highest EQE reported to date among vacuum-deposited PeLEDs.

Despite the excellent electrical conductivity of metal thin film electrodes, their poor mechanical stretchability makes it extremely difficult to apply them as stretchable interconnect electrodes. Thus, we propose a novel stretchable hybrid electrode (SHE) by adopting two strategies to overcome the metal thin film electrode limitations: grain size engineering and hybridization with conductive interlayers. The grain size engineering technique improves the inherent metal thin film stretchability according to the Hall-Petch theory, and the hybridization of the conductive interlayer materials, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and carbon nanotube (CNT), suppresses crack propagation. Especially, the CNT-inserted SHE exhibits a decreased resistance change of approximately 32% in tensile test and 75% in a 10 000 cycle fatigue test because of the rough surface of the designed electrode, which relieves maximum stress by redistributing it more evenly to prevent penetrating crack propagation.

Colloidal quantum dots (CQDs) have large surface-to-volume ratios; thus, surface control is critical, especially when CQDs are utilized in optoelectronic devices. Layer-by-layer solid-state ligand exchange is a facile and applicable process for the formation of conductive CQD solids through various ligands; however, achieving complete ligand exchange on the CQD surface without dangling bonds is challenging. Herein, we demonstrate that CQDs can be further passivated through two-step annealing; air annealing forms sulfonate bonding at (111) Pb-rich surfaces, and subsequent N 2 annealing removes insulating oxygen layers from the (100) surfaces of CQDs. By subsequently conducting annealing treatment in two different environments, traps on the surface of CQDs could be significantly reduced. We achieved a 40.8% enhancement of the power conversion efficiency by optimizing each two-step annealing process.

This study proposes a reliable and self-powered hydrogen (H 2 ) gas sensor composed of a chemo-mechanically operating nanostructured film and photovoltaic cell. Specifically, the nanostructured film has a configuration in which an asymmetrically coated palladium (Pd) film is coated on a periodic polyurethane acrylate (PUA) nanograting. The asymmetric Pd nanostructures, optimized by a finite element method simulation, swell upon reacting with H 2 and thereby bend the PUA nanograting, changing the amount of transmitted light and the current output of the photovoltaic cell. Since the degree of warping is determined by the concentration of H 2 gas, a wide concentration range of H 2 (0.1-4.0%) can be detected by measuring the self-generated electrical current of the photovoltaic cell without external power. The normalized output current changes are ∼1.5%, ∼2.8%, ∼3.5%, ∼5.0%, ∼21.5%, and 25.3% when the concentrations of H 2 gas are 0.1%, 0.5%, 1.0%, 1.6%, 2%, and 4%, respectively. Moreover, because Pd is highly chemically reactive to H 2 and also because there is no electrical current applied through Pd, the proposed sensor can avoid device failure due to the breakage of the Pd sensing material, resulting in high reliability, and can show high selectivity against various gases such as carbon monoxide, hydrogen sulfide, nitrogen dioxide, and water vapor. Finally, using only ambient visible light, the sensor was modularized to produce an alarm in the presence of H 2 gas, verifying a potential always-on H 2 gas monitoring application.

Metal nanowires (NWs) are promising transparent conducting electrode (TCE) materials because of their excellent optoelectrical performance, intrinsic mechanical flexibility, and large-scale processability. However, the surface roughness, thermal/chemical instability, and limited electrical conductivity associated with empty spaces between metal NWs are problems that are yet to be solved. Here, we report a highly reliable and robust composite TCE/substrate all-in-one platform that consists of crystalline indium tin oxide (c-ITO) top layer and surface-embedded metal NW (c-ITO/AgNW-GFRH) films for flexible optoelectronics. The c-ITO top layer (thickness: 10-30 nm) greatly improves the electrical performance of a AgNW-based electrode, retaining its transparency even after a high-temperature annealing process at 250 °C because of its thermally stable basal substrate (i.e., AgNW-GFRH). By introducing c-ITO thin film, we achieve an extremely smooth surface ( R rms < 1 nm), excellent optoelectrical performance, superior thermal (> 250 °C)/chemical stability (in sulfur-contained solution), and outstanding mechanical flexibility (bending radius = 1 mm). As a demonstration, we fabricate flexible organic devices (organic photovoltaic and organic light-emitting diode) on c-ITO/AgNW-GFRH films that show device performance comparable to that of references ITO/glass substrates and superior mechanical flexibility. With excellent stability and demonstrations, we expect that the c-ITO/AgNW-GFRHs can be used as flexible TCE/substrate films for future thin-film optoelectronics.

We report a new type of self-powered gas sensors based on the combination of a colorimetric film with hierarchical micro/nanostructures and organic photovoltaic cells. The transmittance of the colorimetric film with micro/nanostructures coated with N , N , N ', N '-tetramethyl- p -phenylenediamine (TMPD) changes by reacting with NO 2 gas, and it is measured as a current output of the photovoltaic cell. For this purpose, materials for the organic photovoltaic cells were carefully chosen to match the working wavelength of the TMPD. Micropost arrays and nanowires increase the surface area for the gas reaction and thus improve the transmittance changes by NO 2 gas (6.7% change for the plain film vs 27.7% change for the film with hierarchical micro/nanostructures to 20 ppm of NO 2 ). Accordingly, the colorimetric device with the hierarchical structures showed a response of Δ I / I 0 = 0.27-20 ppm of NO 2 , which is a 71% improvement compared to that of the plain sensing film. Furthermore, it showed a high selectivity against other gases such as H 2 S and CO with almost negligible responses. Since the current output change of the photovoltaic cell is utilized as a sensor signal, no extra electrical power is required for the operation of gas sensors. We also integrated the sensor device with an electrical module and demonstrated a self-powered gas alarm system.

Metallic thin films often exhibit poor mechanical robustness, which makes them unsuitable for use as electrodes in flexible and stretchable electronic devices. This prompted us to investigate the effect of creating a pattern of nanoholes in a metallic thin film to its mechanical and electrical properties. The adoption of nanonetwork structures is shown to confer significantly improved bendability to the films, with a change in electrical resistance of only 21% after 10 000 bending cycles, under a bending strain of 6.3%. In contrast to the planar silver (Ag) films in which large cracks are formed, structures that contain nanoholes act as barriers that block the growth of cracks; consequently, only short cracks are formed in these films and therefore changes in their resistance are much lower. In this paper, we suggest a novel model based on random grain boundaries to simulate the behavior of various nanopattern arrangements when the film is subjected to mechanical stress. Our modeling studies revealed that nanoholes secure the electrical current pathways by effectively blocking crack propagation, and that optimizing orientation, size, and coverage of these nanoholes can further improve the mechanical properties. Although diamond patterns exhibit superior characteristics to those of rectangular ones, their directional dependence is shown to be reduced by adopting randomly dispersed nanostructures. We additionally verified experimentally that an array of holes (rectangular, diamond-shaped, and randomly patterned) significantly affects crack propagation and resistance change.

The facile sequential deposition of functional organic thin films by solution processes is critical for the development of a variety of high-performance organic devices without restriction in terms of materials and processes. Herein, we propose a simple fabrication process that entails stacking multiple layers of functional polymers to fabricate organic field-effect transistors (OFETs). The process involves stamping organic semiconducting layers formed on the surface of water onto a commonly used polymeric dielectric layer. Our scheme makes it possible to independently optimize organic semiconductor films by controlling the solvent evaporation time during the process of film formation on the surface of water. This approach eliminates the need to be concerned about any interference with adjacent layers. Utilizing this process, the fabrication of high-performance bottom-gated OFETs is demonstrated on a glass and a flexible substrate. The OFETs consist of a vertically stacked diketopyrrolopyrrole-based polymer semiconducting layer on the poly(methyl methacrylate) film with a maximum hole mobility of 0.85 cm 2 /V s.

Perovskite light-emitting diodes have recently broken the 20% barrier for external quantum efficiency. These values cannot be explained with classical models for optical outcoupling. Here, we analyse the role of photon recycling (PR) in assisting light extraction from perovskite light-emitting diodes. Spatially-resolved photoluminescence and electroluminescence measurements combined with optical modelling show that repetitive re-absorption and re-emission of photons trapped in substrate and waveguide modes significantly enhance light extraction when the radiation efficiency is sufficiently high. In this manner, PR can contribute more than 70% to the overall emission, in agreement with recently-reported high efficiencies. While an outcoupling efficiency of 100% is theoretically possible with PR, parasitic absorption losses due to absorption from the electrodes are shown to limit practical efficiencies in current device architectures. To overcome the present limits, we propose a future configuration with a reduced injection electrode area to drive the efficiency toward 100%.

In this study, we report a homo-tandem structure of small molecular organic solar cells (SMOSCs) using identical single-junction devices as sub-cells. The trade-off between the absorption and internal quantum efficiency (IQE) of single-junction devices tends to limit the external quantum efficiency (EQE). However, multiple-stacked thin cells with maximized IQE in homo-tandem structures amplify the absorption to achieve the ideal EQE. As a result, a high power conversion efficiency of 7.81% is achieved in tetraphenyldibenzoperiflanthene (DBP):C 70 -based homo-tandem SMOSCs, which is 21.8% higher than that in a single-junction device.

A novel self-charging platform is proposed using colloidal-quantum-dot (CQD) photovoltaics (PVs) via the near-infrared (NIR) band for low-power electronics. Low-bandgap CQDs can convert invisible NIR light sources to electrical energy more efficiently than wider spectra because of reduced thermalization loss. This energy-conversion strategy via NIR photons ensures an enhanced photostability of the CQD devices. Furthermore, the NIR wireless charging system can be concealed using various colored and NIR-transparent fabric or films, providing aesthetic freedom. Finally, an NIR-driven wireless charging system is demonstrated for a wearable healthcare bracelet by integrating a CQD PVs receiver with a flexible lithium-ion battery and entirely embedding them into a flexible strap, enabling permanent self-charging without detachment., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein, a new methodology for solution-processed ZnO fabrication on Ag nanowire network electrode via combustion reaction is reported, where the amount of heat emitted during combustion was minimized by controlling the reaction temperature to avoid damaging the underlying Ag nanowires. The degree of participation of acetylacetones, which are volatile fuels in the combustion reaction, was found to vary with the reaction temperature, as revealed by thermogravimetric and compositional analyses. An optimized processing temperature of 180 °C was chosen to successfully fabricate a combustion-reacted ZnO and Ag nanowire hybrid electrode with a sheet resistance of 30 Ω/sq and transmittance of 87%. A combustion-reacted ZnO on Ag nanowire hybrid structure was demonstrated as an efficient transparent electrode and electron transport layer for the PTB7-Th-based polymer solar cells. The superior electrical conductivity of combustion-reacted ZnO, compared to that of conventional sol-gel ZnO, increased the external quantum efficiency over the entire absorption range, whereas a unique light scattering effect due to the presence of nanopores in the combustion-derived ZnO further enhanced the external quantum efficiency in the 450-550 nm wavelength range. A power conversion efficiency of 8.48% was demonstrated for the PTB7-Th-based polymer solar cell with the use of a combustion-reacted ZnO/Ag NW hybrid transparent electrode.

We investigate the arrangement of donor molecules in vacuum-deposited bulk heterojunction (BHJ) 1,1-bis-(4-bis(4-methyl-phenyl)-amino-phenyl)-cyclohexane (TAPC):C 70 -based organic solar cells (OSCs). Even a low dose of donors (∼10%) forms columnar structures that provide pathways for efficient hole transport in the BHJ layer; however, these structures disappear at donor concentrations below 10%, generating disconnected and isolated hole pathways. The formation of columnar donor structures is confirmed by the contrast of the contact potential difference, measured by Kelvin probe force microscopy, and by the trap-assisted charge injection at low donor concentrations. The mobility of electrons and holes is well balanced in OSCs owing to the preservation of the hole mobility at such low donor concentrations, consequently maximizing the internal quantum efficiency of the OSCs. A high power conversion efficiency of 6.24% was achieved in inverted TAPC:C 70 (1:9) OSCs., Competing Interests: The authors declare no competing financial interest.

Bandgap tunability and broadband absorption make quantum-dot (QD) photovoltaic cells (PVs) a promising candidate for future solar energy conversion systems. Approaches to improving the electrical properties of the active layer increase efficiency in part. The present study focuses on optical room for enhancement in QD PVs over wide spectrum in the near-infrared (NIR) region. We find that ray-optical light trapping schemes rather than the nanophotonics approach may be the best solution for enhancing broadband QD PVs by suppressing the escape probability of internal photons without spectral dependency. Based on the theoretical study of diverse schemes for various bandgaps, we apply a V-groove structure and a V-groove textured compound parabolic trapper (VCPT) to PbS-based QD PVs along with the measurement issues for PVs with a light scattering layer. The efficiency of the best device is improved from 10.3% to 11.0% (certified to 10.8%) by a V-groove structure despite the possibility of underestimation caused by light scattering in small-area devices (aperture area: 0.0625 cm 2 ). By minimizing such underestimation, even greater enhancements of 13.6% and 15.6% in short circuit current are demonstrated for finger-type devices (0.167 cm 2 without aperture) and large-area devices (2.10 cm 2 with an aperture of 0.350 cm 2 ), respectively, using VCPT.

Generating syngas (H 2 and CO mixture) from electrochemically reduced CO 2 in an aqueous solution is one of the sustainable strategies utilizing atmospheric CO 2 in value-added products. However, a conventional single-component metal catalyst, such as Ag, Au, or Zn, exhibits potential-dependent CO 2 reduction selectivity, which could result in temporal variation of syngas composition and limit its use in large-scale electrochemical syngas production. Herein, we demonstrate the use of Ag nanowire (NW)/porous carbon sheet composite catalysts in the generation of syngas with tunable H 2 /CO ratios having a large potential window to resist power fluctuation. These Ag NW/carbon sheet composite catalysts have a potential window increased by 10 times for generating syngas with the proper H 2 /CO ratio (1.7-2.15) for the Fischer-Tropsch process and an increased syngas production rate of about 19 times compared to that of a Ag foil. Additionally, we tuned the H 2 /CO ratio from ∼2 to ∼10 by adjusting only the quantity of the Ag NWs under the given electrode potential. We believe that our Ag NW/carbon sheet composite provides new possibilities for designing electrode structures with a large potential window and controlled CO 2 reduction products in aqueous solutions., Competing Interests: The authors declare no competing financial interest.

Previous molecular genetic studies of laryngeal squamous cell carcinoma (SCC)have shown certain chromosomal regions with recurring alterations. But studies of sequential molecular alterations and genetic progression model of laryngeal SCC have not been clearly defined. To identify the chromosomal alterations associated with the carcinogenesis of laryngeal SCC, we analyzed genomic DNA from microdissected squamous metaplasia, squamous dysplasia, invasive SCC, and metastatic carcinoma samples from 22 laryngeal SCC patients for loss of heterozygosity (LOH) at microsatellite loci. Ten microsatellite markers on chromosome 3p, 8p, 9p, and 17p were used. LOH at 9p21 was observed in the all stages including squamous metaplasia, squamous dysplasia, invasive SCC and metastatic carcinoma. LOH at 17p13.1, 3p25 and 3p14.2 was observed from the squamous dysplasia, invasive SCC and metastatic carcinoma. LOH at 8p21.3-p22 was observed mainly from the invasive SCC and metastatic carcinoma. The results suggest that 9p21 in the early event, 17p13.1, 3p25 and 3p14.2 in the intermediate event and 8p21.3- p22 in the late event may be involved in the laryngeal carcinogenesis.