Search

To investigate changes in the chemical composition of malts under different germination cycles and prepared with different processing methods, thus providing a reference for the clinical application of malt in disease treatment.Nine malt samples were analyzed by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS), and the MS fragmentation pathway of 4 compounds (including hordenine, gramine, N-methyltyramine and catechin) were also analyzed.By database comparison and literature search, we detected 31 compounds in raw barley and 33 compounds in both raw malt and roasted malt. Nonetheless, the most of these 33 compounds were detected higher contents in raw malt than in roasted malt. Besides, we detected 15 compounds in brown malt. At Day1 of germination, 31 compounds were detected in malt, without two alkaloids (representative: hordenine). At Day2-5, 33 compounds were detected, with different contents as shown by the peak area comparison; hordenine had a gradually increasing abundance; and nearly one third of the chemical components in barley increased gradually, one third decreased gradually, and one third tended to be stable.Malts under different germination cycles and prepared with different processing methods have varying active ingredients, and especially brown malt exhibits a serious loss of compounds. The tight association between the chemical composition and clinical application of malt offers a basis to the clinically scientific and reasonable selection of Chinese medicinal materials for treatment purposes.

Wide-band-gap layered semiconductor hexagonal boron nitride (h-BN) is attracting intense interest due to its unique optoelectronic properties and versatile applications in deep ultraviolet optoelectronic and two-dimensional electronic devices. However, it is still a great challenge to directly grow high-quality h-BN on dielectric substrates, and an extremely high substrate temperature or annealing is usually required. In this work, high-quality few-layer h-BN is directly grown on sapphire substrates via ion beam sputtering deposition at a relatively low temperature of 700 °C by introducing NH

Perovskite light-emitting diodes (PeLEDs) have showed significant progress in recent years; the external quantum efficiency (EQE) of electroluminescence in green and red regions has exceeded 20%, but the efficiency in blue lags far behind. Here, a large cation CH3CH2NH2+ is added in PEA2(CsPbBr3)2PbBr4 perovskite to decrease the Pb–Br orbit coupling and increase the bandgap for blue emission. X-ray diffraction and nuclear magnetic resonance results confirmed that the EA has successfully replaced Cs+ cations to form PEA2(Cs1-xEAxPbBr3)2PbBr4. This method modulates the photoluminescence from the green region (508 nm) into blue (466 nm), and over 70% photoluminescence quantum yield in blue is obtained. In addition, the emission spectra is stable under light and thermal stress. With configuration of PeLEDs with 60% EABr, as high as 12.1% EQE of sky-blue electroluminescence located at 488 nm has been demonstrated, which will pave the way for the full color display for the PeLEDs., Blue light-emitting diodes (LEDs) are critical for displays. Employing a large organic cation into a quasi-two dimensional perovskite with green emission, Chu et al. achieve LEDs exhibiting a high external quantum efficiency of 12.1% and stable spectra in the sky-blue region.

Recently, the deep ultraviolet (DUV) photodetectors fabricated from two-dimensional (2D) hexagonal boron nitride (h-BN) layers have emerged as a hot research topic. However, the existing studies show that the h-BN-based photodetectors have relatively poor performance. In this work, C doping is utilized to modulate the properties of h-BN and improve the performance of the h-BN-based photodetectors. We synthesized the h-BN atomic layers with various C concentrations varying from 0 to 10.2 atom % by ion beam sputtering deposition through controlling the sputtering atmosphere. The h-BN phase remains stable when a small amount of C is incorporated into h-BN, whereas the introduction of a large amount of C impurities leads to the rapidly deteriorated crystallinity of h-BN. Furthermore, the DUV photodetectors based on C-doped h-BN layers were fabricated, and the h-BN-based photodetector with 7.5 atom % C exhibits the best performance with a responsivity of 9.2 mA·W-1, which is significantly higher than that of the intrinsic h-BN device. This work demonstrates that the C doping is a feasible and effective method for improving the performance of h-BN photodetectors.

Surface plasmonic effect of metal nanoparticles is an effective method to improve the power conversion efficiency (PCE) of solar cells. In this work, the PCE of bulk heterojunction (BHJ) polymer solar cells was improved by Au nanoparticles (NPs). The Au NPs were embedded into PEDOT:PSS hole transport layer by spin coating on the ITO substrates. The Au NPs with a diameter of ~16 nm were prepared by the micellar method using polystyrene-block-poly (2-vinylpyridine) diblock polymer. The Au NPs prepared by this method are distributed uniformly in size and without agglomeration on the substrates. From both experimental and theoretical results, it can be seen that the light absorption of the active layer was increased because of the surface plasmonic effect of Au NPs. Meanwhile, the carrier transport performance of PEDOT:PSS was enhanced with introduced Au NPs. As a result, the PCE of BHJ solar cells was improved from 2.81 to 3.25% by incorporating Au NPs.

Background To determine the efficacy and safety of umbilical cord-derived mesenchymal stem cells (UC-MSCs) in Chinese adults with type 2 diabetes mellitus (T2DM). Methods In this single-center, double-blinded, randomized, placebo-controlled phase II trial, 91 patients were randomly assigned to receive intravenous infusion of UC-MSCs (n = 45) or placebo (n = 46) three times with 4-week intervals and followed up for 48 weeks from October 2015 to December 2018. The primary endpoint was the percentage of patients with glycated hemoglobin (HbA1c) levels of Results At 48 weeks, 20% of the patients in the UC-MSCs group and 4.55% in the placebo group reached the primary endpoint (p p p p˃0.05; p = 0.0081 between both groups). The glucose infusion rate (GIR) increased significantly in the UC-MSCs group (from 3.12 to 4.76 mg/min/kg, p p ˃ 0.05; p Conclusions UC-MSCs transplantation could be a potential therapeutic approach for Chinese adults with T2DM. Trial registration This study was registered on ClinicalTrials.gov (identifier: NCT02302599).

Malt is the mature fruit of Hordeum vulgare L. after germination and drying and has been applied for treatment female abnormal galactorrhea. Previous studies have showed total alkaloids in malt have anti-HPRL effect. However, total alkaloids of malt change with the growth cycle, and the specified levels of total alkaloids in different bud length of malt have not been decided. To determine the definitive level of total alkaloids in different buds of malt and the most suitable bud length for clinical application by comparing effects on hyperprolactinemia rat. During the budding of malt, the content of total alkaloids first increased and then decreased, and it peaked at a bud length of 0.75 cm. Treated the HPRL model rats with different buds of malt, the PRL level was decreased, the number of PRLpositive cells and the mRNA expression level in the pituitary were significantly declined, and the number of dopamine D1 and D2 receptors in the hypothalamus was increased. The above changes were most significant in 0.75 cm bud. These results suggest that in terms of the content of effective substance and the effects on HPRL model rats, a malt bud length of 0.75 cm is optimal for clinical application.

The behavior of H in β-Ga2O3 is of substantial interest because it is a common residual impurity that is present in β-Ga2O3, regardless of the synthesis methods. Herein, we report the influences of H-plasma exposure on the electric and optical properties of the heteroepitaxial β-Ga2O3 thin films grown on sapphire substrates by chemical vapor deposition. The results indicate that the H incorporation leads to a significantly increased electrical conductivity, a greatly reduced defect-related photoluminescence emission, and a slightly enhanced transmittance, while it has little effect on the crystalline quality of the β-Ga2O3 films. The significant changes in the electrical and optical properties of β-Ga2O3 may originate from the formation of shallow donor states and the passivation of the defects by the incorporated H. Temperature dependent electrical properties of the H-incorporated β-Ga2O3 films are also investigated, and the dominant scattering mechanisms at various temperatures are discussed.

Quasi-two-dimensional (quasi-2D) perovskites are efficient luminescent materials due to their self-assembled quantum-well structure. We found that the organic cations have a significant effect on the structure and performance of quasi-2D perovskite-based light-emitting diodes (LEDs). Two classic organic cations, formamidinium (FA) and methylammonium (MA), were chosen for investigation. The MA-based quasi-2D perovskite has the largest band-gap n = 1 phase and a photoluminescence quantum yield (PLQY) as high as 85.3%, whereas this n = 1 phase is almost absent in the FA-based quasi-2D perovskite, which shows a moderate PLQY of 73.5%. However, the FA-based perovskite shows a much higher external quantum efficiency (15.4%) than the MA-based perovskite (0.93%) in LEDs. The lower electroluminescence efficiency of the MA-based perovskite could be ascribed to the poor hole injection. These results showed the importance of rational design of the quasi-2D perovskite for efficient LEDs.

Two-dimensional (2D) hexagonal boron nitride (h-BN) is a promising candidate as a supporting substrate, a gate dielectric and a protecting layer for 2D electronic and photonic devices. Transition metals were usually adopted as substrates for the synthesis of 2D h-BN, however, catalyst-free growth of high-quality h-BN on dielectric substrates is still very challenging. Herein, we report the catalyst-free growth of 2D h-BN few-layers on sapphire substrates by ion beam sputtering deposition (IBSD). We find that the h-BN grown under conventional conditions is nonstoichiometric with an excess of B element, resulting in a large number of N vacancy defects and poor crystalline quality. The wafer-scale high quality 2D h-BN layers were synthesized on sapphire by the combination of surface nitridation and N+ sputtering. Furthermore, the 2D h-BN few-layers on sapphire were used to fabricate deep ultraviolet photodetectors, which exhibit better performance in comparison with the devices fabricated by the transferred h-BN.

Two-dimensional (2D) hexagonal boron-carbon-nitrogen (h-BCN) atomic layers are expected to possess interesting properties complementary to those of graphene and h-BN, enabling a rich variety of electronic structures, properties and applications. Herein, we demonstrate a novel method to synthesize 2D h-BCN atomic layers with a full range of compositions by ion beam sputtering deposition under a mixed Ar/CH4 atmosphere. The h-BCN layers have been thoroughly characterized by various techniques, aiming at the determination of their structure evolution and properties. We find that homogeneous h-BCN layers consisting of graphene and h-BN nanodomains can be obtained at an appropriate C content, whereas too high or too low C contents result in the segregation of large-sized graphene or h-BN islands. Furthermore, the band gap of h-BCN layers slightly decreases with the increasing C content, while their electric properties can be tuned from insulating to highly conducting. This work provides a novel approach for synthesizing 2D h-BCN atomic layers and paves the way for the development of h-BCN-based devices.

Two-dimensional (2D) hexagonal boron nitride (h-BN) is considered as an ideal dielectric layer or substrate for other 2D heterostructure electronic devices. However, reported 2D h-BN films consist mostly of small sized and randomly oriented h-BN domains, resulting in a high density of grain boundaries during coalescence. Here, we report the growth of unidirectionally aligned h-BN domains in a large area on the Ni(111) epitaxial thin film on MgO(111) substrate by ion beam sputtering deposition. It is found that the in-plane orientation of the underlying Ni thin film, which can be controlled by its deposition temperature, plays a key role in the h-BN domain alignment. Furthermore, density functional theory calculations are performed to determine the favorable configuration of the triangular shaped h-BN domains on Ni(111). This work provides a promising approach to prepare unidirectionally aligned h-BN domains in a large area, and thus it is possible to achieve wafer-scale single crystal h-BN by stitching th...

The American College of Medical Genetics and Genomics, and the Association for Molecular Pathology (ACMG/AMP) have proposed a set of evidence-based guidelines to support sequence variant interpretation. The ClinGen hearing loss expert panel (HL-EP) introduced further specifications into the ACMG/AMP framework for genetic hearing loss. This study developed a tool named VIP-HL, aiming to semi-automate the HL ACMG/AMP rules. VIP-HL aggregates information from external databases to automate 13 out of 24 ACMG/AMP rules specified by HL-EP, namely PVS1, PS1, PM1, PM2, PM4, PM5, PP3, BA1, BS1, BS2, BP3, BP4, and BP7. We benchmarked VIP-HL using 50 variants where 83 rules were activated by the ClinGen HL-EP. VIP-HL concordantly activated 96% (80/83) rules, significantly higher than that of by InterVar (47%; 39/83). Of 4948 ClinVar star 2+ variants from 142 deafness-related genes, VIP-HL achieved an overall variant interpretation concordance in 88.0% (4353/4948). VIP-HL is an integrated online tool for reliable automated variant classification in hearing loss genes. It assists curators in variant interpretation and provides a platform for users to share classifications with each other. VIP-HL is available with a user-friendly web interface at http://hearing.genetics.bgi.com/.

Hafnium disulfide (HfS2) has attracted significant interest because of the predicted excellent electronic properties superior to group VIB transition metal dichalcogenides. On the other hand, atomically thin hexagonal boron nitride (h-BN) is an ideal dielectric substrate for optoelectronic applications of other 2D materials. Here, for the first time, we report the direct growth of high-quality atomic layered HfS2 on few-layer h-BN transferred on SiO2/Si substrates by chemical vapor deposition. It was found that the HfS2 layers are selectively grown on h-BN rather than on SiO2/Si. Density functional theory calculations are performed to help understand the mechanism of selective growth of HfS2. Furthermore, the photodetectors based on the HfS2/h-BN heterostructures exhibit excellent visible-light sensing performance, such as a high on/off ratio of more than 105, an ultrafast response rate of about 200 μs, a high responsivity of 26.5 mA W–1, and a competitive detectivity exceeding 3 × 1011 Jones, superior to...

Hybrid organic-inorganic perovskites have attracted intensive interest as active materials for high-performance photodetectors. However, studies on the electron transport layer (ETL) and its influence on the response time of photodetectors remain limited. Herein, we compare the performances of perovskite photodetectors with TiO2 and SnO2 ETLs, especially on the response time. Both photodetectors exhibit a high on/off current ratio of 105, a large detectivity around 1012 Jones, and a linear dynamic range over 80 dB. The SnO2-based perovskite photodiodes show ultrahigh response rates of 3 and 6 μs for the rise and decay times, respectively. However, photodetectors with TiO2 ETLs have low responsivity and long response time at low driving voltage, which is attributed to the electron extraction barrier at the TiO2/perovskite interface and the charge traps in the TiO2 layer. Furthermore, the dark current of SnO2-based perovskite photodiodes is effectively suppressed by inserting a poly(vinylpyrrolidone) interlayer, and then the on/off current ratio increases to 1.2 × 106, corresponding to an improvement of 1 order of magnitude. Such low-cost, solution-processable perovskite photodetectors with high performance show promising potential for future optoelectronic applications.

Hexagonal boron nitride (h-BN), an isomorph of graphene, has attracted great attention owing to its potential applications as an ultra-flat substrate or gate dielectric layer in novel graphene-based devices. Besides, h-BN appears to be a promising material for deep ultraviolet (DUV) optoelectronic applications because of its extraordinary physical properties, such as wide band gap and high absorption coefficient. In this work, two-dimensional h-BN with controllable layers was synthesized on Cu foils by ion beam sputtering deposition, and DUV photodetectors were fabricated from the transferred h-BN layers on SiO2/Si substrates. The h-BN layers synthesized at the higher substrate temperature possess a lower density of domain boundaries and higher crystalline quality, and the photodetectors based on a 3 nm h-BN layer exhibited high performance with an on/off ratio of >103 under DUV light illumination at 212 nm and a cutoff wavelength at around 225 nm. This work demonstrates that two-dimensional h-BN layers are promising for the construction of high-performance solar-blind photodetectors.

Monoclinic β phase Ga2O3 has been considered as a promising candidate for next generation radio frequency and high-power devices because of its ultrawide bandgap and high breakdown field. The development of epitaxial growth techniques and the synthesis of high quality β-Ga2O3 thin films are crucial for the device applications. In this work, the heteroepitaxial β-Ga2O3 thin films were grown on sapphire (0001) substrates by low pressure chemical vapor deposition. The influence of growth parameters such as the source/substrate temperatures, the oxygen/Ar gas flow rates, and the surface morphology of substrate on the resultant crystallinity and surface roughness of the β-Ga2O3 films were investigated. The β-Ga2O3 heteroepitaxial layer on sapphire exhibits an RMS roughness of 1.82 nm, an XRD rocking curve of 1.18°, and a growth rate of 0.72 μm/h. The β-Ga2O3 film grown on the buffer layer exhibit a smoother surface, whereas the chemical etching and annealing lead to an improved crystallinity and a rough surface. However, there is a trade-off between the crystallization and the surface roughness.

Ferroelectric field-effect transistor has long been considered as a promising nonvolatile memory technology, but its application is limited by the poor scalability. Here we show that this problem can be solved by epitaxially integrating tetragonal BiFeO 3 , a stress-induced metastable phase which exhibits remarkably low dielectric permittivity and high coercive field, on the silicon platform. Tetragonal BiFeO 3 was stabilized on (001)-oriented silicon by using Bi 2 SiO 5 , which is chemically and structurally compatible with both silicon and tetragonal BiFeO 3 , as the buffer layer. Unlike the commonly observed M C structure, the obtained BiFeO 3 layer exhibits a true tetragonal symmetry. An unprecedented high memory window of 6.5 V was observed for the Au/BiFeO 3 /Bi 2 SiO 5 /Si capacitor with BiFeO 3 thickness of 135 nm. The epitaxial integration of tetragonal BiFeO 3 with silicon may pave a possible avenue for nanosized, power-efficient ferroelectric nonvolatile memories.

Recent studies have indicated that long non-coding RNAs (lncRNAs) and mRNA function as competing endogenous RNAs (ceRNAs) that compete to bind to shared microRNA (miRNA) recognition elements (MREs) to perform specific biological functions during tumorigenesis. The tumor suppressor p53 is a master regulator of cancer-related biological processes by acting as a transcription factor to regulate target genes including miRNA and lncRNA. However, the mechanism in human hepatocellular carcinoma and whether p53-mediated RNA targets could form ceRNA network remain unclear. Here, we identified a series of differential expressed miRNAs, lncRNA and mRNA which were potentially regulated by p53 using RNA sequencing in HepG2. Genomic characteristics comparative analysis showed significant differences between mRNAs and lncRNAs. By integrating experimentally confirmed Ago2 and p53 binding sites, we constructed a highly reliable p53-mediated ceRNA network using hypergeometric test. The KEGG pathway enrichment analysis showed that the ceRNA network highly enriched in the cancer or p53-associated signaling pathways. Finally, using betweenness centrality analysis, we identified five master miRNAs (hsa-miR-3620-5p, hsa-miR-3613-3p, hsa-miR-6881-3p, hsa-miR-6087 and hsa-miR-18a-3p) that regulated most of the target RNAs, suggesting these miRNAs play central roles in the whole p53-mediated ceRNAs network. Taken together, our results provide a new regulatory mechanism of p53 networks for future studies in cancer therapeutics.

All-inorganic perovskites, such as CsPbX3 (X = Cl, Br, I), have recently emerged as highly promising optoelectronic materials due to their excellent physical properties, especially their higher thermal stability. However, the performance of a CsPbX3-based photodetector is worse than its counterparts based on organic–inorganic hybrid perovskites. In this work, we demonstrate flexible high performance photodetectors based on the CsPbBr3/ZnO heterostructure using solution-processesing. Owing to the interfacial charge transfer from perovskite to ZnO, the photocurrent of devices was enhanced by more than one order of magnitude after the introduction of a ZnO layer. The CsPbBr3/ZnO heterostructure photodetectors exhibited high sensitivity with an on/off ratio of >104 under 450 nm light illumination and a high photoresponsivity of 4.25 A W−1. Furthermore, CsPbBr3/ZnO photodetectors with excellent stability and outstanding flexibility were also demonstrated. This work demonstrates that CsPbBr3/ZnO heterostructures are promising for the construction of high-performance photodetectors and other optoelectronic devices.

Graphene-on-silicon (Gr/Si) Schottky junction solar cells have recently attracted considerable interest as promising candidates for low-cost photovoltaic applications. However, the efficiency of Gr/Si cells is still much lower than that of crystalline Si solar cells, which is mainly attributed to the interface recombination of carriers due to the low Gr/Si Schottky barrier. Herein, a few-layer hexagonal boron nitride (h-BN) is introduced to engineer the Gr/Si interface for improving device performance. The h-BN can act as an effective electron-blocking/hole-transporting layer due to its unique properties and appropriate band alignment with Si, and thus the interface recombination was suppressed and the open circuit voltage was remarkably increased. On the other hand, the series resistance of solar cells decreases due to an improving conductivity of graphene on h-BN, leading to an increased short circuit current density. Furthermore, the interface defects and contamination arising from the layer-by-layer transfer process can be eliminated by using a directly grown Gr/h-BN heterostructure. As a result, a maximum efficiency of 10.93% was achieved by combining h-BN interlayer and co-doping of graphene with Au nanoparticles and HNO 3 , which shows the great potential of the novel Gr/h-BN/Si solar cells.

The mixed-cation lead mixed-halide perovskites can combine the advantages of the constituents while avoiding their drawbacks, and they have been widely explored in solar cells. However, there are only few research studies on the mixed-cation lead mixed-halide perovskites for photodetectors. In this work, we fabricate photodetectors based on FA(1-x)CsxPb(BryI(1-y))3 perovskite and reveal the effect of the chemical composition on the crystal phase stability and device performance of mixed-cation mixed-halide perovskite photodetectors. The FA0.7Cs0.3Pb(I0.8Br0.2)3 photodetectors exhibit high specific detectivity, high responsivity, and excellent stability in ambient conditions. Especially, the flexible perovskite photodetectors fabricated on poly(ethylene terephthalate) substrates exhibit extremely high specific detectivity of 2.8 × 1013 Jones, which is the highest value to date for flexible perovskite photodetectors, as well as excellent stability and outstanding flexibility. These results indicate that mixed-cation mixed-halide perovskites are promising to be applied in high-performance photodetectors and other flexible optoelectronic devices.

Boron nitride occurs in several crystalline phases, among which cubic boron nitride (c-BN) and hexagonal boron nitride (h-BN) are two of the most interesting wide bandgap materials from both scientific and practical viewpoints. They have been extensively investigated over many years. Due to their wide bandgap, good thermal conductivity, low dielectric constant, and high breakdown field, c-BN and h-BN are promising candidates for optoelectronic devices operating in the deep-ultraviolet range and for high-temperature and high-power electronic devices operating in harsh environments. This chapter first reviews the current status of the synthesis, properties, and characterizations of c-BN thin films, and then analyzes the growth features and proposed mechanisms of c-BN films. Next, some important progress, including stress relief of thick c-BN films and the epitaxial growth of c-BN films, is described. In recent theoretical and experimental research, several dopants, including Be, Mg, Zn, S, C, and Si, have been incorporated into c-BN thin films during deposition or by post ion implantation, resulting in both n- and p-type conduction. The following section of this chapter critically and comprehensively reviews the current status of the doping and electrical properties of c-BN films. Furthermore, the layered structure of h-BN allows the preparation of ultrathin nanosheets with very smooth surfaces and low defect density, which proved to be useful as supporting substrates and gate dielectric layers in two-dimensional (2D) nanoscale electronics. Apart from h-BN thin films, recent progress in properties, synthesis, and emerging applications of 2D h-BN is also reviewed in the last section.

Enhancers can act as cis-regulatory elements to control transcriptional regulation by recruiting DNA-binding transcription factors (TFs) in a tissue-specific manner. Recent studies show that enhancers regulate not only protein-coding genes but also microRNAs (miRNAs), and mutations within the TF binding sites (TFBSs) located on enhancers will cause a variety of diseases such as cancer. However, a comprehensive resource to integrate these regulation elements for revealing transcriptional regulations in the context of enhancers is not currently available. Here, we introduce EnhancerDB, a web-accessible database to provide a resource to browse and search regulatory relationships identified in this study, including 131 054 581 TF–enhancer, 17 059 enhancer–miRNAs, 318 993 enhancer–genes, 4 639 558 TF–miRNAs, 1 059 695 TF–genes, 11 439 394 enhancer–single-nucleotide polymorphisms (SNPs) and 23 334 genes associated with expression quantitative trait loci (eQTL) SNP and expression profile of TF/gene/miRNA across multiple human tissues/cell lines. We also developed a tool that further allows users to define tissue-specific enhancers by setting the threshold score of tissue specificity of enhancers. In addition, links to external resources are also available at EnhancerDB.

Featuring an absence of dangling bonds, large band gap, low dielectric constant, and excellent chemical inertness, atomically thin hexagonal boron nitride (h-BN) is considered an ideal candidate for integration with graphene and other 2D materials. During the past years, great efforts have been devoted to the research of h-BN-based heterostructures, from fundamental study to practical applications. In this review we summarize the recent progress in the synthesis, novel properties, and potential applications of h-BN-based heterostructures, especially the synthesis technique. Firstly, various approaches to the preparation of both in-plane and vertically stacked h-BN-based heterostructures are introduced in detail, including top-down strategies associated with exfoliation transfer processes and bottom-up strategies such as chemical vapor deposition (CVD)-based growth. Secondly, we discuss some novel properties arising in these heterostructures. Several promising applications in electronic and optoelectronic devices are also reviewed. Finally, we discuss the main challenges and possible research directions in this field.

Alloying transition metal dichalcogenides (TMDs) with different compositions is demonstrated as an effective way to acquire 2D semiconductors with widely tunable bandgaps. Herein, for the first time, the large-area synthesis of layered HfS

Perovskite light-emitting diodes (LEDs) are attracting great attention due to their efficient and narrow emission. Quasi-two-dimensional perovskites with Ruddlesden–Popper-type layered structures can enlarge exciton binding energy and confine charge carriers and are considered good candidate materials for efficient LEDs. However, these materials usually contain a mixture of phases and the phase impurity could cause low emission efficiency. In addition, converting three-dimensional into quasi-two-dimensional perovskite introduces more defects on the surface or at the grain boundaries due to the reduction of crystal sizes. Both factors limit the emission efficiency of LEDs. Here, firstly, through composition and phase engineering, optimal quasi-two-dimensional perovskites are selected. Secondly, surface passivation is carried out by coating organic small molecule trioctylphosphine oxide on the perovskite thin film surface. Accordingly, green LEDs based on quasi-two-dimensional perovskite reach a current efficiency of 62.4 cd A−1 and external quantum efficiency of 14.36%., Solution-processable halide perovskites have high luminous efficiency and excellent chemical tunability, making them ideal candidates for light-emitting diodes. Here Yang et al. achieve high external quantum efficiency of 14% in the devices by fine-tuning the phase and passivating the surface defects.

Hybrid organic-inorganic perovskites have attracted intensive interest as active materials for high-performance photodetectors. However, studies on the electron transport layer (ETL) and its influence on the response time of photodetectors remain limited. Herein, we compare the performances of perovskite photodetectors with TiO

We have quantitatively characterized the phase separation of poly(3-hexylthiophene) (P3HT):C61-butyric acid methyl ester (PCBM) blend films and studied the effect of phase separation of photoactive layer on the performance of polymer solar cells. A mixed solvent of dichlorobenzene and chlorobenzene was adopted to prepare the P3HT:PCBM blend films, and a series of blend films with different morphologies were obtained by adjusting both the volume ratio of dichlorobenzene to chlorobenzene and the solvent annealing time. The surface morphology and phase distribution were measured by atomic force microscopy (AFM). The interface length between the domains of donor and acceptor, which is extracted from the AFM phase image of blend film, was used to quantitatively characterize the phase separation of photoactive layer. It was found that the short-circuit current density ( J SC ) of bulk heterojunction solar cells is proportional to the interfacial area of two phases, while it has a negligible effect on the open-circuit voltage. These results indicate that the larger interfacial area of donor and acceptor phases is beneficial to the exciton dissociation and carrier transport resulting in a significant increase of J SC and power conversion efficiency.

Bulk heterojunction (BHJ) solar cells with a solution-processed ZnO electron transport layer (ETL) were fabricated, and the effects of surface modification of the ZnO ETL by H-plasma treatment on the device performance were systemically investigated. It was found that the open circuit voltage (VOC) of the BHJ solar cells was dramatically improved after H-plasma treatment, while the short-circuit current density (JSC) exhibited a consistent decrease with increasing H-plasma treatment time. Both Kelvin probe force microscopy and ultraviolet photoelectron spectroscopy measurements indicate that the improved VOC is attributed to the reduced work function of ZnO caused by H-plasma treatment, while photoluminescence spectra suggest that the inefficient exciton dissociation associated with the H-plasma treatment leads to a decrease in JSC with tH. After 2.5 min of H-plasma treatment, the power conversion efficiency (PCE) of the solar cells was increased from 3.03% to 3.84% with a high VOC of 0.670 V, corresponding to an improvement of 27%. This work provides a novel and efficient route to improving the VOC and thus the efficiency of BHJ solar cells.

Both high efficiency and good stability of organometal trihalide perovskite solar cells are of central importance for their practical application. Here we report the fabrication of highly efficient and stable planar heterojunction perovskite solar cells through a simple and low temperature solution process. By combining the slow growth of the perovskite film and the introduction of a ZnO interlayer, a maximum power conversion efficiency of 16.8% was achieved. More importantly, the devices showed excellent stability, which can maintain their almost original performance after storing in ambient air for two months. It has been found that the ZnO interlayer is critical in enhancing the efficiency and stability of the devices. Furthermore, the low temperature solution process and the planar device structure used in this work are well compatible with the large-area and flexible substrates.

Graphene/hexagonal boron nitride (h-BN) heterostructures have attracted a great deal of attention in recent years due to their unique and complementary properties for use in a wide range of potential applications. However, it still remains a challenge to synthesize large-area high quality samples by a scalable growth method. In this work, we present the synthesis of both in-plane and stacked graphene/h-BN heterostructures on Cu foils by sequentially depositing h-BN via ion beam sputtering deposition (IBSD) and graphene with chemical vapor deposition (CVD). Due to a significant difference in the growth rate of graphene on h-BN and Cu, the in-plane graphene/h-BN heterostructures were rapidly formed on h-BN domain/Cu substrates. The large-area vertically stacked graphene/h-BN heterostructures were obtained by using the continuous h-BN film as a substrate. Furthermore, the well-designed sub-bilayered h-BN substrates provide direct evidence that the monolayered h-BN on Cu exhibits higher catalytic activity than the bilayered h-BN on Cu. The growth method applied here may have great potential in the scalable preparation of large-area high-quality graphene/h-BN heterostructures.

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity (R2 = 0.9992) within 10–2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations