In Situ Photogenerated Radicals of Hydroxyl Substituted Pyrene-Based Triphenylamines with Enhanced Transport and Free Doping/Post-Oxidation for Efficient Perovskite Solar Cells.

The high-performance hole transporting material (HTM) is one of the most important components for the perovskite solar cells (PSCs) in promoting power conversion efficiency (PCE). However, the low conductivity of HTMs and their additional requirements for doping and post-oxidation greatly limits the device performance. In this work, three novel pyrene-based derivatives containing methoxy-substituted triphenylamines units (PyTPA, PyTPA-OH and PyTPA-2OH) are designed and synthesized, where different numbers of hydroxyl groups are connected at the 2- or 2,7-positions of the pyrene core. These hydroxyl groups at the 2- or 2,7-positions of pyrene play a significantly role to enhance the intermolecular interactions that are able to generate in situ radicals with the assistance of visible light irradiation, resulting in enhanced hole transferring ability, as well as an enhanced conductivity and suppressed recombination. These pyrene-core based HTMs exhibit excellent performance in PSCs, which possess a higher PCE than those control devices using the traditional spiro-OMeTAD as the HTM. The best performance can be found in the devices with PyTPA-2OH. It has an average PCE of 23.44% (PCEmax = 23.50%), which is the highest PCE among the reported PSCs with the pyrene-core based HTMs up to date. This research offers a novel avenue to design a dopant-free HTM by the combination of the pyrene core, methoxy triphenylamines, and hydroxy groups.

Highly Stable Perovskite Solar Cells Based on the Efficient Interaction between Pb2+ and Cyano Groups of 4-Aminophthalonitrile.

Defects present on the top surface of perovskite films have a pronounced detrimental impact on the photovoltaic performance and stability of perovskite solar cells (PSCs). Consequently, the development of effective defect passivation strategies has become key in enhancing both the power conversion efficiency (PCE) and stability of PSCs. In this study, a small molecule material, 4-Aminophthalonitrile (4-APN), was introduced as a means to mitigate surface defects within perovskite films. Obviously, 4-APN effectively passivates the defects at grain boundaries by combining cyano groups (-C≡N) with Pb2+ , significantly reducing the density of defect states, inhibiting non-radiative recombination at the interface, and promoting the charge transfer efficiency from the perovskite layer to the hole transport layer. The 4-APN modification led to a significant upswing in the PCE, while concurrently bolstering the overall device stability. Importantly, the devices on 4-APN as passivation additive exhibited negligible performance degradation aging for 1200 h.

Highly efficient blue and warm white organic light-emitting diodes with a simplified structure.

Two blue fluorescent emitters were utilized to construct simplified organic light-emitting diodes (OLEDs) and the remarkable difference in device performance was carefully illustrated. A maximum current efficiency of 4.84 cd A(-1) (corresponding to a quantum efficiency of 4.29%) with a Commission Internationale de l'Eclairage (CIE) coordinate of (0.144, 0.127) was achieved by using N,N-diphenyl-4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1, 1':4', 1″-terphenyl]-4-amine (BBPI) as a non-doped emission layer of the simplified blue OLEDs without carrier-transport layers. In addition, simplified fluorescent/phosphorescent (F/P) hybrid warm white OLEDs without carrier-transport layers were fabricated by utilizing BBPI as (1) the blue emitter and (2) the host of a complementary yellow phosphorescent emitter (PO-01). A maximum current efficiency of 36.8 cd A(-1) and a maximum power efficiency of 38.6 lm W(-1) were achieved as a result of efficient energy transfer from the host to the guest and good triplet exciton confinement on the phosphorescent molecules. The blue and white OLEDs are among the most efficient simplified fluorescent blue and F/P hybrid white devices, and their performance is even comparable to that of most previously reported complicated multi-layer devices with carrier-transport layers.

MAPKAPK5-AS1 drives the progression of hepatocellular carcinoma via regulating miR-429/ZEB1 axis.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignancy. Long non-coding RNAs (lncRNAs) partake in the progression of HCC. However, the role of lncRNA MAPKAPK5-AS1 in the development of HCC has not been fully clarified. METHODS: RNA sequencing data and quantitative real-time polymerase chain reaction (qRT-PCR) were adopted to analyze MAPKAPK5-AS1, miR-429 and ZEB1 mRNA expressions in HCC tissues and cell lines. Western blot was used to detect ZEB1, E-cadherin and N-cadherin protein expressions. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Transwell and flow cytometry assays were adopted to analyze the effects of MAPKAPK5-AS1 on cell proliferation, migration, invasion and apoptosis. Besides, luciferase reporter assay was used to detect the targeting relationship between miR-429 and MAPKAPK5-AS1 or ZEB1 3'UTR. The xenograft tumor mouse models were used to explore the effect of MAPKAPK5-AS1 on lung metastasis of HCC cells. RESULTS: MAPKAPK5-AS1 and ZEB1 expressions were up-regulated in HCC tissues, and miR-429 expression is down-regulated in HCC tissues. MAPKAPK5-AS1 knockdown could significantly impede HCC cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT), as well as promote cell apoptosis. MAPKAPK5-AS1 overexpression could enhance L02 cell proliferation, migration, invasion and EMT, and inhibit cell apoptosis. MiR-429 was validated to be the target of MAPKAPK5-AS1, and miR-429 inhibitors could partially offset the effects of knocking down MAPKAPK5-AS1 on HCC cells. MAPKAPK5-AS1 could positively regulate ZEB1 expression through repressing miR-429. Moreover, fewer lung metastatic nodules were observed in the lung tissues of nude mice when the MAPKAPK5-AS1 was knocked down in HCC cells. CONCLUSION: MAPKAPK5-AS1 can adsorb miR-429 to promote ZEB1 expression to participate in the development of HCC.

Transparent, smooth, and sustainable cellulose-derived conductive film applied for the flexible electronic device.

A high-performance flexible conductive substrate is one of the key components for developing promising wearable devices. Concerning this, a sustainable, flexible, transparent, and conductive cellulose/ZnO/AZO (CZA) film was developed in this study. The cellulose was used as the transparent substrate. The added AZO was as the conductive layer and ZnO functioned as an interface buffer layer. Results showed that the interface buffer layer of ZnO effectively alleviated the intrinsic incompatibility of organic cellulose and inorganic AZO, resulting in the improvement of the performance of CZA film. In compared with the controlled cellulose/AZO (CA) film with 365 Ω/sq sheet resistance and 87% transmittance, this CZA film featured a low conductive sheet resistance of 115 Ω/sq and high transmittance of 89%, as well as low roughness of 1.85 nm Moreover, the existence of conducive ZnO buffer layer enabled the conductivity of CZA film to be stable under the bending treatment. Herein, a flexible electronic device was successfully prepared with the biomass materials, which would be available by a roll-to-roll production process.

Novel Mn4+ doped red phosphors composed of MgAl2O4 and CaAl12O19 phases for light-emitting diodes.

Red emitters based on CaAl12O19:Mn4+ have been attracting extensive attention due to their advantages of being rare-earth-free and chemically stable. However, their relatively low luminescence efficiencies will seriously hinder their application in light-emitting diodes (LEDs). In this regard, the promising red phosphors of CaAl12O19:Mn4+ were synthesized with enhanced luminous efficiency by introducing the coexisting phase of MgAl2O4. Importantly, an approximately 5 times enhancement of integrated intensity in the emission spectrum was observed for the phosphor with the coexisting phase compared to that with a single phase. Their crystal structures, morphologies and photoluminescence properties and the mechanism of improved luminescence were systematically investigated. Upon exciting them by using near-ultraviolet or blue LEDs, an efficient red emission was achieved with a maximum peak at ∼658 nm. In order to evaluate their potential application, a warm white LED and a plant growth LED were fabricated by using the prepared phosphors in combination with YAG:Ce3+ and InGaN-based blue chips.

Conductive Regenerated Cellulose Film and Its Electronic Devices - A Review.

Natural cellulose features the outstanding merits of biodegradability, large-volume production and worldwide availability, which has become a promising material for achieving a sustainable society. Based on a simple dissolution-regeneration process of natural cellulose, the flexible, transparent, and smooth regenerated cellulose film (RCF) can be easily manufactured. The RCF can become conductive by introducing the conductive materials, which has presented potential applications for high-performance electronic devices. Herein, we summarized the mainly non-derivative solvents for the preparation of the RCF as well as the conductive materials for manufacturing the conducive regenerated cellulose film (CRCF). In addition, the CRCF-based versatile electronic device were also introduced.

From Straw to Device Interface: Carboxymethyl-Cellulose-Based Modified Interlayer for Enhanced Power Conversion Efficiency of Organic Solar Cells.

Advanced interface materials made from petrochemical resources have been extensively investigated for organic solar cells (OSCs) over the past decades. These interface materials have demonstrated excellent performances in OSC devices. However, the limited resources, high-cost, and non-ecofriendly nature of petrochemical-based interface materials restrict their commercial applications. Here, a facile and effective approach to prepare cellulose and its derivatives as a cathode interface layer for OSCs with enhanced performance from rice straw of agroforestry residues is demonstrated. By employing this carboxymethyl cellulose sodium (CMC) into OSCs, a highly efficient inverted OSC is constructed, and a power conversion efficiency (PCE) of 12.01% is realized using poly[(2,6-(4,8-bis(5-(2-ethyl-hexyl)-thiophen-2-yl)-benzo[1,2-b:4,5-b'] dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c: 4',5'-c']dithiophene-4,8-dione): 3,9-bis(2-methylene-((3-(1, 1-dicyanomethylene)-6/7-methyl)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d: 2',3'-d']-s-indaceno[1,2-b: 5, 6-b']dithiophene as the active layer, which shows over 9.4% improvement in PCE compared to that of a device without the CMC layer (PCE = 10.98%), especially the enhancement in short-circuit current. The improved current densities and PCEs are attributed to the reduced work function, enhanced absorption, and improved interfacial contact by using CMC and ZnO as co-interface. This approach of fabricating interface materials from biorenewable sources for OSCs is simple, scalable, and cost-effective, representing a promising direction for the development of smart interface and green electronics.

Mussel-inspired cellulose-based adhesive with biocompatibility and strong mechanical strength via metal coordination.

Inspired by marine mussel, catechol-containing materials, such as adhesives, self-healing hydrogels, and antifouling coatings, have been developed with wide applications in chemical, biomedical, and electronics industries. Conventionally, petrochemicals or organic solvents are widely used for preparation and dissolution of adhesives, which makes the adhesives are not eco-friendly and biocompatible. To develop environmentally friendly and biocompatible adhesives with desired properties, here we report catechol-containing cellulose-based tissue adhesives, synthesized by incorporating catechol groups onto cellulose. The structures of the adhesives with different catechol contents were analyzed by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR) spectroscopy. The adhesion strengths were examined using porcine skin by lap shear tensile tests. The adhesion strength of the as-prepared adhesive with catechol content of 16.5 mol% was 20.0 kPa. Fe3+ was used as crosslinker to enhance the adhesion strength and accelerate the solidification of adhesives. Through the Fe3+-catechol coordination, the adhesion strength of adhesive was increased to 88.0 kPa, showing strong mechanical strength compared to the fibrin adhesive. NIH 3T3 cells test demonstrates that the adhesive is favorable for cell attachment and proliferation, possessing excellent biocompatibility. The catechol-containing cellulose-based adhesive has promising application in bioengineering field.

Cellulose transparent conductive film and its feasible use in perovskite solar cells.

A transparent conductive Ag nanowire (AgNW)-regenerated cellulose film (RCF) was prepared and has been proposed to be used as an anode for perovskite solar cells. The HNO3 treatment was used for solving the dilemma between optical transparency and conductivity caused by the AgNW introduction; in addition, the bonding strength between AgNWs and cellulose film was enhanced substantially via HNO3 treatment. Accordingly, the AgNW-RCF with a AgNW size of 15 µm × 85 nm and density of 0.36 g m-2 shows impressive conductivity and transparency, with a sheet resistance of 29 Ω â–¡-1 and a transmittance of 80% at a wavelength of 550 nm. Perovskite solar cells incorporating such AgNW-RCF anodes exhibited a cell performance with a V oc of 1.02 V, J sc of 9.58 mA cm-2, FF of 45.8% and PCE of 4.49%.

Cellulase pretreatment for enhancing cold caustic extraction-based separation of hemicelluloses and cellulose from cellulosic fibers.

The effective separations of cellulose and hemicelluloses from cellulosic fibers are the prerequisite for creating high-value to the abundant and green cellulose materials. In this study, the process concept of cellulase pretreatment, followed by a cold caustic extraction (CCE) was investigated for a softwood sulfite pulp. The results showed that the cellulase pretreatment led to favorable fiber morphological changes, including the increases of the specific surface area (SSA), pore volume and diameter, and the water retention value (WVR). These changes can induce more pronounced fiber swelling in the subsequent CCE process so that the hemicelluloses removal is enhanced. After the cellulase pretreatment (cellulase dosage of 1 mg/g) and CCE process, the cellulose purity was as high as 97.49%, while the hemicelluloses removal selectivity reached 76.42%.

Robust superhydrophobic and superoleophilic filter paper via atom transfer radical polymerization for oil/water separation.

Robust superhydrophobic and superoleophilic cellulose-g-PFOEMA filter paper membranes were fabricated via surface grafting of poly(perfluorooctylethyl methacrylate) (PFOEMA) using atom transfer radical polymerization (ATRP). The surface chemical compositions, morphologies and wettability of cellulose-g-PFOEMA with different degree of graft ratio (DG) were investigated using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and contact angle (CA) measurement. IR and XPS showed that PFOEMA were introduced into surface of filter paper. The superhydrophobicity of filter paper increased with amount of PFOEMA grafted. When DG of grafted PFOEMA was higher than 11.2%, the superhydrophobicity reached a steady state and the measured water contact angle was about 157°. The PFOEMA-grafted filter paper exhibited excellent chemical resistance toward a wide range of pH solution from 1 to 12. Cellulose-g-PFOEMA is convenient for oil/water separation with efficiency higher than 95%. The excellent reusability and stability make cellulose-g-PFOEMA filter paper membrane a promising candidate in the applications of oil spillage cleanup and the separation of oil/water mixture.

Self-Healing Cellulose Nanocrystals-Containing Gels via Reshuffling of Thiuram Disulfide Bonds.

Self-healing gels based on reshuffling disulfide bonds have attracted great attention due to their ability to restore structure and mechanical properties after damage. In this work, self-healing gels with different cellulose nanocrystals (CNC) contents were prepared by embedding the thiuram disulfide bonds into gels via polyaddition. By the reshuffling of thiuram disulfide bonds, the CNC-containing gels repair the crack and recover mechanical properties rapidly under visible light in air. The thiuram disulfide-functionalized gels with a CNC content of 2.2% are highly stretchable and can be stretched approximately 42.6 times of their original length. Our results provide useful approaches for the preparation of dynamic CNC-containing gels with implications in many related engineering applications.

MoS2 Quantum Dots with a Tunable Work Function for High-Performance Organic Solar Cells.

An efficient hole extraction layer (HEL) is critical to achieve high-performance organic solar cells (OSCs). In this study, we developed a pinhole-free and efficient HEL based on MoS2 quantum dots (QDs) combined with UV-ozone (UVO) treatment. The optophysical properties and morphology of MoS2 QDs and their photovoltaic performance are investigated. The results showed that MoS2 QDs can form homogeneous films and can be applied as an interfacial layer not only for donors with shallow highest occupied molecular orbital (HOMO) but also for those with deep HOMO energy levels after UVO treatment (O-MoS2 QDs). The solar cells based on O-MoS2 QDs yield a power conversion efficiency (PCE) of 8.66%, which is 71% and 12% higher than those of the OSCs with pristine MoS2 QD and O-MoS2 nanosheets, respectively, and the highest PCEs for OSCs containing MoS2 materials. Furthermore, the stability of solar cells based on MoS2 QDs is greatly improved in comparison with state-of-the-art PEDOT:PSS. These results demonstrate the great potential of O-MoS2 QDs as an efficient HEL for high-performance OSCs.

Novel "hot exciton" blue fluorophores for high performance fluorescent/phosphorescent hybrid white organic light-emitting diodes with superhigh phosphorescent dopant concentration and improved efficiency roll-off.

Two blue fluorophores with excellent hybridized local and charge-transfer (HLCT) and "hot exciton" properties were developed as the blue emitter and the host for orange-red phosphor to achieve highly efficient fluorescent/phosphorescent (F/P) hybrid white organic light-emitting diodes (WOLEDs) in a single-emissive-layer single-dopant (SEML-SD) architecture even at a high concentration of phosphorescent dopant. In the devices, part of the triplet excitons of the blue fluorophores can be utilized to realize reverse intersystem crossing from the triplet excited states to the singlet excited states for blue emission, and the diffusion volume range of the triplet excitons is reduced significantly. When the phosphorescent dopant concentration is up to 1.0 wt %, which is ten times higher than the traditional single-EML-SD F/P hybrid WOLEDs, highly efficient white emission was still achieved with maximum total external quantum efficiency (EQE) of 23.8%, current efficiency (CE) of 56.1 cd A(-1), and power efficiency (PE) of 62.9 lm W(1-). The results will supply a novel method for obtaining high efficiency F/P hybrid WOLEDs in a SEML-SD architecture with easily controllable doping concentration.

Synthesis, strong two-photon absorption, and optical limiting properties of novel C(70)/C(60) derivatives containing various carbazole units.

An approach was demonstrated toward the design and synthesis of a series of novel C(70) and C(60) derivatives for large two-photon absorption (TPA). The molecular structures of fullerene derivatives were confirmed by MALDI-MS, (1)H NMR, and FT-IR. With femtosecond open-aperture Z-scans and frequency-degenerate pump-probe measurements at 780 nm, the TPA cross sections of up to 3.47 x 10(-46), 1.64 x 10(-46), 1.1 x 10(-46), and 7.82 x 10(-47) cm(4) s photon(-1) molecule(-1) were determined for C(70)-TCTA, C(60)-TCTA, C(70)-BCzMB, and C(70)-MQEtCz in toluene with concentrations of 10(-4) M, respectively. The normalized light transmittances of solutions of these molecules were attenuated to the range between 33% and 50% for C(70)-TCTA, C(60)-TCTA, C(60)-BCzMB, and C(70)-MQEtCz as the input irradiance was increased to about 150 GW/cm(2), showing that they are effective optical limiters. Both intensity-dependent Z-scans and pump-probe experiments confirmed that the reduction in the light transmittance results mainly from the TPA process. In addition, the molecule concentration dependence of the TPA cross sections was also investigated. It was found that the TPA cross sections are extremely sensitive to the concentration with the greatest TPA cross-section of 1.0 x 10(-45) cm(4) s photon(-1) molecule(-1) for C(70)-TCTA measured in the low concentration regime ( approximately 10(-5) M).

8-Hydroxyquinoline derivatives induce the proliferation of rat mesenchymal stem cells (rMSCs).

A series of 8-hydroxyquinoline derivatives with different substituted groups at 2- or 5-position have been synthesized and characterized. Their effects on the proliferation of the rat marrow-derived mesenchymal stem cells (rMSCs) have been evaluated by MTT assay and flow cytometry. We also analyzed the ability of these compounds to regulate the proliferation of rMSCs and the relationship with the structures of 8-hydroxyquinoline. Compounds 8-11, in which, the vinyl-substituents are on the 2-position of 8-hydroxyquinoline, appear to be able to induce the proliferation of rMSCs. These results show that compounds 8-11 provide a kind of new substances for regulating the proliferation of rMSCs.