Tin-Lead Perovskite Solar Cells with Preferred Crystal Orientation by Buried Interface Approach.

Mixed tin-lead perovskite solar cells (PSCs) have garnered much attention for their ideal bandgap and high environmental research value. However, poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT: PSS), widely used as a hole transport layer (HTL) for Sn-Pb PSCs, results in unsatisfactory power conversion efficiency (PCE) and long-term stability of PSCs due to its acidity and moisture absorption. A synergistic strategy by incorporating histidine (HIS) into the PEDOT: PSS HTL is applied to simultaneously regulate the nucleation and crystallization of perovskite (PVK). HIS neutralizes the acidity of PEDOT: PSS and enhances conductivity. Especially, the coordination of the C═N and -COO- functional groups in the HIS molecule with Sn2+ and Pb2+ induces vertical growth of PVK film, resulting in the release of residual surface stress. Additionally, this strategy also optimizes the energy level alignment between the perovskite layer and the HTL, which improves charge extraction and transport. With these cooperative effects, the PCE of Sn-Pb PSCs reaches 21.46% (1 sun, AM1.5), maintaining excellent stability under a nitrogen atmosphere. Hence, the buried interface approach exhibits the potential for achieving high-performance and stable Sn-Pb PSCs.

Ternary-Metal Sn-Pb-Zn Perovskite to Reconstruct Top Surface for Efficient and Stable Less-Pb Perovskite Solar Cells.

Though Sn-Pb alloyed perovskite solar cells (PSCs) achieved great progress, there is a dilemma to further increase Sn for less-Pb requirement. High Sn ratio (>70%) perovskite exhibits nonstoichiometric Sn:Pb:I at film surface to aggravate Sn2+ oxidation and interface energy mismatch. Here, ternary metal alloyed (FASnI3 )0.7 (MAPb1- x Znx I3 )0.3 (x = 0-3%) is constructed for Pb% < 30% perovskite. Zn with smaller ionic size and stronger ionic interaction than Sn/Pb assists forming high-quality perovskite film with ZnI6 4- enriched at surface to balance Sn:Pb:I ratio. Differing from uniform bulk doping, surface-rich Zn with lower lying orbits pushes down the energy band of perovskite and adjusts the interface energy for efficient charge transfer. The alloyed PSC realizes efficiency of 19.4% at AM1.5 (one of the highest values reported for Pb% < 30% PSCs). Moreover, stronger bonding of Zn─I and Sn─I contributes to better durability of ternary perovskite than binary perovskite. This work highlights a novel alloy method for efficient and stable less-Pb PSCs.

Urea additive improves the performance of low bandgap tin-lead perovskite solar cells.

Recently, narrow bandgap tin-lead mixed perovskite solar cells (PSCs) have become a research hotspot because they can be applied in tandem cells to break the Shockley-Queisser radiative limit of the single junction PSCs. However, the introduction of tin, on the one hand, makes the crystal quality of perovskite thin film worse, leading to the increase of film defects; on the other hand, the easy oxidation of divalent tin also leads to the increase of defect states, which seriously affects the photoelectric conversion efficiency of tin-lead cell devices. Good crystallization and low defect density of perovskite layer are very important to ensure good light absorption and photogenerated carrier generation and transport. Here, we adjust the crystallization of tin-lead perovskite films by a Lewis base-urea (CO(NH2)2), which significantly increases the grain size and improves the film morphology. At the same time, because of the Lewis base property of urea, the uncoordinated Pb2+and Sn2+defects of Lewis acids in the tin-lead films are effectively passivated, and the occurrence of non-radiative recombination in the films is reduced. Under the dual effects of improving crystallization and passivating defects, the photoelectric performance of tin-lead perovskite solar cell devices is significantly improved to 18.1% compared with the original device of 15.4%.

[Analysis and Improvement Suggestions on Change of Medical Devices Licensing Items].

Based on the statistics of 350 technical evaluations of changes in licensing items of class Ⅱ passive and active medical devices completed in Henan province from July 2017 to November 2018, this paper summarized and analysed the common problems and requirements listed in the correction notifications of the technical evaluation, and put forward relevant countermeasures or suggestions, with a view to further speeding up the evaluation and approval of medical devices.

Polymer Lewis Base for Improving the Charge Transfer in Tin-Lead Mixed Perovskite Solar Cells.

The poor film stability of Sn-Pb mixed perovskite film and the mismatched interface energy levels pose significant challenges in enhancing the efficiency of tin-lead (Sn-Pb) mixed perovskite solar cells. In this study, polyvinylpyrrolidone (PVP) is introduced into the PVK perovskite precursor solution, effectively enhancing the overall stability of the film. This improvement is achieved through the formation of robust coordination bonds between the carbonyl (C=O) in the pyrrole ring and the undercoordinated SnII and PbII, thereby facilitating the passivation of defects. Furthermore, the introduction of PVP inhibits the oxidation of tin (Sn), thereby enhancing the n-type characteristics of the perovskite film. This adjustment in the energy level of the PVK perovskite film proves instrumental in reducing interface energy loss, subsequently improving interface charge transfer and mitigating device recombination. Consequently, perovskite solar cells incorporating PVP achieve an outstanding champion power conversion efficiency (PCE) of 21.31%.

Reductive Sn2+ Compensator for Efficient and Stable Sn-Pb Mixed Perovskite Solar Cells.

Tin-lead (Sn-Pb) mixed perovskite with a narrow bandgap is an ideal candidate for single-junction solar cells approaching the Shockley-Queisser limit. However, due to the easy oxidation of Sn2+, the efficiency and stability of Sn-Pb mixed perovskite solar cells (PSCs) still lag far behind that of Pb-based solar cells. Herein, highly efficient and stable FA0.5MA0.5Pb0.5Sn0.5I0.47Br0.03 compositional PSCs are achieved by introducing an appropriate amount of multifunctional Tin (II) oxalate (SnC2O4). SnC2O4 with compensative Sn2+ and reductive oxalate group C2O4 2- effectively passivates the cation and anion defects simultaneously, thereby leading to more n-type perovskite films. Benefitting from the energy level alignment and the suppression of bulk nonradiative recombination, the Sn-Pb mixed perovskite solar cell treated with SnC2O4 achieves a power conversion efficiency of 21.43%. More importantly, chemically reductive C2O4 2- effectively suppresses the notorious oxidation of Sn2+, leading to significant enhancement in stability. Particularly, it dramatically improves light stability.

Efficient Air-Processed MA-Free Perovskite Solar Cells by SH-Based Silane Interface Modification.

Air-processed perovskite solar cells (PSCs) with high photoelectric conversion efficiency (PCE) can not only further reduce the production cost but also promote its industrialization. During the preparation of the PSCs in ambient air, the contact of the buried interface not only affects the crystallization of the perovskite film but also affects the interface carrier transport, which is directly related to the performance of the device. Here, we optimize the buried interface by introducing 3-mercaptopropyltrimethoxysilane (MPTMS, (CH3O)3Si(CH2)3SH) on the nickel oxide (NiOx) surface. The crystallization of the perovskite film is improved by enhancing surface hydrophobicity; besides, the SH-based functional group of MPTMS passivates the uncoordinated lead at the interface, which effectively reduces the defects at the bottom interface of perovskite and inhibits the nonradiative recombination at the interface. Moreover, the energy level between the NiOx layer and the perovskite layer is better matched. Based on multiple functions of MPTMS modification, the open circuit voltage of the device is obviously improved, and efficient air-processed methylamine-free (MA-free) PSCs are realized with PCE reaching 21.0%. The device still maintains the initial PCE of 85% after 1000 h aging in the glovebox. This work highlights interface modification in air-processed MA-free PSCs to promote the industrialization of PSCs.

Photo-assisted degradation of Rhodamine B by a heterogeneous Fenton-like process: performance and kinetics.

This study presents the degradation of rhodamine B (RhB) by photo Fenton-like (PF-like) process under visible light irradiation (λ > 380 nm) using cobalt phosphate microparticles (CoP-MPs). The effects of the initial concentration of RhB, pH value, CoP-MPs dosage, hydrogen peroxide (H2O2) concentration, and salts found in textile wastewater (such as NaNO3, Na2SO4, and NaCl) were investigated in detail. It was found that CoP-MPs can maintain high catalytic activity with wide pH values varying from 4 to 8. This indicated that the use of CoP-MPs overcame the low efficiency of Fenton-like reaction at neutral and even weakly alkaline pH. The PF-like degradation of RhB followed pseudo-first order kinetics in various conditions. Moreover, a comparison of experimental results showed that the PF-like system has good degradation ability for RhB and methyl blue (MB) solution, but is poor for methyl orange (MO) solution. The repeat experiments indicated that the chemical structures of CoP-MPs were stable. Furthermore, the Co2+ ions leaching to the solutions were measured by an inductively coupled plasma mass spectrometer (ICP-MS). Analysis of UV-vis spectra suggested that RhB was degraded by the formation of a series of N-de-ethylated intermediates followed by cleavage of the whole conjugate chromophore structure.HighlightsRhB can be effectively degraded in the PF-like process under visible light irradiation by CoP-MPs.The PF-like process can maintain high catalytic activity at neutral and even weakly alkaline pH.Degradation kinetics exhibited pseudo-first-order kinetics and were influenced by the key parameters.The variation in the UV-vis spectra of RhB was analyzed in detail to infer a possible degradation pathway.

Thermoreversible and tunable supramolecular hydrogels based on chitosan and metal cations.

A new thermoreversible and tunable hydrogel CS-M with high water content prepared by metal cation (M = Cu2+, Zn2+, Cd2+ and Ni2+) and chitosan (CS) was reported. The influence of metal cations on the thermosensitive gelation of CS-M systems were studied. All prepared CS-M systems were in the transparent and stable sol state and could become the gel state at gelation temperature (Tg). These systems after gelation could recover to its original sol state at low temperature. CS-Cu hydrogel was mainly investigated and characterized due to its large Tg scale (32-80 °C), appropriate pH range (4.0-4.6) and low Cu2+ concentration. The result showed that the Tg range was influenced and could be tuned by adjusting Cu2+ concentration and system pH within an appropriate range. The influence of anions (Cl-, NO3- and Ac-) in cupric salts in the CS-Cu system was also investigated. Scale application as heat insulation window was investigated outdoors. The different supramolecular interactions of the -NH2 group in chitosan at different temperatures were proposed to dominate the thermoreversible process of CS-Cu hydrogel.

Alkali Metal Cations Modulate the Energy Level of SnO2 via Micro-agglomerating and Anchoring for Perovskite Solar Cells.

N-type tin oxide (SnO2) films are commonly used as an electron transport layer (ETL) in perovskite solar cells (PSCs). However, SnO2 films are of poor quality due to facile agglomeration under a low-temperature preparation method. In addition, energy level mismatch between the SnO2 and perovskite (PVK) layer as well as interfacial charge recombination would cause open-circuit voltage loss. In this work, alkali metal oxalates (M-Oxalate, M = Li, Na, and K) are doped into the SnO2 precursor to solve these problems. First, it is found that the hydrolyzed alkali metal cations tend to change colloid size distribution of SnO2, in which Na-Oxalate with suitable basicity leads to most uniform colloid size distribution and high-quality SnO2-Na films. Second, the electron conductivity is enhanced by slightly agglomerated SnO2-Na, which facilitates the transmission of electrons. Third, alkali metal cations increase the conduction band level of SnO2 in the sequence of K+, Na+, and Li+ to promote band alignment between ETLs and perovskite. Based on the optimized film quality and energy states of SnO2-Na, the best PSC efficiency of 20.78% is achieved with a significantly enhanced open-circuit voltage of 1.10 V. This work highlights the function of alkali metal salts on the colloid particle distribution and energy level modulation of SnO2.

Preparation of a novel citric acid-crosslinked Zn-MOF/chitosan composite and application in adsorption of chromium(VI) and methyl orange from aqueous solution.

A novel citrate-crosslinked Zn-MOF/chitosan (ZnBDC/CSC) composite was successfully prepared by immobilizing Zn-MOF (ZnBDC) on citrate-crosslinked chitosan (CSC) using citric acid as a chemical bridge. ZnBDC/CSC was characterized by XRD, FT-IR, solid-state 13C NMR, BET and SEM. The adsorption of ZnBDC/CSC for Cr(VI) and MO from aqueous solutions were studied at pH 5.0. The adsorption conditions, such as adsorption time and initial concentration of Cr(VI) and MO solutions were investigated. The results indicated that ZnBDC/CSC showed high adsorption capacity for both Cr(VI) (225 ± 4 mg g-1) and MO (202 ± 3 mg g-1), respectively. The adsorption of Cr(VI) on ZnBDC/CSC could be well described by Langmuir isotherm model, while MO followed Freundlich model. The adsorption kinetic of Cr(VI) and MO demonstrated a better fitness to the pseudo-second order kinetic model. Thermodynamic parameters (enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG)) demonstrated that the adsorption processes of Cr(VI) and MO on ZnBDC/CSC were exothermic, disordered and spontaneous at 298-318 K. The adsorption mechanism of ZnBDC/CSC for Cr(VI) could be mainly explained by electrostatic attraction and cation-π interaction, while for MO, it could be assigned to n-π and π-π interactions, electrostatic attraction and hydrogen bonding. ZnBDC/CSC could be recycled and reused for the removal of Cr(VI) and MO.

Preparation and adsorption properties of citrate-crosslinked chitosan salt microspheres by microwave assisted method.

Citrate-crosslinked chitosan salt (CSC) microspheres were prepared using chitosan as raw material and citric acid as salifying agent by microwave assisted heating method. The product was characterized by XRD, SEM, NMR, TG, FT-IR, GPC and BET. The citric acid solution concentration, microwave reaction temperature and microwave reaction time showed influence on the morphology and size of chitosan citrate salt microspheres. The prepared chitosan citrate salt microsphere showed a high-efficiency adsorption ability to remove Cr(VI) in water. The best adsorbent CSC-2-1H had an ability to absorb Cr(VI) of 172 mg⋅g-1 and reached adsorption equilibrium at 30 min. The adsorption equilibrium data of CSC-2-1H were analyzed with Langmuir and Freundlich adsorption models. The adsorption kinetics and adsorption thermodynamics of Cr (VI) on CSC-2-1H was also analyzed using the pseudo-first-order model, pseudo-second-order model, van't Hoff equation and Arrhenius equation, respectively.

MOF derived ZnO/C nanocomposite with enhanced adsorption capacity and photocatalytic performance under sunlight.

In this work, ZnO/C nanocomposites were obtained by calcining the prepared metal-organic framework precursor under nitrogen. The crystallinity and structure of the prepared products were characterized by XRD, FTIR, XPS and EDS. The morphologies of samples before and after calcination were observed by FESEM. The photocatalytic performances of ZnO/C were evaluated by the degradation of methylene blue under sunlight irradiation. Combined with DRS, PL and BET, the influence of calcination temperature on photocatalytic activities of as-synthesized zinc oxide were discussed as compared with commercial zinc oxide. The results indicated that ZnO/C composite obtained at 600 °C and 700 °C exhibited the superior adsorption capacity and photocatalytic activity. The possible photocatalytic mechanism of ZnO/C nanocomposite for degradation of MB under sunlight irradiation was proposed.

A novel dicationic Quinoline-Carzole fluorescent probe: preparation and labelling of Microthrix parvicella.

A novel dicationic Quinoline-Carbazole fluorescent probe with hydrophobic long-chain alkane was designed and synthesized based on the property of Microthrix parvicella (M. parvicella) in situ utilizing long-chain fatty acids (LCFA) in the activated sludge system. 1H NMR spectrum, ultraviolet-visible (UV-Vis) absorption spectra, and fluorescent spectra analysis demonstrated that the probe was successfully obtained. The probe had a large stokes-shift ranging from 102 to 144 nm in different solvents, which were benefit for the fluorescent labelling properties. The labelling experiment indicated that the prepared probe could absorb onto the surface of M. parvicella through hydrophobic bond. Much stronger yellow fluorescence of M. parvicella was observed at the concentration of 1.0 × 10-5 mol/L when compared with the zooglea, which makes it easy to distinguish M. parvicella from the zooglea. In addition, the photostability of the probe was also investigated, and the result showed that the probe was quite stable in a long period of time. All the results indicated that the prepared probe was suitable for the labelling of M. parvicella.

A Polyoxoniobate/g-C3N4 Nanoporous Material with High Adsorption Capacity of Methylene Blue from Aqueous Solution.

A polyoxoniobate/g-C3N4 nanoporous material with functional groups has been synthesized by using carbon nitride (g-C3N4) and hexaniobate (K8Nb6O19·10H2O, abbreviated as NbO) as precursors. The structure and compositions of the as-prepared nanomaterials were characterized by XRD, FT-IR, FESEM, TEM, and XPS. These two kinds of materials interact with each other forming a hybrid composite, which can be used as an adsorbent for removing a cationic dye (methylene blue, MB) from wastewater with excellent adsorption capacity. Furthermore, parameters that can affect adsorption process including initial dye concentration, pH and temperature were investigated by bath adsorption experiments. The results indicated that the maximum adsorption capacity of NbO/g-C3N4 can reach up to 373.1 mg g-1. Moreover, the equilibrium experiment data fitted Langmuir isotherm well and the adsorption kinetics showed that the pseudo second order model can satisfyingly described MB adsorption kinetics. The thermodynamic analysis indicated that the adsorption was endothermic and spontaneous.

Fabrication of regenerated wool keratin/polycaprolactone nanofiber membranes for cell culture.

Regenerated wool keratin is a promising natural material for tissue engineering. In the present study, l-cysteine redox method was performed to extract keratin from wool. Then the different ratios of keratins blended with polycaprolactone (PCL) in formic acid were electrospun to produce nanofibrous membrane. The morphology, biodegradation degree in phosphate buffer saline (PBS) and cell culture were closely investigated. It is found that adding keratin to the PCL nanofiber can improve the hydrophilicity of the as-spun nanofiber mats and then promote the cell adhesion and proliferation of the composite nanofibrous mats. The nanofiber membrane with the highest hydrophilicity had the highest cellular compatibility.

High-Throughput Synthetic Chemistry Enabled by Organic Solvent Disintegrating Tablet.

Synthetic chemistry remains a time- and labor-intensive process of inherent hazardous nature. Our organic solvent disintegrating tablet (O-Tab) technology has shown potential to make industrial/synthetic chemistry more efficient. As is the case with pharmaceutical tablets, our reagent-containing O-Tabs are mechanically strong, but disintegrate rapidly when in contact with reaction media (organic solvents). For O-Tabs containing sensitive chemicals, they can be further coated to insulate them from air and moisture.

[Influence of different skin reactions of acupoint-application on clinical outcomes in the prevention and treatment of bronchial asthma].

OBJECTIVE: To observe the influence of different skin reactions of acupoint-application in summer on outcomes of prevention and treatment of bronchial asthma. METHODS: All of the bronchial asthma patients were treated with acupoint-application therapy in the dog-days of summer, once every ten days, 3 times altogether. After the treatment, according to scores of the skin reactions including flush, itching, pain, vesicles, etc. induced by acupoint-application of prepared Chinese medical herb paste, 164 cases were divided into four groups: no reaction (n = 43), mild reaction (n = 42), moderate reaction (n = 39) and severe reaction (n = 40). One-year's follow-up was conducted after the treatment for assessing the asthma patients' cough-asthma score, wheezing rale score, and for recording the attack times. RESULTS: After the treatment, the cough-asthma scores, wheezing rale scores, and asthmatic attack times were obviously decreased in all the 4 groups compared to pre-treatment (P < 0.05, P < 0.01). Comparison among the 4 groups showed that the levels of the 3 indexes were significantly higher in the no reaction group and mild reaction group than in the moderate and severe reaction groups after the treatment (P < 0.05, P < 0.01), suggesting a better therapeutic effect in patients undergoing moderate and severe skin reactions. There were no significant differences between the no reaction and mild reaction groups, and between the moderate reaction and severe reaction groups in the levels of the 3 indexes (P > 0. 05). The total effective rates of the no reaction, mild reaction, moderate reaction and severe reaction groups were 58.14%, 88.10%, 94.87% and 97.50%, respectively. The mild, moderate and severe reaction groups were better than the no reaction group in the therapeutic effect (P < 0.01). The mild reaction group was poorer than the moderate and severe reaction groups in clinical efficacy (P < 0.05). There was no marked difference between the moderate and severe reaction groups in clinical outcomes (P > 0.05). CONCLUSION: Acupoint-application in the dog-days can effectively improve the asthma patients' symptoms, and the therapeutic effect of patients experiencing moderate and severe skin reactions was better.