In-Situ Cyclized Polyacrylonitrile as an Electron Selective Layer for n-i-p Perovskite Solar Cell with Enhanced Efficiency and Stability.

In situ cyclized polyacrylonitrile (CPAN) is developed to replace n-type metal oxide semiconductors (TiO2 or SnO2) as an electron selective layer (ESL) for highly efficient and stable n-i-p perovskite solar cells (PSCs). The CPAN layer is fabricated via facile in situ cyclization reaction of polyacrylonitrile (PAN) coated on a conducting glass substrate. The CPAN layer is robust and insoluble in common solvents, and possesses n-type semiconductor properties with a high electron mobility of 4.13×10-3 cm2 V-1 s-1. With the CPAN as an ESL, the PSC affords a power conversion efficiency (PCE) of 23.12 %, which is the highest for the n-i-p PSCs with organic ESLs. Moreover, the device with the CPAN layer holds superior operational stability, maintaining over 90 % of their initial efficiency after 500 h continuous light soaking. These results confirm that the CPAN layer would be a desirable low-cost and efficient ESL for n-i-p PSCs and other photoelectronic devices with high performance and stability.

Electrochemical assembly of single-walled carbon nanotube/polypyrrole/tellurium/lead telluride multi-layer nanocomposite films for room-temperature flexible thermoelectric application.

With the complexity and diversification of thermoelectric (TE) application scenarios, it becomes increasingly difficult for single-component thermoelectric materials to satisfy practical demands. Therefore, recent researches have largely focused on the development of the multi-component nanocomposites, which are probably a good solution for the TE application of some materials that are not eligible when used alone. In this work, a seires of single-walled carbon nanotube (SWCNT)/polypyrrole (PPy)/tellurium (Te)/lead telluride (PbTe) multi-layer flexible composite films were fabricated via the successive electrodeposition of the flexible PPy layer with a low thermal conductivity, the ultra-thin Te induction layer, and the brittle PbTe layer with a large Seebeck coefficient over the pre-fabricated SWCNT membrane electrode with a high electrical conductivity. Through the complementary advantages between different components and the multiple synergies of the interface engineering, the SWCNT/PPy/Te/PbTe composites harvested the excellent TE performance with a maximum power factor (PF) of 929.8 ± 35.4 µW m-1 K-2 at room temperature, outperforming those of most of the electrochemically-prepared organic/inorganic TE composites reported previously. This work evidenced that the electrochemical multi-layer assembly is a feasible tactic for constructing special thermoelectric materials to meet customized requirements, which could also be applied to other material platforms.

Full-Electrochemical Construction of High-Performance Polypyrrole/Tellurium Thermoelectrical Nanocomposites.

As one of the most attractive inorganics to improve the thermoelectric (TE) performance of the conducting polymers, tellurium (Te) has received intense concern due to its superior Seebeck coefficient (S). However, far less attention has been paid to polypyrrole (PPy)/Te TE composites to date. In this work, we present an innovative full-electrochemical method to architect PPy/Te TE composite films by sequentially depositing Te with large S and PPy with high electrical conductivity (σ). Consequently, the PPy/Te composite films achieved excellent TE performance, with the largest power factor (PF) reaching up to 234.3 ± 4.1 µW m-1 K-2. To the best of our knowledge, this value approaches the reported highest PF record (240.3 ± 5.0 µW m-1 K-2) for PPy-based composites. This suggests that the modified full-electrochemical method is a feasible and effective strategy for achieving high-performance TE composite films, which would probably provide a general guideline for the design and preparation of excellent TE materials in the future.

[Effects of altitude on circulating endothelial progenitor cells and hypoxia-inducible factor-1α in patients with type 2 diabetes].

Objective: To compare the changes in the number of circulating endothelial progenitor cells and hypoxia-inducible factors in patients with type 2 diabetes at different altitudes, and to provide a basis for the research and treatment of type 2 diabetes vascular complications. Methods: Selected Type 2 diabetes patients who were diagnosed in a low altitude area of 386 m (Xianyang City) and a high altitude area of 1 520 m (Lanzhou) (25 persons/29 persons) and healthy persons (20 persons/20 persons) were selected. An automatic biochemical analyzer was used to detect the indexes of blood lipids, blood glucose, and glycosylated hemoglobin of the two groups of people, and the concentration of Hypoxia inducible factor-1α (HIF-1α) was detected by enzyme-linked immunosorbent assay (ELISA). The number of circulating endothelial progenitor cells (EPCs) in peripheral blood was determined by a cytometer. Results: No matter in low or high altitude areas, the number of circulating EPCs in the diabetes group was lower than that in the healthy group (P＜0.01). The levels of body mass index (BMI), waist to hip ratio (WHR), triglyceride (TG), fasting blood glucose (FBG) and glycosylated hemoglobin (HbAlc) were increased (P＜0.05). Compared with the low-altitude group, the expression levels of HIF-1α in diabetic patients at high-altitude and healthy people were increased significantly (P＜0.05), while the number of circulating EPCs was decreased significantly (P＜0.05), and the number of circulating EPCs in healthy people or the patients with type 2 diabetes without vascular complications was higher than that of patients with type 2 diabetes with vascular complications (P＜0.05). Conclusion: With the increase in altitude, the expression level of HIF-1α in type 2 diabetes mellitus(T2DM)patients is increased, and the number of circulating EPCs is decreased, which is closely related to the degree of vascular disease. Therefore, it is possible through transplantation of EPCs for high altitude T2DM patients to achieve the prevention and improvement of diabetic vascular complications.

Pseudo in situ construction of high-performance thermoelectric composites with a dioxothiopyrone-based D-A polymer coating on SWCNTs.

Organic polymer/inorganic particle composites with thermoelectric (TE) properties have witnessed rapid progress in recent years. Nevertheless, both development of novel polymers and optimization of compositing methods remain highly desirable. In this study, we first demonstrated a simulated in situ coagulation strategy for construction of high-performance thermoelectric materials by utilizing single-walled carbon nanotubes (SWCNTs) and a new D-A polymer TPO-TTP12 that was synthesized via incorporating dioxothiopyrone subunit into a polymeric chain. It was proven that the preparation methods have a significant influence on thermoelectric properties of the TPO-TTP12/SWCNT composites. The in situ prepared composite films tend to achieve much better thermoelectric performances than those prepared by simply mixing the corresponding polymer with SWCNTs. As a result, the in situ compositing obtains the highest Seebeck coefficient of 66.10 ± 0.05 µV K-1 at the TPO-TTP12-to-SWCNT mass ratio of 1/2, and the best electrical conductivity of up to 500.5 ± 53.3 S cm-1 at the polymer/SWCNT mass ratio of 1/20, respectively; moreover, the power factor for the in situ prepared composites reaches a maximum value of 141.94 ± 1.47 µW m-1 K-2, far higher than that of 104.68 ± 0.86 µW m-1 K-2 for the by-mixing produced composites. This indicates that the dioxothiopyrone moiety is a promising building block for constructing thermoelectric polymers, and the simulated in situ compositing strategy is a promising way to improve TE properties of composite materials.

Organic-inorganic hybrid perovskite for low-cost and high-performance xerographic photoreceptors.

Solution-processable organic-inorganic hybrid perovskites are being widely investigated for many applications, including solar cells, light-emitting diodes, photodetectors, and lasers. Herein, we report, for the first time, successful fabrication of xerographic photoreceptors using methylammonium lead iodide (CH3NH3PbI3) perovskite as a light-absorbing material. With the incorporation of polyethylene glycol (PEG) into the perovskite film, the ion migration inherent to the perovskite material can be effectively suppressed, and the resulting photoreceptor exhibits a high and panchromatic photosensitivity, large surface potential, low dark decay, and high environmental resistance and electrical cycling stability. Specifically, the energies required to photodischarge one half of the initial surface potential (E 0.5) are 0.074 µJ cm-2 at 550 nm and 0.14 µJ cm-2 at 780 nm, respectively. The photosensitivites outmatch those of the conventionally used organic pigments having narrow spectral responses. Our findings inform a new generation of highly efficient and low-cost xerographic photoreceptors based on perovskite materials.

t-BuOK-catalysed alkylation of fluorene with alcohols: a highly green route to 9-monoalkylfluorene derivatives.

A simple, mild and efficient protocol was developed for the alkylation of fluorene with alcohols in the presence of t-BuOK as catalyst, affording the desired 9-monoalkylfluorenes with near quantitative yields in most cases.

A macrocycle-assisted nanoparticlization process for bulk Ag2S.

We report herein a new nanoparticlization process for the bulk-to-nano transformation of Ag2S by incorporating both top-down and bottom-up approaches. Bulk Ag2S was dissolved in solution with the assistance of a macrocyclic ligand, hexamethylazacalix[6]pyridine (Py[6]), to produce polynuclear silver sulfide cluster aggregates. All Ag-S cluster aggregates obtained in three crystalline complexes were protected by Py[6] macrocycles. Removing the protective Py[6] macrocycles by protonation led to the generation of unconventional Ag-S nanoparticles with a large energy gap. Theoretical calculations by a hybrid DFT method demonstrated that the silver sulfide clusters with high Ag/S ratio exhibited more localized HOMO-LUMO orbitals, which consequently enlarged their band gap energies. These experimental and theoretical studies broaden our understanding of the fabrication of nanomaterials by virtue of the advantages of both bottom-up and top-down methods and meanwhile provide a viable means of adjusting the band gap of binary nanomaterials independent of their size.

Designed synthesis of a metal cluster-pillared coordination cage.

An unprecedented polynuclear metal cluster-pillared triangular prism was built by a macrocycle-directing strategy. Discrete architectures of three silver cluster-involved metallosupramolecules were characterized by single crystal X-ray crystallography and spectroscopy studies.

Dual templated synthesis of silver acetylide cluster-encapsulated supramolecular boxes.

A dual-templated approach for the controllable synthesis of metal cluster complexes is described. By using an acetylide-containing anion with specific geometry as a central template and a macrocyclic coordinative compound as a peripheral one, two multinuclear silver-acetylide cluster-encapsulated supramolecular boxes were synthesized.

Stabilization of a reactive polynuclear silver carbide cluster through the encapsulation within a supramolecular cage.

We report herein the synthesis of a new metal cluster-encapsulated supramolecular capsule, [(C≡C)@Ag(5-6)@(Py6)(2)](CF(3)SO(3))(3-4) (3, Py6 = azacalix[6]pyridine), by use of a bowl-shaped macrocyclic ligand Py6. The multinuclear silver carbide cluster aggregate in 3 is encapsulated by two Py6 ligands through both metal-ligand coordination and cation-π interactions, spotlighting a new synthetic strategy for supramolecular capsules.

Designed synthesis of metal cluster-centered pseudo-rotaxane supramolecular architectures.

The designed synthesis and structural characterization of two metal cluster-centered metallosupramolecular architectures are reported. In complex [(CF(3)SO(3))Ag(4)((t)BuC≡C)(Py8)](CF(3)SO(3))(2) (1) and [(CF(3)SO(3))Ag(4){C≡C-(m-C(6)H(4))-C≡C-(m-C(6)H(4))-C≡C-(m-C(6)H(4))-C≡C}Ag(4)(CF(3)SO(3))(Py8)(2)](CF(3)SO(3))(4) (2), organic acetylide ligands are utilized to induce the formation of polynuclear silver aggregates, which are encapsulated into the central cavity of the neutral macrocyclic compound azacalix[8]pyridine (Py8). The tetrasilver cluster centered [2]- and [3]-pseudo-rotaxane structures are obtained and fully characterized by X-ray crystallography, ESI mass spectrometry, and (1)H NMR spectroscopy.

Nickel-catalyzed cross-coupling of diarylamines with haloarenes.

The cross-coupling reaction of diarylamines with aryl bromides/iodides can be effected by the Ni(ii)-(sigma-aryl) complex/PPh(3)/NaH system, and a preliminary investigation was conducted into the mechanism of this reaction.

Nickel-catalyzed amination of aryl tosylates.

The cross-coupling of aryl tosylates with amines and anilines was accomplished by using a Ni-based catalyst system from the combination of Ni(II)-(sigma-aryl) complexes/N-heterocyclic carbenes (NHCs). The feature, scope, and limitation of this reaction are disclosed.