Grain Engineering of Sb2 S3 Thin Films to Enable Efficient Planar Solar Cells with High Open-Circuit Voltage.

Sb2 S3 is a promising environmentally friendly semiconductor for high performance solar cells. But, like many other polycrystalline materials, Sb2 S3 is limited by nonradiative recombination and carrier scattering by grain boundaries (GBs). This work shows how the GB density in Sb2 S3 films can be significantly reduced from 1068 ± 40 to 327 ± 23 nm µm-2 by incorporating an appropriate amount of Ce3+ into the precursor solution for Sb2 S3 deposition. Through extensive characterization of structural, morphological, and optoelectronic properties, complemented with computations, it is revealed that a critical factor is the formation of an ultrathin Ce2 S3 layer at the CdS/Sb2 S3 interface, which can reduce the interfacial energy and increase the adhesion work between Sb2 S3 and the substrate to encourage heterogeneous nucleation of Sb2 S3 , as well as promote lateral grain growth. Through reductions in nonradiative recombination at GBs and/or the CdS/Sb2 S3 heterointerface, as well as improved charge-carrier transport properties at the heterojunction, this work achieves high performance Sb2 S3 solar cells with a power conversion efficiency reaching 7.66%. An impressive open-circuit voltage (VOC ) of 796 mV is achieved, which is the highest reported thus far for Sb2 S3 solar cells. This work provides a strategy to simultaneously regulate the nucleation and growth of Sb2 S3 absorber films for enhanced device performance.

Tailoring a Nanochaperone to Regulate α-Synuclein Assembly.

Protein misassembly leads to the formation of dysfunctional and toxic molecular species relating to neurodegeneration in Parkinson's disease and Alzheimer's disease. Here, we tailored a nanochaperone (αS-nChap) for α-synuclein to regulate its assembly. The αS-nChap is capable of i) specifically recognizing α-synuclein; ii) dynamically capturing and stabilizing monomeric α-synuclein and retarding oligomerization; iii) tightly capturing oligomeric α-synuclein to prevent fibrillization; and iv) transporting α-synuclein oligomers to the lysosomal degradation system. The regulation of α-synuclein assembly by αS-nChap was studied in vitro. Moreover, the role of αS-nChap preventing α-synuclein pathology in cells and protecting neurons from apoptosis was investigated. The strategy of tailoring a nanochaperone to regulate aberrant assembly of pathogenic proteins provides important insights into protein misfolding diseases. We foresee that αS-nChap has therapeutic value for Parkinson's disease.

Magnetron sputtered ZnO electron transporting layers for high performance perovskite solar cells.

An ideal electron transporting layer (ETL) of perovskite solar cells (PSCs) requires reasonable energy levels, high electrical conductivity and excellent charge extraction. The low processing temperature makes ZnO a promising ETL for PSCs; however the widely used solution-processed ZnO films often suffer from high-density surface defect states, which might cause severe charge recombinations at the ETL/perovskite interface and accelerate the chemical decomposition of perovskite materials. In this work, we employed the vacuum-based magnetron sputtering method to deposit ZnO ETLs, which significantly reduces the number of oxygen vacancies and hydroxyl groups on the ZnO surface. The magnetron sputtered ZnO based CH3NH3PbI3 PSCs yield a considerable power conversion efficiency (PCE) of 13.04% with excellent long-term device stability. Furthermore, aiming to improve the ETL/perovskite interface for more efficient electron extraction, a bilayer ZnO/SnO2 ETL was designed for constructing high-efficiency PSCs. The detailed morphology characterization confirms that the bilayer ZnO/SnO2 provides a low-roughness film surface for the deposition of high-quality perovskite films with full coverage and long-range continuity. The carrier dynamic study reveals that the presence of the SnO2 layer results in the formation of favorable cascade energy alignments and facilitates the electron extraction at the ETL/perovskite interface. As a result, compared with the ZnO-based PSCs, the device constructed with the bilayer ZnO/SnO2 ETL delivers an improved PCE of 15.82%, coupled with a reduced hysteresis.

Self-Assembled Nanochaperones Inhibit the Aggregation of Human Islet Amyloid Polypeptide Associated with Type 2 Diabetes.

Human islet amyloid polypeptide (hIAPP) aggregation is closely associated with dysfunction and apoptosis of pancreatic ß-cells in type 2 diabetes (T2D). Accordingly, hIAPP amyloid inhibitors have shown promise against T2D. Here, by mimicking the function of natural molecular chaperones, nanochaperones (nChaps) based on self-assembled polymeric micelles with tunable surface microdomains for T2D treatment are reported. By capturing the aggregation-prone species of hIAPP onto the hydrophobic microdomains and segregating them by hydrophilic PEG chains, this kind of nChaps could effectively prevent hIAPP aggregation, block cell adhesion of hIAPP, facilitate hIAPP aggregates degradation and reduce hIAPP-related cytotoxicity. Therefore, our work will provide useful insights to develop a biomimetic strategy for the treatment of T2D.

Photochemical pollutant degradation on facet junction-engineered TiO2 promoted by organic arsenical: Governing roles of arsenic-terminated surface chemistry and bulk-free radical speciation.

Photochemical oxidation based on semiconducting metal oxides is an efficient strategy to remove environmental pollutants in water, air and soil. The fine manipulation of photo-carriers separation, surface chemistry and radical speciation is of considerable interest for environmental remediation. In this work, the morphology- and structure-tailored TiO2 single crystals with epitaxial {101}/{001} facet junction were designed, prepared and tested for photochemical pollutant oxidation in the presence of organic arsenicals, the main component in swine wastewater from livestock industry, although they have been forbidden for several years. The facet junction-tailored TiO2 deserved an efficient photo-carriers separation with high quantum efficiency. The photochemical oxidation of 4-chlorophenol (4-CP), phenol and bisphenol A (BPA) was substantially improved by roxarsone (ROX). ROX-enhanced photochemical activity of TiO2 was mainly attributed to the in-situ arsenic-terminated surface chemistry by Ti-OAsVO3/-OAsIIIO2. This surface played governing roles in water/TiO2 interactions, and changed water adsorption from dissociative to molecular configuration. Furthermore, ·OH was finely regulated from low-activity surface-bound to high-activity bulk-free speciation between as-generated photo-holes with free water molecules. Our findings provided a new chance to refine the TiO2-based photochemical oxidation, and a modifying technology to treat swine wastewater from livestock industry with much reduced secondary pollution.

Copper selenide (Cu3Se2 and Cu2-xSe) thin films: electrochemical deposition and electrocatalytic application in quantum dot-sensitized solar cells.

In this work, high crystallinity copper selenide thin films directly deposited onto conducting substrates were obtained through a potentiostatic electrodeposition approach. The as-deposited copper selenides involve annealing induced phase transformation from tetragonal Cu3Se2 to cubic Cu2-xSe. The annealing also leads to a remarkable morphology change from dendritic nanosheets to connected networks and separated particle shapes for the annealed (A-Cu2-xSe) and selenized (S-Cu2-xSe) samples, respectively. The copper selenide thin films were demonstrated to serve as efficient counter electrodes (CEs) in quantum dot-sensitized solar cells (QDSCs) for electrocatalyzing polysulfide electrolyte regeneration. The CdS/CdSe QDSCs constructed with copper selenide CEs deliver considerable power conversion efficiencies (PCEs), especially an optimal value of 3.89% for the A-Cu2-xSe CE-based device. The enhanced photovoltaic performance benefits from the connected network microstructure of A-Cu2-xSe films which afford a large number of reaction sites and efficient charge transport pathways. The Tafel polarization characterization further indicates that, in contrast to the commonly used Cu2S and Pt CEs, the non-stoichiometric Cu2-xSe CE exhibits better electrochemical catalytic activity. This work highlights the great potential of electrodeposition for fabricating promising copper selenide CEs for high performance QDSCs.

Nearly monodisperse PbS quantum dots for highly efficient solar cells: an in situ seeded ion exchange approach.

A facile in situ seeded ion exchange approach was used to produce nearly monodisperse and uniformly distributed PbS quantum dots (QDs) on mesoporous TiO2 films. This strategy solves the size distribution problem for conventional SILAR-processed QDs and shows promise for constructing high-performance near-infrared-responsive PbS QD solar cells.

Ar plasma irradiation improved optical and electrical properties of TiO2/Ag/TiO2 multilayer thin film.

Embedding a thin metal layer between two thin dielectric or semiconductor layers [dielectric/metal/dielectric (DMD)] leads to a kind of transparent electrode that is promising as a substitute for the currently widely applied indium tin oxide electrode. However, the optical and electrical properties of DMD still wait for further improvement. In this study, Ar plasma irradiation (API) was, for the first time to our knowledge, applied to improve the optical and electrical properties of a TiO2/Ag/TiO2 electrode that was fabricated by electron-beam evaporation of TiO2 and electric-resistance heating of high purity Ag under vacuum. Ar plasma was produced by radio frequency glow discharge. The Ag layer was bombarded before the second layer of TiO2 was deposited. The electrode with configuration of TiO2 (24 nm)/Ag(14 nm)/TiO2 (24 nm) after API for 10 s shows excellent performance. The mean transmittance between 370 and 800 nm reaches 94% and the sheet resistance is as low as 6 Ω/sq, while Haacke's figure of merit is as high as 112×10(-3) Ω(-1). The improvement mechanism is discussed based on field emission scanning electron microscope images and absorption spectra. The improvement is attributed to the fact that API reduces the localized surface plasmon resonance of Ag nanoparticles and makes the Ag film thinner and denser.

Enhanced sorption of radiocobalt from water by Bi(III) modified montmorillonite: a novel adsorbent.

In this study, Ca-montmorillonite (Ca-Mt) modified with Bi(3+) was used as a novel adsorbent for the sorption of Co(II) from aqueous solutions. The sorption of Co(II) on Bi-montmorillonite (Bi-Mt) was investigated as a function of contact time, pH, ionic strength, adsorbent content, Co(II) concentrations, fulvic acid (FA) and temperature. Compared to Ca-Mt, Bi-Mt showed a higher affinity to bind Co(II) ions. The sorption percentage of Co(II) on Bi-Mt increased with increasing pH at pH 3.0-8.5, and then maintained the high level at pH 8.5-12. The sorption of Co(II) on Bi-Mt was dependent on ionic strength at low pH, and independent of ionic strength at high pH. The presence of FA enhanced Co(II) sorption at low pH, but suppressed Co(II) sorption at high pH. The thermodynamic data derived from temperature dependent sorption isotherms suggested that the sorption of Co(II) on Bi-Mt was spontaneous and endothermic process. Outer-sphere surface complexation and/or ion exchange were the main mechanisms of Co(II) sorption on Bi-Mt at low pH, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, it is possible to conclude that Bi-Mt is suitable for application of Co(II) removal from aqueous solutions.