Application of a BC501A Liquid Scintillation Detector with a Gain Stabilization System on the EAST Tokamak

A 2＂×2＂BC501A liquid scintillation detector with a gain stabilization system is developed and applied to neutron andγ-ray measurement on the EAST tokamak.Energy calibration of a liquid scintillator using a fast coincidence method is presented and compared with the Monte Carlo simulation.Determination of the proton light output function of the BC501A is presented.Results from dedicated experiments with an Am-Be neutron source,γsource and quasi-monoenergetic neutron beams,and from measurements on EAST tokamak are presented and discussed.

SYNTHESIS AND CHARACTERIZATION OF NEW STABILIZERS WITH OPTIMAL MOLECULAR WEIGHT

Over 2 x 10(8) tons of polymers are produced every year, and a large portion of polymers faces the degradation problem. There are many effective methods to protect polymers against degradation and the addition of stabilizers to polymer remains the most convenient and effective way of enhancing polymer life and performance. In this article, a series of effective stabilizers with optimal molecular weight (MW), including common, monomeric and polymeric stabilizers (antioxidant and light stabilizer) were synthesized using isocyanation, controlled isocyanation, hydrosilylation, epoxide addition, macroreaction of stabilizing functional compounds and polymerization of monomeric stabilizers. The structure and performance of these new stabilizers were characterized by using IR, NMR, MS, UV-spectra, XPS and elemental analysis. The current development of stabilizer synthesis was also reviewed.

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn-Pb Alloyed Perovskites for High-Performance Solar Cells

The complete elimination of methylammonium(MA)cations in Sn-Pb composites can extend their light and thermal stabilities.Unfortunately,MA-free Sn-Pb alloyed perovskite thin films suffer from wrinkled surfaces and poor crystallization,due to the coexistence of mixed intermediate phases.Here,we report an additive strategy for finely regulating the impurities in the intermediate phase of Cs_(0.25)FA_(0.75)Pb_(0.6)Sn_(0.4)I_(3)and,thereby,obtaining high-performance solar cells.We introduced d-homoserine lactone hydrochloride(D-HLH)to form hydrogen bonds and strong Pb-O/Sn-O bonds with perovskite precursors,thereby weakening the incomplete complexation effect between polar aprotic solvents(e.g.,DMSO)and organic(FAI)or inorganic(CsI,PbI_(2),and SnI_(2))components,and balancing their nucleation processes.This treatment completely transformed mixed intermediate phases into pure preformed perovskite nuclei prior to thermal anneal-ing.Besides,this D-HLH substantially inhibited the oxidation of Sn^(2+) species.This strategy generated a record efficiency of 21.61%,with a Voc of 0.88 V for an MA-free Sn-Pb device,and an efficiency of 23.82%for its tandem device.The unencapsulated devices displayed impressive thermal stability at 85℃ for 300 h and much improved continuous operation stability at MPP for 120 h.

Mixed d/f Complexes Zn(H2L)Ln(NO3)3(Ln=Sm,Tb and Dy)：Crystal Structure,Fluorescence and Thermal Stability

A series of isostructural d/f molecular compounds Zn（H2L）Ln（NO3）3·CH3OH（Ln = Dy（1）, Tb（2） and Sm（3）） were synthesized by the introduction of a designed multifunctional ligand N,N？,N？？,N？？？-tetra（2-hydroxy-3-methoxy-5-methylbenzyl）-1,4,7,10-tetraazacyclododecan（H4L = C（44）H（60）N4O8）. In the isostructural molecules, each crystallographically independent Zn2＋ and Ln3＋ centers are connected by two phenolic oxygen atoms. For the six-coordinate Zn-（2＋） ion, the coordination geometry can be viewed as a regular bicapped square pyramid. While for the ten-coordinate Ln-（3＋） ion, if each O,O？-chelated nitrate ligand is seen as a single coordination site, the coordination geometry can be viewed as a distorted pentagonal bipyramid. The fluorescent spectra show that compounds 2 and 3 exhibited characteristic sharp emissions of Tb-（3＋） and Sm-（3＋）, respectively, while compound 1 was found to be a single-component white-light-emitting complex in the solid state. Thermal stabilities of the three compounds were investigated by using thermal gravimetric analysis. In addition, the thermal decomposition of compound 1 was confirmed by temperature-dependent powder X-ray diffraction technique.

Effect of Photostablizers on Surface Color and Mechanical Property of Wood-flour/HDPE Composites after Weathering

The effects of photostabilizers of ultraviolet absorbers （UVA）, hindered amine light stabilizer （HALS） and pigment on surface color change and mechanical properties of weathered wood-flour/ polyethylene （HDPE） composites were investigated. After being added UVA with high UV absorbance, the WPC exhibites better ability to resist color fading and mechanical property loss. High molecular weight HALS is found to be the most effective in controlling long term fading and yellowing changes. Pigments cover the composites for remaining the original color after weathering regardless of less contribution to mechanical property. Addition of photostabilizer and pigment together show great synergism in decreasing color fading and flexural property loss.

A Convenient Synthesis and Properties of Ru(bpy)_2[bpy(CO_2H)-(CO_2Et)](PF_6)_2 Photosensitive Dye

A novel Ru(Ⅱ) tris-bipyridyl complex, Ru(bpy)2[bpy(CO2H)(CO2Et)][PF6]2 is prepared in a simple and convenient process. It will be an alternativ?of Ru(bpy)2bpy(CO2Et)2(PF6)2 to be used in solar cel須 as photosensitive dyes.

Effect of Organosilicon Coating Containing Light Stabilizer on UV Aging Resistance of Bitumen

Effects of organosilicon coating with light stabilizer UV326,UV531 and 770 on ultraviolet (UV) aging resistance of bitumen were investigated by testing the viscosity,softening point and the changes of chemical component before and after UV aging. The results show that UV aging resistance of bitumen is improved due to the good weatherability of organosilicon. And the UV aging resistance of bitumen is further enhanced by adding light stabilizer into organosilicon coating due to the good UV absorption of light stabilizers. Bitumen coated with organosilicon coating containing UV326 exhibits better UV aging resistance in comparison with bitumen coated with organosilicon containing UV531 or 770.

Improving Ultraviolet Stability of Perovskite Solar Cells via Singlet Fission Down-Conversion

The instability of perovskite materials under continuous ultraviolet(UV)light irradiation and high sensitivity in humid environments remain obstacles to future commercialization.Especially,the photovoltaic performance of perovskite solar cells(PVSCs)is prone to decline under UV light exposure for sustained periods of time.However,in conventional methods,preventing UV light from entering PVSCs usually comes at the expense of reducing short circuit photocurrent(Jsc).Herein,the UV stability of PVSCs is modified by in-troducing a singlet fission down-conversion layer 6,13-bis(triisopropylsilylethynyl)pentacene(TIPS-PEN)via one-step anti-solvent method without sacrificing device efficiency.The introduction of down conversion layer can not only improve the Jsc by converting UV light into multiple excitons,but also enhance the open-circuit voltage(Voc)owing to a better matched energy level alignment at the perovskite/spiro-OMeTAD interface.Consequently,the TIPS-PEN incorporated PVSCs attain the champion power conversion effi-ciency(PCE)up to 22.92%accompanied with dramatically increased UV photostability which can retain 80%of its primitive PCE un-der continuous UV light soaking for 150 h.Moreover,the unencapsulated PVSCs with TIPS-PEN exhibit remarkable moisture stability which can sustain over 80%of the initial value under air conditions(50%relative humidity,25℃)after 1000 h.

Improving intrinsic stability for perovskite/silicon tandem solar cells

Monolithic hybrid halide perovskite/crystalline silicon(c-Si)tandem solar cells have demonstrated their great potential to surpass the theoretical efficiency limit of single-junction devices.However,the stability of perovskite sub-cells is inferior to that of the c-Si solar cells that have been commercialized,casting serious doubt about the lifetime of the entire device.During device operation,light and heat are inevitable,which requires special attention.Herein,we review the current understandings of the intrinsic stability of perovskite/c-Si tandems upon light and/or heat aging.First,we summarize the recent understandings regarding light facilitated ion migration,materials decomposition,and phase segregation.In addition,the reverse bias effect on the stability of tandem modules caused by uneven illumination is discussed.Second,this review also summarizes the thermalinduced degradation and mismatch issue,which underlines the system design of perovskite/c-Si tandems.Third,recent strategies to improve the intrinsic stability of perovskite/c-Si tandems under light and/or heat are reviewed,such as composition engineering,crystallinity enhancement,interface modification,material optimization,and device structure modification.At last,we present several potential research directions that have been overlooked,and hope those are helpful for future research on perovskite based tandem solar cells.

The stability of inorganic perovskite solar cells:from materials to devices

Inorganic halide perovskite solar cells(IHPSCs)have become one of the most promising research hotspots due to to the excellent light and thermal stabilities of inorganic halide perovskites(IHPs).Despite rapid progress in cell performance in very recent years,the phase instability of IHPs easily occurs,which will remarkably influence the cell efficiency and stability.Much effort has been devoted to solving this issue.In this review,we focus on representative progress in the stability from IHPs to IHPSCs,including(i)a brief introduction of inorganic perovskite materials and devices,(ii)some new additives and fabrication methods,(iii)thermal and light stabilities,(iv)tailoring phase stability,(v)optimization of the stability of inorganic perovskite solar cells and(vi)interfacial engineering for stability enhancement.Finally,perspectives will be given regarding future work on highly efficient and stable IHPSCs.This review aims to provide a thorough understanding of the key influential factors on the stability of materials to highly efficient and stable IHPSCs.

Self-assembled core-shell polydopamine@MXene with synergistic solar absorption capability for highly efficient solar-to-vapor generation

As a renewable and environment-friendly technology for seawater desalination and wastewater purification,solar energy triggered steam generation is attractive to address the long-standing global water scarcity issues.However,practical utilization of solar energy for steam generation is severely restricted by the complex synthesis,low energy conversion efficiency,insufficient solar spectrum absorption and water extraction capability of state-of-the-art technologies.Here,for the first time,we report a facile strategy to realize hydrogen bond induced self-assembly of a polydopamine(PDA)@MXene microsphere photothermal layer for synergistically achieving wide-spectrum and highly efficient solar absorption capability(≈96%in a wide solar spectrum range of 250–1,500 nm wavelength).Moreover,such a system renders fast water transport and vapor escaping due to the intrinsically hydrophilic nature of both MXene and PDA,as well as the interspacing between core-shell microspheres.The solar-to-vapor conversion efficiencies under the solar illumination of 1 sun and 4 sun are as high as 85.2%and 93.6%,respectively.Besides,the PDA@MXene photothermal layer renders the system durable mechanical properties,allowing producing clean water from seawater with the salt rejection rate beyond 99%.Furthermore,stable light absorption performance can be achieved and well maintained due to the formation of ternary TiO2/C/MXene complex caused by oxidative degradation of MXene.Therefore,this work proposes an attractive MXene-assisted strategy for fabricating high performance photothermal composites for advanced solar-driven seawater desalination applications.

Band gap engineered polymeric-inorganic nanocomposite catalysts:Synthesis, isothermal stability, photocatalytic activity and photovoltaic performance

Polymeric-inorganic nanocomposite catalysts were synthesized by facile one-pot chemical polymerization of pyrrole in the presence of titanium dioxide nanoparticles. The electrical, optical, photovoltaic performance of dye sensitized solar cell（DSSC） and visible light driven photocatalytic activities of the nanocomposite were investigated. The prepared nanocomposite displays excellent photo-activity, attaining 100% degradation of methyl orange dye in 60 min under visible light source while 55% for pure TiO_2 under similar experimental conditions. The photovoltaic performance of the polypyrrole-titanium dioxide（PPy-TiO_2） nanocomposite has a 51.4% improvement with a photo-conversion efficiency of 8.07% as compared to pure TiO_2 based DSSC. By comparing the physical mixture of the PPy-TiO_2 nanocomposite and pristine TiO_2, the enhanced activity of the PPy-TiO_2 nanocomposite can be attributed to the reduced charge transfer resistance, outstanding electrical conductance of the PPy, the nano-sized structure of TiO_2 and their synergetic effect. Furthermore, the PPy-TiO_2 nanocomposite shows excellent electrical conductivity and isothermal stability under ambient conditions below 110？C.

Photo-stable perovskite solar cells with reduced interfacial recombination losses using a CeO interlayer

Despite demonstrating remarkable power conversion efficiencies(PCEs), perovskite solar cells(PSCs) have not yet achieved their full potential. In particular, the interfaces between the perovskite and charge transport layers account for the vast majority of the recombination losses.Interfacial contact and band alignment between the lowtemperature-processed TiO_(2) electron transport layer(ETL)and the perovskite are essential to minimize nonradiative recombination losses. In this study, a CeOx interlayer is employed to modify the perovskite/TiO_(2) interface, and the charge transport properties of the devices are investigated. The bilayer-structured TiO_(2)/CeOx ETL leads to the modification of the interface energetics, resulting in improved electron extraction and reduced nonradiative recombination in the PSCs.Devices based on TiO_(2)/CeOx ETL exhibit a high open-circuit voltage(Voc) of 1.13 V and an enhanced PCE of more than 20%as compared with Vocof 1.08 V and a PCE of approximately 18% for TiO^(2-)based devices. Moreover, PSCs based on TiO_(2)/CeOx ETL maintain over 88% of their initial PCEs after light illumination for 300 min, whereas PSCs based on TiO_(2) ETL almost failed. This study provides an efficient strategy to enhance the PCE and stability of PSCs based on a lowtemperature-processed TiO_(2) ETL.