Effect of drying methods on perovskite films and solar cells

The high efficiency,solution processibility,and flexibility of perovskite solar cells make them promising candidates for the photovoltaic industry[1−8].The deposition method is one of the most critical factors that affect the performance of perovskite films.Various deposition methods have been developed to make perovskite films,including spin-coating,slotdie coating.

Flexible Nanocomposite Conductors for Electromagnetic Interference Shielding

With the extensive use of electronic communication technology in integrated circuit systems and wearable devices, electromagnetic interference(EMI) has increased dramatically. The shortcomings of conventional rigid EMI shielding materials include high brittleness, poor comfort, and unsuitability for conforming and deformable applications. Hitherto, flexible(particularly elastic) nanocomposites have attracted enormous interest due to their excellent deformability. However, the current flexible shielding nanocomposites present low mechanical stability and resilience, relatively poor EMI shielding performance, and limited multifunctionality. Herein, the advances in low-dimensional EMI shielding nanomaterials-based elastomers are outlined and a selection of the most remarkable examples is discussed. And the corresponding modification strategies and deformability performance are summarized. Finally, expectations for this quickly increasing sector are discussed, as well as future challenges.

转录组分析在血液样本时间和供体特征刻画中的应用研究

案件现场生物物证信息深度挖掘与刻画,可以为案件侦查、涉案人员查找提供丰富可靠线索,是当前法医DNA检验的有效补充,也是国内外法庭科学的研究热点之一。本研究以血液样本为研究对象,证实了0~168天内离体血液样本转录组变化的时间相关性,并建立随机森林模型实现不同离体时间血液样本分类。同时,进一步证实相同离体时间段内,不同吸烟习惯和不同性别供体来源的血液样本转录本具有显著差异,HLA-DRB1、HLA-DQB1和HLA-DQA2可以作为供体吸烟习惯判别标志,Y染色体非重组区(non-recombining Y,NRY)的转录本RPS4Y1和EIF1AY可以作为供体性别特征判别标志。本研究为法庭科学领域建立基于转录组分析的血液样本遗留时间和供体特征刻画方法提供了理论基础和实验依据。

Optimizing the Performance of CsPbI3-Based Perovskite Solar Cells via Doping a ZnO Electron Transport Layer Coupled with Interface Engineering

Interface engineering has been regarded as an effective and noninvasive means to optimize the performance of perovskite solar cells(PSCs).Here,doping engineering of a ZnO electron transport layer(ETL)and CsPbI3/ZnO interface engineering via introduction of an interfacial layer are employed to improve the performances of CsPbI3-based PSCs.The results show that when introducing a TiO2 buffer layer while increasing the ZnO layer doping concentration,the open-circuit voltage,power conversion efficiency,and fill factor of the CsPbI3-based PSCs can be improved to 1.31 V,21.06%,and 74.07%,respectively,which are superior to those of PSCs only modified by the TiO2 buffer layer or high-concentration doping of ZnO layer.On the one hand,the buffer layer relieves the band bending and structural disorder of CsPbI3.On the other hand,the increased doping concentration of the ZnO layer improves the conductivity of the TiO2/ZnO bilayer ETL because of the strong interaction between the TiO2 and ZnO layers.However,such phenomena are not observed for those of a PCBM/ZnO bilayer ETL because of the weak interlayer interaction of the PCBM/ZnO interface.These results provide a comprehensive understanding of the CsPbI3/ZnO interface and suggest a guideline to design high-performance PSCs.

Memory stem T cells generated by Wnt signaling from blood of human renal clear cell carcinoma patients

Objective: Memory stem T cells(Tscm) have attracted attention because of their enhanced self-renewal, multipotent capacity, and anti-tumor capacities. However, little is known about Tscm in patients with renal clear cell carcinoma(RCC) and the role of Wnt signaling in these cells. We evaluated Tscm from RCC patients concerning their activation of Wnt signaling in vitro and explored the mechanism of preferential survival.Methods: Flow cytometry identified surface markers and cytokines produced from accumulated Tscm in the presence of the glycogen synthase kinase beta inhibitor TWS119. Apoptosis was evaluated after induction using tumor necrosis factor-alpha.Immunofluorescence and Western blot analyses were used to investigate the activation of the nuclear factor-kappa B(NF-КB)pathway.Results: RCC patients had a similar percentage of CD4^+ and CD8^+ Tscm as healthy donors. Activation of Wnt signaling by TWS119 resulted in the accumulation of Tscm in activated T cells, but reversal of differentiated T cells to Tscm was not achieved.Preferential survival of Tscm was associated with increased anti-apoptotic ability mediated downstream of the NF-КB activation pathway.Conclusions: The finding that Tscm can accumulate by Wnt signaling in vitro in blood from RCC patients will help in devising new cancer therapy strategies of Tscm-based adoptive immunotherapy, such as dendritic cell-stimulated Tscm, and T cell receptor or chimeric antigen receptor-engineered Tscm.

Recent Progress of Electrode Materials for Flexible Perovskite Solar Cells

Flexible perovskite solar cells(FPSCs) have attracted enormous interest in wearable and portable electronics due to their high power-per-weight and low cost. Flexible and efficient perovskite solar cells require the development of flexible electrodes compatible with the optoelectronic properties of perovskite. In this review, the recent progress of flexible electrodes used in FPSCs is comprehensively reviewed. The major features of flexible transparent electrodes, including transparent conductive oxides, conductive polymer, carbon nanomaterials and nanostructured metallic materials are systematically compared. And the corresponding modification strategies and device performance are summarized. Moreover, flexible opaque electrodes including metal films, opaque carbon materials and metal foils are critically assessed. Finally, the development directions and difficulties of flexible electrodes are given.

Methyl jasmonate mediates melatonin-induced cold tolerance of grafted watermelon plants

Root–shoot communication has a critical role in plant adaptation to environmental stress.Grafting is widely applied to enhance the abiotic stress tolerance of many horticultural crop species;however,the signal transduction mechanism involved in this tolerance remains unknown.Here,we show that pumpkin-or figleaf gourd rootstock-enhanced cold tolerance of watermelon shoots is accompanied by increases in the accumulation of melatonin,methyl jasmonate(MeJA),and hydrogen peroxide(H_(2)O_(2)).Increased melatonin levels in leaves were associated with both increased melatonin in rootstocks and MeJA-induced melatonin biosynthesis in leaves of plants under cold stress.Exogenous melatonin increased the accumulation of MeJA and H_(2)O_(2) and enhanced cold tolerance,while inhibition of melatonin accumulation attenuated rootstock-induced MeJA and H_(2)O_(2) accumulation and cold tolerance.MeJA application induced H_(2)O_(2) accumulation and cold tolerance,but inhibition of JA biosynthesis abolished rootstock-or melatonin-induced H_(2)O_(2) accumulation and cold tolerance.Additionally,inhibition of H_(2)O_(2) production attenuated MeJA-induced tolerance to cold stress.Taken together,our results suggest that melatonin is involved in grafting-induced cold tolerance by inducing the accumulation of MeJA and H_(2)O_(2).MeJA subsequently increases melatonin accumulation,forming a self-amplifying feedback loop that leads to increased H_(2)O_(2) accumulation and cold tolerance.This study reveals a novel regulatory mechanism of rootstock-induced cold tolerance.

Disruption of the bHLH transcription factor Abnormal Tapetum 1 causes male sterility in watermelon

Although male sterility has been identified as a useful trait for hybrid vigor utilization and hybrid seed production,its underlying molecular mechanisms in Cucurbitaceae species are still largely unclear.Here,a spontaneous male-sterile watermelon mutant,Se18,was reported to have abnormal tapetum development,which resulted in completely aborted pollen grains.Map-based cloning demonstrated that the causal gene Citrullus lanatus Abnormal Tapetum 1(ClATM1)encodes a basic helix-loop-helix(bHLH)transcription factor with a 10-bp deletion and produces a truncated protein without the bHLH interaction and functional(BIF)domain in Se18 plants.qRT–PCR and RNA in situ hybridization showed that ClATM1 is specifically expressed in the tapetum layer and in microsporocytes during stages 6–8a of anther development.The genetic function of ClATM1 in regulating anther development was verified by CRISPR/Cas9-mediated mutagenesis.Moreover,ClATM1 was significantly downregulated in the Se18 mutant,displaying a clear dose effect at the transcriptional level.Subsequent dual-luciferase reporter,β-glucuronidase(GUS)activity,and yeast one-hybrid assays indicated that ClATM1 could activate its own transcriptional expression through promoter binding.Collectively,ClATM1 is the first male sterility gene cloned from watermelon,and its self-regulatory activity provides new insights into the molecular mechanism underlying anther development in plants.

The role of watermelon caffeic acid O-methyltransferase (ClCOMT1) in melatonin biosynthesis and abiotic stress tolerance

Melatonin is a pleiotropic signaling molecule that regulates plant growth and responses to various abiotic stresses.The last step of melatonin synthesis in plants can be catalyzed by caffeic acid O-methyltransferase(COMT),a multifunctional enzyme reported to have N-acetylserotonin O-methyltransferase(ASMT)activity;however,the ASMT activity of COMT has not yet been characterized in nonmodel plants such as watermelon(Citrullus lanatus).Here,a total of 16 putative O-methyltransferase(ClOMT)genes were identified in watermelon.Among them,ClOMT03(Cla97C07G144540)was considered a potential COMT gene(renamed ClCOMT1)based on its high identities(60.00–74.93%)to known COMT genes involved in melatonin biosynthesis,expression in almost all tissues,and upregulation under abiotic stresses.The ClCOMT1 protein was localized in the cytoplasm.Overexpression of ClCOMT1 significantly increased melatonin contents,while ClCOMT1 knockout using the CRISPR/Cas-9 system decreased melatonin contents in watermelon calli.These results suggest that ClCOMT1 plays an essential role in melatonin biosynthesis in watermelon.In addition,ClCOMT1 expression in watermelon was upregulated by cold,drought,and salt stress,accompanied by increases in melatonin contents.Overexpression of ClCOMT1 enhanced transgenic Arabidopsis tolerance against such abiotic stresses,indicating that ClCOMT1 is a positive regulator of plant tolerance to abiotic stresses.

Secondary crystallization strategy for highly efficient inorganic CsPbI_(2)Br perovskite solar cells with efficiency approaching 17%

Inorganic CsPbI_(2) Br perovskite solar cells(PSCs) have a tremendous development in last few years due to the trade-off between the excellent optoelectronic properties and the relatively outstanding stability.Herein,we demonstrated a strategy of secondary crystallization(SC) for CsPbI_(2) Br film in a facile planar n-i-p structure(ITO/ZnO-SnO_(2)/CsPbI_(2) Br/Spiro-OMeTAD/Ag) at low-temperature(150℃).It is achieved through the method of post-treatment with guanidinium bromine(GABr) atop annealed CsPbI_(2) Br film.It was found that the secondary crystallization by GABr can not only regulate the crystal growth and passivate defects,but also serve as a charge collection center to effectively collect photogenerated carriers.In addition,due to the excess Br ions in GABr,the formation of the Br-rich region at the CsPbI_(2) Br perovskite surface can further lower the Fermi level,leading to more beneficial band alignment between the perovskite and the hole transport layer(HTL),while the phase stability was also improved.As a result,the champion cell shows a superb open-circuit voltage(V_(oc)) of 1.31 V,a satisfactory power conversion efficiency(PCE) of 16.97% and outstanding stabilities.As far as we know,this should be one of the highest PCEs reported among all-inorganic CsPbI_(2) Br based PSCs.

Defects and doping engineering towards high performance lead-free or lead-less perovskite solar cells

Up to now, perovskite solar cells(PSCs) have reached a certified 25.5% efficiency. As a promising photo-electric material, the metal halide perovskite possesses many outstanding properties such as tunable bandgap, long diffusion length, high absorption coefficient and carrier mobility. In spite of these remarkable properties, defects are inevitable during the solution processing. Therefore, many efforts have been made to reduce defects in perovskite films and thus improve the performance of devices. Among them,substitution or doping engineering is one of the most studied methods. Meanwhile, due to the poor stability of the organic-inorganic hybrid perovskite and the toxicity of Pb-based perovskite materials, all inorganic perovskite and lead-less or lead-free perovskite have emerged as promising materials. Here,we focus on the defect engineering especially substitutions on different sites in an ABX_(3) structure. The particular attention is devoted towards lead-less or lead-free perovskites, and we discuss several common elements or groups used to partially replace Pb^(2+). It is noted that proper elemental doping at different sites is an important guarantee for obtaining high-performance lead-less or lead-free PSCs.

Reveal the large open-circuit voltage deficit of all-inorganic CsPbIBr_(2) perovskite solar cells

Due to excellent thermal stability and optoelectronic properties, all-inorganic perovskite is one of the promising candidates to solve the thermal decomposition problem of conventional organic–inorganic hybrid perovskite solar cells(PSCs),but the larger voltage loss(V_(loss)) cannot be ignored, especially CsPbIBr_(2), which limits the improvement of efficiency. To reduce V_(loss), one promising solution is the modification of the energy level alignment between the perovskite layer and adjacent charge transport layer(CTL), which can facilitate charge extraction and reduce carrier recombination rate at the perovskite/CTL interface. Therefore, the key issues of minimum V_(loss) and high efficiency of CsPbIBr_(2)-based PSCs were studied in terms of the perovskite layer thickness, the effects of band offset of the CTL/perovskite layer, the doping concentration of the CTL, and the electrode work function in this study based on device simulations. The open-circuit voltage(V_(oc)) is increased from 1.37 V to 1.52 V by replacing SnO_(2) with ZnO as the electron transport layer(ETL) due to more matching conduction band with the CsPbIBr;layer.

Double Side Interfacial Optimization for Low-Temperature Stable CsPbI_(2)Br Perovskite Solar Cells with High Efficiency Beyond 16%

CsPbI_(2)Br perovskite solar cells have achieved rapid development owing to their exceptional optoelectronic properties and relatively outstanding stability.However,open-circuit voltage(Voc)loss caused by band mismatch and charge recombination between perovskite and charge transporting layer is one of the crucial obstacles to further improve the device performance.Here,we proposed a bilayer electron transport layer ZnO(bottom)/SnO_(2)(top)to reduce the Voc loss(Eloss)and promote device Voc by ZnO insert layer thickness modulation,which could improve the efficiency of charge carrier extraction/transfer and suppress the charge carrier recombination.In addition,guanidinium iodide top surface treatment is used to further reduce the trap density,stabilize the perovskite film and align the energy levels,which promotes the fill factor,short-circuit current density(Jsc),and stability of the device.As a result,the champion cell of double-side optimized CsPbI_(2)Br perovskite solar cells exhibits an extraordinary efficiency of 16.25%with the best Voc as high as 1.27 V and excellent thermal and storage stability.

Multifunctional solar-blind ultraviolet photodetectors based on p-PCDTBT/n-Ga_(2)O_(3)heterojunction with high photoresponse

Solar-blind ultraviolet(UV)photodetectors based on p-organic/n-Ga_(2)O_(3) hybrid heterojunctions have attracted extensive attention recently.Herein,the multifunctional solar-blind photodetector based on p-type poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20,10,30-benzothiadiazole)](PCDTBT)/n-type amorphous Ga_(2)O_(3)(a-Ga_(2)O_(3))is fabricated and investigated,which can work in the phototransistor mode coupling with self-powered mode.With the introduction of PCDTBT,the dark current of such the a-Ga_(2)O_(3)-based photodetector is decreased to 0.48 pA.Meanwhile,the photoresponse parameters of the a-Ga_(2)O_(3)-based photodetector in the phototransistor mode to solar-blind UV light are further increased,that is,responsivity(R),photo-detectivity(D*),and external quantum efficiency(EQE)enhanced to 187 A W^(-1),1.3×10^(16) Jones and 9.1×10^(4)% under the weak light intensity of 11μW cm^(-2),respectively.Thanks to the formation of the built-in field in the p-PCDTBT/n-Ga_(2)O_(3) type-Ⅱ heterojunction,the PCDTBT/Ga_(2)O_(3) multifunctional photodetector shows self-powered behavior.The responsivity of p-PCDTBT/n-Ga_(2)O_(3) multifunctional photodetector is 57.5 mA W^(-1) at zero bias.Such multifunctional p-n hybrid heterojunction-based photodetectors set the stage for realizing high-performance amorphous Ga_(2)O_(3) heterojunction-based photodetectors.

Solution-Processed Hybrid Europium (Ⅱ) lodide Scintillator for Sensitive X-Ray Detection

Lead halide perovskite nanocrystals have recently demonstrated great potential as x-ray scintillators,yet they stll suffer toxicity issues,inferior light yield(LY)caused by severe self-absorption.Nontoxic bivalent europium ions(Eu^(2+))with intrinsically efficient and self-absorption-free d-f transition are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated solution-processed organic-inorganic hybrid halide BA_(10)Eul_(12)(BA denotes C_(4)H_(9)NH_(4)^(+))single crystals for the first time.

用于神经形态学计算的低能耗、高稳定性2D-3D钙钛矿忆阻器

近年来,有机-无机卤化物钙钛矿在忆阻器和人工突触器件等电子器件中的应用取得了快速进展.由于其离子迁移特性和制造上的优势,有机-无机卤化物钙钛矿有望成为下一代计算设备的候选材料.本文采用ITO/FA_(1-y)MA_(y)PbI_(3-x)Cl_(x)/(PEA)_(2)PbI_(4)/Au的叠层结构,研究了2D-3D有机-无机杂化钙钛矿忆阻器.结果表明,这种新型忆阻器具有新颖的电阻开关特性,如扫描速率相关的电流开关特性、良好的电流-电压曲线重复性和超低能耗.利用p-i-n结模型证实了缺陷调制电子隧穿机制,并证明了忆阻器件的电导状态由电极侧附近钙钛矿薄膜中的缺陷浓度决定.除了良好的忆阻特性外,这种2D-3D钙钛矿型忆阻器还可以很好地用作人工突触,其内部缺陷运动可以真实地模拟生物突触中Ca^(2+)的流入和挤出.此外,由于有机-无机卤化物钙钛矿中的可切换p-i-n结构,这种基于钙钛矿的人工突触具有超低功耗.我们的发现展示了2D-3D钙钛矿忆阻器在未来神经形态计算系统中的巨大应用潜力.

Flexible double-wall carbon foam/Cu-Co oxides based symmetric supercapacitor with ultrahigh energy density

Electrochemical supercapacitors are regarded as a promising electrochemical energy storage device,because of its fast chargeability,long cycle life,and high power density.The connection of porous carbon and extensive electroactive substances have significantly improved their performance.However,the unsuitable constructing strategy and unclear electrochemical mechanism lead to a mismatch between the fast double-layer effect and the sluggish Faradaic behavior at the electrode,degrading the energy density and capacitance performances.Herein,the construction strategy based on the double-wall carbon foam,carbon nanotubes and copper nanocubes provides enhanced electronic structure and ion transport path,resulting in accelerated proton transport and redox insertion/deinsertion processes,as well as surprising electrochemical behaviors of Cu-Co oxide on both positive and negative electrodes(927.9 and 427.0 F g^(−1)at 1 A g^(−1)).A flexible symmetric supercapacitor assembled with the SCF/CNT@Cu/Cu-Co-O delivers a extremely excellent performance.At 1 A g^(−1),the specific capacitance is 337.8 F g^(−1),the energy density hits 60 Wh kg^(−1)at the power density of 17.8 kW kg^(−1).At 10 A g^(−1),the energy density is up to 120.1 Wh kg^(−1),representing the top energy density of supercapacitors.Combining systematical structural optimization and mechanism study,this work broadens the fabricating strategy of hierarchical nanostructures and high-performance electrode materials for energy storage.

Recent advances of carbon nanotubes in perovskite solar cells

Perovskite solar cells(PSCs)have exhibited tremendous potential in photovoltaic fields owing to their appreciable performance and simple fabrication.Nevertheless,device performances are still required to be further improved before commercial applications.As one-dimensional materials,carbon nanotubes(CNTs)have been utilized to regulate stability and efficiency of PSCs because of their excellent chemical stability,flexibility,as well as tunable optical and electrical characteristics.In this review,we comprehensively summarize various functions of CNTs in PSCs,such as transparent electrodes,hole/electron-transport layers,counter electrodes,perovskite additives,and interlayers.Additionally,applications of CNTs toward the advancement of flexible and semitransparent PSCs are provided.Finally,we preview the challenges and research interests of using CNTs in high-efficiency and stable perovskite devices.

Low Trap Density Para-F Substituted 2D PEA_(2)PbI_(4)(X=Cl,Br,I)Single Crystals with Tunable Optoelectrical Properties and High Sensitive X-Ray Detector Performance

Exploring halogen engineering is of great significance for reducing the density of defect states in crystals of organic-inorganic hybrid perovskites and hence improving the crystal quality.Herein,high-quality single crystals of PEA_(2)PbI_(4)(X=CI,Br,I)and their para-F(p-F)substitution analogs are prepared using the facile solution method to study the effects of both p-F substitution and halogen anion engineering.After p-F substitution,the triclinic PEA_(2)PbX_(4)(X=Cl,Br)and cubic PEA_(2)PbX_(4)(X=I)crystals unifies to monoclinic crystal structure for p-F-PEA_(2)PbX_(4)(X=Cl,Br,I)crystals.The p-F substitution and halogen engineering,together with crystal structure variation,enable the tunability of optoelectrical properties.Experimentally,after the p-F substitution,the energy levels are lowered with increased Fermi levels,and the bandgaps of p-F-PEA_(2)PbX_(4)(X=Cl,Br,I)are slightly reduced.Beneftting from the enhancement of the charge transfer and the reduced trap density by p-F substitution and halogen anion engineering,the average carrier lifetime of the p-F-PEA_(2)PbI_(4)is obviously reduced.Compared with PEA_(2)PbI_(4)the X-ray detector based on p-F-PEA_(2)PbI_(4)single crystals exhibits higher radiation stability under high-dose X-ray irradiation,implying long-term operando stability.

Hf_(0.5)Zr_(0.5)O_(2)基铁电忆阻器的多级存储潜力以及人工突触可塑性

忆阻器能够模拟人脑兼具存储和计算的功能,从而突破冯·诺依曼框架.然而,传统忆阻器内部导电细丝的形成和断裂是不稳定的,因此难以真实地模仿生物突触的功能,这个问题已成为阻碍忆阻器模拟神经突触应用的主要因素.铁电忆阻器克服了传统忆阻器的缺点,因为它的电阻变化取决于铁电薄膜的极化翻转.本工作中,我们提出了一种具有Au/Hf0.5Zr0.5O2/p^+-Si结构的铁电忆阻器,能够实现电阻开关特性.重要的是,该器件能够实现多级存储的稳定特性,具有应用于多级存储的潜力.同时通过调控铁电极化,忆阻器的电阻可由铁电畴的翻转来逐步调节.同时,我们可以获取具有双向连续可逆性的多个电阻状态,这类似于神经突触权重的变化.我们还成功模拟了生物学突触功能,例如长期抑制,长期促进,双脉冲易化和尖峰时间依赖可塑性.因此,该器件是一种有希望突破冯·诺依曼框架的候选者.