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.

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.

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.

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.

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.

Spin Coating Epitaxial Films

Epitaxy is usually used to produce high quality crystals with ato-mic perfection. Up to now, many semiconductor crystals of functional materials could be obtained by epitaxial growth techniques, such as molecular beam epitaxy, chemical vapor deposition, and liquid-phase epitaxy. However, these techniques are expensive, sophisticated, and not compatible with large area production. For solution-based deposition of epitaxial films such as hydrothermal processing [1], chemical bath deposition [2-3], and electrodeposition [4-5], specific conditions such as high temperature and pressure, or conducting substrates are commonly needed. Since single crystal epitaxial films have superior electronic and optical properties compared to amorphous and polycrystalline films due to absence of high-angle grain boundaries, searching for simple, rapid and inexpensive technique to grow epitaxial films is highly desired.

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.

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.

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.

基于全溶液法制备的SnO_(2)/1D-CsAg_(2)I_(3)异质结的高灵敏自驱动可见光盲紫外探测器

低维非铅金属卤化物材料因其优异的光电特性在可见光盲紫外探测领域具有很大的潜力.本文通过吡啶添加剂辅助一步溶液法成功制备了高质量类钙钛矿CsAg_(2)I_(3)薄膜,该薄膜展示出p型及202 meV低激子结合能(Eb).其Eb甚至和2D铅卤钙钛矿相当,有利于光生载流子分离.此外,探索了基于type-Ⅱ型n-p异质结SnO_(2)/CsAg_(2)I_(3)的自驱动紫外探测器,其中4.13 eV宽带隙、0.214 eV低Urbach能量的SnO_(2)的引入抑制了持续光电导效应.所制备的探测器件具有高灵敏特性及在可见光盲紫外探测器中超快的响应时间(47/74μs),大致快于当前CsAg_(2)I_(3)探测器数值的两个数量级.其响应度和探测率分别高达0.032 A W^(-1)和1.2×10^(11)Jones.此外,异质结>90%高可见光透光性展现出优越的可见光盲特性.这种优异的器件性能、可溶液法制备及长期稳定性为未来可见光盲、自驱动、稳定、环保的商用紫外探测器的制备提供了新思路.

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.

Recent advances in resistive random access memory based on lead halide perovskite

Lead halide perovskites have attracted increasing attention in photovoltaic devices,light-emitting diodes,photodetectors,and other fields due to their excellent properties.Besides optoelectronic devices,growing numbers of studies have focused on the perovskite-based electrical devices in the past few years,such as transistors and resistive random access memories(RRAMs).Here,this article summarizes the recent progress the researchers have made of RRAM devices.Primarily,the working mechanism and the key parameters of RRAM are introduced.Generally,the working principles,including the conductive filament model(containing the types of the model of the metal cationsinduced filament and the model of the ions migration in bulk),the interface effect,and the electronic effect are the origins of the RRAM behaviors,and hence,various factors that affect the device performance are explored.Then,RRAMs based on organolead halide perovskite and all-inorganic perovskite are discussed in terms of different structures,different compositions,and different fabrication methods.Finally,a brief conclusion and a broad outlook are given on the progress and challenges in the field of perovskite-based RRAMs.

Synergistic Interface Layer Optimization and Surface Passivation with Fluorocarbon Molecules toward Efficient and Stable Inverted Planar Perovskite Solar Cells

Large-size organic halide passivation has been considered an efficient approach to enhance the perovskite solar cell(PSC)efficiency and stability.Herein,a facile posttreatment strategy was demonstrated,wherein trifluoromethyl-phenethylamine hydrobromide(CF_(3)-PEABr)is firstly used to passivate the perovskite film surface.The CF_(3)-PEABr surface posttreatment could coordinate with halide dangling bonds that exist at the perovskite crystal surface.Moreover,the surface treatment with CF_(3)-PEABr could efficiently passivate the defects in the perovskite film and suppress the nonradiative carrier recombination.As a result,a high efficiency of 21.3%is obtained,and an increment of 80 mV in V_(oc)(a large V_(oc)of 1.15 V,with a 0.42 V voltage deficit)occurs,compared to the control device.To relieve the hydrophobic nature properties of the-CF_(3)functional group and the dewetting problem of PCBM layer deposition,a surfactant Triton X-100 is used to modify the PCBM layer.Furthermore,the devices with CF_(3)-PEABr posttreatment exhibit better operational,thermal(85℃),and long storage stabilities without any encapsulation.