With the rapid advances of the electronics industry and energy science, thermal management has grown as a key issue to be addressed in multiple areas, including microelectronics, thermal logic devices and thermoelectric technologies. Especially in the semiconductor industry, the demand for thermal dissipation of the chips with ever growing power densities goes far beyond the capability even for the cutting-edge thermal management technologies, which turns out to be a bottleneck for further developments. Such issues call for more comprehensive understandings about thermal transport mechanisms, with extended research focuses on macroscale to microscale. In this review, we take the microstructures into account of thermal transport mechanisms, with the perspectives of diffusive and ballistic thermal transports. Various strategies are thus raised to engineer the thermal transport in the microstructures, as proved to be effective. In this review, focuses are set on point defect, quantum dot, superlattice and especially on interface engineering, in which the intrinsic thermal transport mechanisms are studied as well. With recent research progresses as a reference, it is evident that the rich synthetic material microstructures offer opportunities to strategies on thermal transport engineering. In spite of the challenges from complex device structures, corresponding explorations and studies are further needed.

The energy band characteristic of two-dimensional ternary lattice tungsten-silicone rubber phononic crystals was analyzed by both the plane wave expansion method and finite element method. The propagation characteristics of elastic wave in a silicone rubber plate were analyzed, which were embedded with periodically arranged cylindrical tungsten blocks of the same pore size. Moreover, the special phenomena in the band structure were also discussed, such as the Dirac point and the degeneracy near the Dirac point and so on. The three-dimensional energy band diagram and the main deformation under different modes were given. It is found that stress concentration easily occur in the combination part of the periodic composite material. Then the influence of different material parameters on the bandgap were studied and the initial frequency of the first complete bandgap gradually increases with the increase of the density ratio (the ratio of the scatterer density to the matrix density). However, the bandwidth decreases gradually since the cutoff frequency changes little. Compared with Young's modulus, density has more influence on the bandgap of the periodic composite material. The results of this paper could provide some theoretical guidance for practical engineering application.

The copper thiocyanate (CuSCN) is an inorganic hole transport material with wide-bandgap low cost, high carrier mobility, good stability and excellent light transmittance which has great potential for hole transport layer. However, the current power conversion efficiency (PCE) of the n-i-p type perovskite solar cell (PSCs) based on CuSCN is much lower than that based on spiro-OMeTAD. The main reason is that the PSCs with low open-circuit voltage. It is found that the band gap of the perovskite absorber layer has a great impact on open-circuit voltage of PSCs. PSCs with different band gap 1.55 eV, 1.60 eV and 1.65 eV were fabricated, the PCE of devices based on CuSCN are 12.8%, 14.4% and 10.7%, respectively (The PCE of devices based on Spiro are 20.8%, 19.1% and 17.5%, respectively). The PSCs with a band gap of 1.60 eV form a better energy level alignment with CuSCN and the device with open-circuit voltage of 1.06 V can be achieved. The PCE of champion device is 14.4%. What’s more, when PSCs are exposed to the air with a relative humidity (RH) of 30% to 40%, the unencapsulated PSCs based on CuSCN maintains 92.4% of its initial power conversion efficiency (PCE) at 120 ℃ for 1 h. In a contrast, the device based on spiro-OMeTAD only matains 49.7% of its initial efficiency. It demonstrated that PSCs based on CuSCN with good thermal stability in n-i-p structure devices, which is an ideal hole transport material for stable devices.

Based on the Transverse Ising Model, the solution of the duration equation is derived using the Mean-Field approximation theory. The effects of exchange interactions on the surface of the system and the internal and external transverse field parameters on the ferroelectric-paraelectric phase transition were studied for single and double surface ferroelectric films with different total layers. The effects of various exchange interactions and transverse field parameters of ferroelectric thin films on the phase diagrams of single and double surface ferroelectric thin films were discussed. The results show the total number of thin films layers n, the number of surface layers, internal and external transverse fields, and surface exchange interactions will change the phase diagram of ferroelectric thin films. Using the size effect and surface effect of the film, increasing the total number of layers, surface layers and surface exchange interactions of the system can increase the phase transition temperature of the films and expand the ferroelectric phase area, which is conducive to improving the ambient temperature of the ferroelectric functional device.

The precursor solution was prepared by using zirconium oxychloride octahydrate (ZrOCl2?8H2O) as the raw material, and the ZrO2 film was prepared by spin coating process and then processed via reduction and nitridation. The film structure, optical properties and SERS effect were tested by XRD, FE-SEM, UV-Vis-Nir and Raman. The results show that nitrogen oxides appeare in the film via reduction and nitridation, the particles are obvious, and the thickness of the film is about 0.77 μm. There is a strong absorption peak near 350 nm to 650 nm in the ultraviolet-visible-near-infrared spectrum of the film. The SERS effect of the film was studied using R6G as a probe molecule, the results show that the SERS effect of the zirconia film is significantly improved via reduction and nitridation, and the Raman enhancement factor is 2.479×102.

CaMoO4∶Ho3+ phosphors were synthesized by sol-gel method. The samples were characterized by X-ray powder diffractometer, fluorescence spectrometer and were refined by Rietveld method. The effects of the concentration of Ho3+ on the luminescence properties were studied and the color coordinates of CaMoO4∶Ho3+ were calculated. The results show that the optimal concentration of Ho3+ is 2%(mole fraction). The concentration quenching mechanism is verified to be electric dipole-electric dipole interaction. The color coordinates range of phosphors of this series: x is 0.298 7 to 0.317 7, and y is 0.664 4 to 0.689 7, which belongs to green light-emitting area. CaMoO4∶Ho3+ could be efficiently excited by 450 nm, which is a potential green phosphor for white LED.

Molybdate-based phosphor sample Sr0.7Ca0.16MoO4∶0.07Eu3+0.07A+(A=Na+,K+,Li+) was prepared by high-temperature solid-phase method. The phosphor samples were investigated by XRD and fluorescence spectra. The sample Sr0.7Ca0.16MoO4∶0.07Eu3+0.07A+(A=Na+, K+, Li+) was sintered at 900 ℃ for 8 h. With 615 nm as the monitoring wavelength, in the excitation peak at 330-540 nm, the peak groups at 394 nm and 464 nm belong to Eu3+ transitions of 7F0→5D6 and 7F0→5D2, respectively. Under the excitation of 394 nm and 464 nm, the main peak in the emission spectrum of Sr0.7Ca0.16MoO4∶0.07Eu3+0.07A+(A=Na+, K+, Li+) is located at 615 nm, which is the Eu3+ transition of 5D0→7F2 energy level. The calculated CIE (Commission International del, Eclairage) color coordinates formed by the red light emission, close to the standard values (x=0.670, y=0.330) of the National Television System Committee. In summary, Sr0.7Ca0.16MoO4∶0.07Eu3+0.07A+(A=Na+, K+, Li+) is a red phosphor with good performance and can be used in white LEDs.

SrAl2Si2O8∶Eu2+(SASO∶Eu2+) series phosphors were prepared by high temperature solid-state method. The crystal structure, excitation spectrum, emission spectrum and thermal stability of phosphors were studied in detail. The results show that under 337 nm excitation, the emission spectrum is an asymmetric broadband single peak with a peak wavelength of 404 nm, a peak half-height width of about 53 nm, and the optimal doping molar concentration of Eu2+ is 5%. According to Dexter theory, it is discussed that the quenching of SASO∶Eu2+ phosphor concentration is caused by the interaction between Eu2+electric dipole to dipole. When heated to 225 ℃, the intensity of SASO∶0.05Eu2+ phosphor still has 97.4% of the intensity at the initial room temperature, indicating that it has excellent thermal stability.

In order to study the passivation characteristics of the carrier selective contact structure in N-type crystalline silicon cells, a special material structure was designed. The change of implied open circuit voltage after annealing, deposition of SiNx∶H film and sintering of the materials structure with different doping concentration distribution were compared and the passivation mechanism was analyzed. The results show that the implied open circuit voltage is very sensitive to the doping concentration distribution of structure. The ‘penetrating diffusion’ increase across poly-Si/SiOx into the c-Si base, the corresponding implied open circuit voltage increases firstly and decreases later after annealing, SiNx∶H film deposition and sintering. After the samples were deposited with SiNx∶H thin film, the increase of the implied open circuit voltage gradually decreases; and the value of implied open circuit voltage samples show a tends to decline after sintering, and the declining trend of the implied open circuit voltage gradually decreases. When a suitable doping process is selected, the average value of the implied open circuit voltage can reach 738 mV after firing.

In order to achieve the optimal back passivation effect of monocrystal PERC cell and find out the optimal process conditions, the main process parameters were optimized by orthogonal experimental method. After being passivated by back passivation, the thickness and refractive index of the film and the conversion efficiency of the cell were measured. The results of orthogonal experiments show that the optimal process conditions of back passivation are 0.25 mbar chamber pressure, 360 ℃ temperature setting, 2.8 NH3/SiH4 ratio, 1 500 W microwave power. Under this conditions, the average test efficiency of the cell reaches 22.35%, and the electrical performance indexes such as Voc and Isc reach a high level.

The purpose of this paper is to study the removal process of poly silicon surround coating on the front edge of wafer. And, this layer is formed when poly-si passivation layer of TOPCon (tunnel oxide activated contact) solar cell is deposited on the back. The research solved the problem of bad appearance and poor light absorption of solar cell. In this paper, HF-HNO3 solution and KOH solution were used to corrosion this layer, and then the removal effect was evaluated by monitoring the process control points and EL test after corrosion. When HF 1wt% and HNO3 50wt%, the surround coating can be removed after corrosion for more than 4 min, but the square resistance(R□)and boron doping concentration on the front of silicon wafer change greatly after more than 6 min. When KOH 0.1wt% and additive 5vol%， 60 ℃, the coating can be removed after corrosion for more than 2.5 min, and the change of R□.etc is not obvions. Therefore, the former has higher requirements for the preparation of electrode, otherwise it is easy to cause poor ohmic contact of the solar cell. And for the latter, electrode preparation process of solar cell is easier to control. So, it is the better selection to removal the polysilicon surround coating for industrial production by KOH etching.

The effective doping of semiconductor materials can guarantee the successful application of semiconductor devices. Theoretically, the difficulty of doping and the depth of defect level can be predicted by calculating the defect formation energy and charge transition energy level. The defect properties of four potential substitutional n-doping systems (CB, SiB, GeB,SnB,) in two-dimensional (2D) BN were systematically calculated based on density functional theory and combined with two-dimensional charged defect calculation method. The results show that the most stable valence states of CB(SnB) system are +1(-1) and 0 valence, while the most stable valence states of SiB and GeB system are +1, 0 and -1 valence. The corresponding donor ionization energies of CB, SiB and GeB systems are 2.00 eV, 3.57 eV and 4.06 eV, they all show deep level donors, and it is difficult to provide n-type carriers for h-BN. In addition, in p-type doped host h-BN, CB system has negative formation energy and +1 valence, which will seriously reduce the p-type doping efficiency and hole conductivity of h-BN. The results provide a theoretical basis for experimental doping of 2D h-BN.

A multi-layer thin films structure based on the microcavity effect of metal thin film-distributed Bragg reflector (DBR) to enhance light absorption of monolayer tungsten disulfide (WS2) was proposed. Its optical transport characteristics was studied by optical transfer matrix theory. It is found that the microcavity effect of the metal thin film-DBR forms the maximum value of the electric field strength between the cover layer and spacer layer, which effectively promotes the interaction between incident light and the monolayer WS2. As the thickness of the metal layer, spacer layer and cover layer are comprehensively optimized, the light absorption of monolayer WS2 at 612 nm increases by 38 times, up to 78.42%. Furthermore, the influenced of light incident angle, period of the DBR and the refractive index of space layer on the light absorption of monolayer WS2 were discussed. The research results show that changing of the above structural parameters can effectively regulate the absorption peak value of monolayer WS2. The research results provide new ideas for the preparation of high-performance monolayer WS2 photodetectors and other new optoelectronic devices.

The defect formation energy of each system after P doped ZnO was predicted using the BP neural network optimized by the Adam algorithm, the analysis shows that the most easily formed systems are the ZnO∶PZn and ZnO∶PZn (2VZn) systems, otherwise the ZnO∶PO and ZnO∶PZn (1VZn) system, and the photoelectric characteristics of each system on the basis of first principles were studied. The analysis shows that the ZnO∶PZn system is n-type conductive, with a band gap of 0.78 eV, which is larger than the intrinsic system. ZnO∶PZn (2VZn) system is p-type conductive, and the band gap is similar to the intrinsic system. The electrical conductivity is similar to the ZnO∶PZn system, which is much higher than the ZnO∶PZn (1VZn) system, and the reflectivity, absorptivity, light transmittance are better than intrinsic ZnO system.

The flexible SERS substrate with high activity was prepared by electrospinning. The spinning solution was mixed with silver nitrate and polyvinyl alcohol in certain proportion. The nanofiber substrate was prepared by UV irradiation reduction method after spinning. The synthesized nanofiber substrate was characterized by Scanning electron microscopy (SEM), Transmission electron microscope (TEM), Fourier infrared spectroscopy (FT-IR), Raman spectroscopy, UV visible spectroscopy (UV-Vis). Research show that the silver nanoparticles are spherical in shape and less than 10 nm in diameter, distributed in composite fibers. Using rhodamine as probe molecule, the optimal SERS performance of the substrate is obtained, 16wt% of silver nitrate and 3 h of UV irradiation. At the same time, the substrate is applied to the detection of nicotinic acid drugs. The results show that the limit of Raman detection is 10-5 mol ? L-1.

The precursor was precipitated by hydrothermal method on the carbon cloth matrix, and the porous 3D CoP@CC material with arrays of nano-needle structure was prepared by heating the precursor in the atmosphere of Ar and sodium hypophosphiteat at 300-350 ℃. Its phase composition, microstructure and electrocatalytic performances were analyzed. XRD results indicate the sample is CoP with orthorhombic structure; SEM results indicate the diameter for the arrays of nano-needle structure is less than 100 nm and length is about 10 μm. The electrocatalytic performance results show that the 3D CoP@CC as catalytic materials exhibit excellent electrocatalytic hydrogen evolution reaction(HER) property in the 0.5 mol/L solution of H2SO4. The overpotential reaches 124 mV when the current density is 10 mA?cm-2. The slope of Tafel is 84.9 mV/dec, which indicates that the key reaction is Volmer reaction. There are two half circles of the EIS spectrum, which indicates that there should be two time constants. The value of 0.501 9 for CPE2-P indicates that double layer capacity should be produced on the roughly porous surface of the electrode, which is hard for carriers to transit; this also shows that the main resistivity is originating from mass transition and carrier transition.

The nickel-phosphorus alloy was deposited on carbon nanotube fibers (CNTFs) by an electrochemical deposition method. By comparing the electrocatalytic hydrogen evolution performance of carbon nanotube fibers supported nickel-phosphorus alloy (Ni-P/CNTFs) electrodes prepared under different cycles and different ratios of nickel-phosphorus in neutral electrolyte solution, it was found that when the ratio of nickel-phosphorus in the electrodeposited solution is 2∶1 and the cycle number is 50, the sample has the best electrocatalytic hydrogen evolution performance. It could achieve a current density of 10 mA?cm-2 at an overpotential of 138 mV, and the Tafel slope is 83 mV?dec-1, and it also shows good stability. Moreover, the sample could be bent while the catalytic performance remained constant, which expands its field of application.

The iron-titanium solid solution catalyst with Fe3+/Fe2+ molar ratio of 1∶1 and a certain amount of Ti4+ were synthesized by ammonia co-precipitation method. It was compared with the iron titanium catalyst prepared by mechanical mixing grinding method. The effects of different preparation processes on the physicochemical properties and catalytic activity of catalyst were discussed. The physical and chemical properties of the catalyst were characterized by means of XRD, N2 adsorption-desorption, XPS, H2-TPR and NH3-TPD. The results show that the one-step ammonia co-precipitation method and the doping a certain amount of Ti are beneficial to increase the specific surface area of the catalyst, suppress oxide crystallization and crystal phase transformation, make the catalyst grain size smaller, and improve the low-temperature catalytic activity. At the same time, it shows that the catalyst prepared by mechanical mixing grinding is only a simple mechanical mixing between oxide crystals, which does not form a close coupling effect and can not effectively improve the catalytic performance.

A new adsorbent CaCO3/g-C3N4 was successfully synthesized using melamine and calcium carbonate. The structure of CaCO3/g-C3N4 was studied in depth through XRD, FT-IR, SEM, TEM and BET. The experimental results show that CaCO3/g-C3N4 has fast and efficient selective adsorption performance (89.34%) and excellent adsorption capacity (1 209.75 mg/g) for crystal violet (CV). Adsorption kinetics and isotherms show that CaCO3/g-C3N4 adsorption of CV follows the quasi-second-order kinetic model and the Langmuir isotherm, respectively. At the same time, based on the FT-IR and XPS spectra before and after adsorption and experimental conclusions, a reasonable adsorption mechanism was proposed. The synergistic effects of π-π stacking, n-π interaction, and hydrogen bonding are important reasons for the selective adsorption of CV by the CaCO3/g-C3N4.

ZnO is a kind of photocatalytic materials with a broad application prospect, but problems such as high carrier recombination rate limit its further application. Mn doped ZnO powders were prepared by hydrothermal synthesis. The phase composition, pore structure, luminescence property and photocatalytic properties were studied. Results show that when Mn is instead of 0.5% Zn in ZnO, Mn occupies the place of Zn in ZnO lattice. The powders have small particle size and large specific surface area. The carrier recombination is inhibited, the band gap is reduced, and the light response range is broadened. Under the condition of 8 W, 365 nm UV light, the degradation rate and COD removal of Mn0.05Zn0.95O powders over Congo red reach 97.4% and 76.34%, repectively, after 70 min irradiation. Mn0.05Zn0.95O has the best adsorption for rhodamine B, and the best degradation for methylene blue. The degradation rate over Congo red reduces by 6.6% after 4 successive cycles. The results provide technologic support for photocatalytic degradation of organic waste water.

Ce-La@Fe3O4 composite adsorbents were fabricated by hydrothermal method and it was used to remove fluoride from aqueous solution. SEM images show that Ce-La@Fe3O4 adsorbents are square particle with diameter of (1.22±0.35) μm, and a certain extent adhesion are observed after the adsorption fluoride. The pseudo-second-order has been found suitable for describing the kinetics process of the fluoride absorption on Ce-La@Fe3O4 adsorbents while the net rate can thus be sequentially controlled in a multi-stage condition. The fitness of adsorption data by Langmuir model is superior to Freundlich model．The fluoride adsorption capacity would increase obviously when the reactive temperature rises. Ce-La@Fe3O4 adsorbents are magnetic, and are easy to be recovered and reused by ordinary magnets after adsorption fluoride.

Self-assembly of organo phosphonate ligands and transition metal cadmium salt, 1D coordination polymer, namely Cd0.5(5-pncH2)(H2O)1.5 (1) was hydrothermally synthesized and then characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Structure analyses reveal that compound 1 crystallized in the orthorhombic system, space group Pbcm, a=0.693 43(2) nm，b=0.887 153(3) nm, c=4.188 76(15) nm. Compound 1 disclose a 1D chain structure, in which the adjacent CdIIare bridged into one-dimensional zigzag chain by coordination water molecules. In the chain, there is a C-H…π action of adjacent naphthalene ring edges. The adjacent chains form a two-dimensional layered structure through the carboxyl double hydrogen bond from the organic phosphonic acid ligand, and the layers are connected into a three-dimensional supramolecular network framework through the van der Waals interactions. The thermal stability and luminescence behavior of compound 1 were also investigated.

A cobalt complex with a three-dimensional supramolecular structure was synthesized through ionothermal method. Its structure was characterized by elemental analysis, FT-IR spectroscopy, XRD and TG. Single-crystal X-ray diffraction studies reveals that the complex is in the tetragonal system, space group P21/c with a=0.943 37(6) nm, b=1.451 5(7) nm, c=1.185 48(6) nm, β=100.051(5)°, V=1.598 37(15) nm3. The complex is composed of isolated anion Br- and ［Co(DINE)2］2+cation, which are held together through the hydrogen bonds, formed a three-dimensional supramolecular structure. Furthermore, its fluorescence property was also studied.

The molecular formula of basic magnesium sulfate whisker is xMgSO4?yMg(OH)2?zH2O, which is a synthesized inorganic functional material with a certain aspect ratio. As a filler, basic magnesium sulfate whiskers can improve the mechanical properties such as tensile strength of the material, and also play a role of flame retardant. In the NH4+-NH3 buffer system, MgSO4?5Mg(OH)2?3H2O whiskers with length of 10 μm to 30 μm, diameter of 0.05 μm to 0.3 μm, and an aspect ratio of 30 to 150 were prepared in a one-step process at atmospheric pressure. The products were charcaterized by XRD, SEM, TG, TEM, and the influencing factors such as reaction concentration, reaction temperature, reaction time and aging time were studied combination with the characterization results. The first-principle analysis of the formation mechanism shows that the growth habit of basic magnesium sulfate whiskers accord with the dislocation spiral growth mechanism. The buffer system stabilizes the acidity and basicity of the solution and reduces the non-ideality of the reaction solution. It can make the crystals grow under unforced conditions. Basic magnesium sulfate whiskers provide an important reference for further industrial applications and the realization of low-energy-consumption production.

With waste residue of artificial granite as raw materials, calcium formate crystals was synthesized by neutralization method. The effects of the ratio of the mass ratio of artificial granite waste residue to formic acid, the reaction time, the stirring speed, and the reaction temperature on the utilization of artificial granite slag were analyzed and characterized by SEM, XRD and infrared spectrometer. The results show that the optimum technological conditions for the synthesis of calcium formate from artificial granitic waste residue are as follows: the mass ratio of artificial granitic waste residue to formic acid is 1.0∶1.3, the reaction temperature is 50 ℃, the stirring speed is 430 r/min, the reaction time is 50 min, the volume of sulfide precipitator is 0.15 mL, and the removal rate of iron ion is 98.77%, the yield of calcium formate is 94.20% by complex titration and redox titration. The characterization results show that the artificial granite waste residue presents an irregular shape, the surface is relatively smooth; the product presents the shape of polyhedron with an average particle size is 1 μm, indicating that the synthesized product is gradually grown and molded according to a certain crystal form, and the main product is calcium formate crystals combined with infrared spectroscopy and energy spectrum analysis.

Mn4+ doped fluoride luminescent materials show wide application prospects in the fields of improving the color rendering performance of white LED and the color gamut of LCD backlight due to its high efficiency of narrow-band red emission and wide-band blue excitation properties. This review mainly introduces the main preparation methods and effective ways to improve the humidity resistance of Mn4+ doped fluoride red luminescent materials at home and abroad, and makes a prospect for the micromorphology control of materials from the perspective of expanding applications, so as to provide a reference for further research on the application of multi-type optoelectronic devices.

The recent progress in the preparation of silicon nanowires is introduced, the growth pattern of the two different (“top-down” and “bottom-up”) and the preparation methods of different growth mode are reviewed, such as chemical vapor deposition, molecular beam epitaxy, laser ablation, oxide auxiliary growth, the solution method, electron beam lithography, nano-imprinting lithography, and metal auxiliary chemical etching, etc, and the advantages and disadvantages of these preparation methods are discussed, The research status of two typical growth directions (plane and vertical) of silicon nanowires is summarized. In the end, the application of silicon nanowires in electronic devices, sensors, and solar cells is summarized, and the development trend has prospected.

Lithium-sulfur batteries are regarded as one of the most promising secondary battery energy storage systems for the next generation due to the high theoretical specific capacity of 1 675 mAh?g-1 and theoretical energy density of 2 600 Wh?kg-1. However, the shuttle effects of polysulfides, the poor conductivity of active materials, and the volume expansion effect during charging and discharging hindered its further commercialization. To solve above mentioned problems, different materials are introduced to integration with sulfur. Among all the choices of materials, carbon materials have been widely used in cathodes of lithium-sulfur batteries due to the advantages of high surface area, excellent conductivity, chemical stability, and low cost. In this review, the development of several different carbon materials in sulfur/carbon composite cathodes was summarized, the effect of material structure, pore size and surface functionalization of carbon on the electrochemical performance of lithium-sulfur batteries were discussed. And its prospects and development trends were also predicted.