Studies of diamond-like carbon (DLC) films deposited on stainless steel substrate with Si/SiC intermediate layers

In this work, diamond-like carbon （DLC） films were deposited on stainless steel substrates with Si/SiC intermediate layers by combining plasma enhanced sputtering physical vapour deposition （PEUMS-PVD） and microwave electron cyclotron resonance plasma enhanced chemical vapour deposition （MW-ECRPECVD） techniques. The influence of substrate negative self-bias voltage and Si target power on the structure and nano-mechanical behaviour of the DLC films were investigated by Raman spectroscopy, nano-indentation, and the film structural morphology by atomic force microscopy （AFM）. With the increase of deposition bias voltage, the G band shifted to higher wave-number and the integrated intensity ratio ID/IG increased. We considered these as evidences for the development of graphitization in the films. As the substrate negative self-bias voltage increased, particle bombardment function was enhanced and the sp^3-bond carbon density reducing, resulted in the peak values of hardness （H） and elastic modulus （E）. Silicon addition promoted the formation of sp^3 bonding and reduced the hardness. The incorporated Si atoms substituted sp^2- bond carbon atoms in ring structures, which promoted the formation of sp^3-bond. The structural transition from C-C to C-Si bonds resulted in relaxation of the residual stress which led to the decrease of internal stress and hardness. The results of AFM indicated that the films was dense and homogeneous, the roughness of the films was decreased due to the increase of substrate negative self-bias voltage and the Si target power.

MoO_3/Ag/Al/ZnO intermediate layer for inverted tandem polymer solar cells

We report an MoO3/Ag/Al/ZnO intermediate layer connecting two identical bulk heterojunction subcells with a poly（3-hexylthiophene） and [6,6]-phenyl-C61-butyric acid methyl ester （P3HT and PCBM） active layer for inverted tan- dem polymer solar cells. The highly transparent intermediate layer with an optimized thickness realizes an Ohmic contact between the two subcells for effective charge extraction and recombination. A maximum power conversion efficiency of 3.76% is obtained for the tandem cell under 100 mW/cm2 illumination, which is larger than that of a single cell （3.15%）. The open-circuit voltage of the tandem cell （1.18 V） approaches double that of the single cell （0.61 V）.

Cycle stability of lithium/garnet/lithium cells with different intermediate layers

The garnet-type electrolytes such as Ta-doped Li7La3Zr2Ol2 （LLZTO） have been viewed as the promising electrolytes for solid-state lithium batteries, but it exhibits problem of high interfacial resistance （1960 Ω·cm^2） and short circuit when being cycled in Li/LLZTO/Li cells at the current density above 0.5 mA·cm^-2. Introduction of intermediate layers in between lithium and LLZTO is helpful for decreasing the interfacial resistance and suppressing the growth of lithium dendrites. In this work, three kinds of intermediate layers of Au, Nb and Si with the thickness of 100 nm were prepared. Although the interfacial resistance with the Au layer decreases from 1960 to 32 Ω·cm^2, the cells can only cycle for 0.67 h at 0.5 mA·cm^-2, related to the Au peeled off from the LLZTO. The Nb layers lead to the initial interfacial resistance of 14 Ω·cm^2, while showing extension of cycle time to 50 h with the increase in interracial resistance due to the formation of the resistive Li-Nb-O phase. The Si layers induce the interfacial resistance as low as 5 Ω·cm^2 and the cycles as long as 120 h, which is attributed to the improvement in electrical contact between Li and electrolyte as well as the maintenance of conductive interface during cycles.

Solution-Processed Titanium Chelate Used as Both Electrode Modification Layer and Intermediate Layer for Efficient Inverted Tandem Polymer Solar Cells

ABSTRACT Organic polymer solar cells （PSCs） have attracted increasing attention due to light weight, low cost, flexibility and roll-to-roll manufacturing. However, the limited light harvest range of the photoactive layer greatly restrains the power conversion efficiency （PCE） enhancement. In order to expand the light absorption range and further enhance the PCE of the PSCs, tandem structures have been designed and demonstrated. In tandem solar cell, the intermediate layer （IML） plays a critical role in physically and electrically connection of the two subcells. Herein, we apply titanium （diisopropoxide） bis（2,4-pentanedionate） （TIPD） as both electrode modification layer and intermediate layer to investigate the feasibility in inverted tandem polymer solar cells. The same photoactive layers of PTB7-Th：PC71BM are adopted in both front and rear subcells to simplify the evaluation of effectiveness of TIPD layer in tandem structures. By modulating the treatment condition of IML and the thickness of photoactive layer, efficient inverted tandem PSCs have been achieved with minimized voltage loss and excellent charge transportation, giving a best Voc of 1.54 V, which is almost two times that of the single bulk heterojunction （BHJ）-PSC （0.78 V） and an enhanced PCE up to 8.11%.

Effect of intermediate layer on the activity and adhesion stability of metal monolith supported LaMn-hexaaluminate catalyst for methane combustion

Al2O3 and La2O3 layers were coated respectively on a FeCrAl alloy foil by a dip-coating technique and used as the second support for the active LaMnAl11O19 hexaaluminate （HA） phase in a metallic monolithic catalyst. A sample without an intermediate layer was employed for comparison. The properties and performances of the catalyst were examined with X-ray diffraction （XRD）, scanning electron microscopy （SEM）, ultrasonic vibration and thermal shock techniques. Methane catalytic combustion was performed to evaluate the activity of the catalyst. The results showed that the activity and adhesion of the HA to the alloy foil could be improved with the introduction of the intermediate layer. Al2O3 provided a strong adhesion, while La2O3 weakened the interaction between the active component and alloy foil. For the activity, the catalysts made with the two different intermediate materials also showed difference.

Enhancing Dehydration Performance of Isopropanol by Introducing Intermediate Layer into Sodium Alginate Nanofibrous Composite Pervaporation Membrane

A novel three-tier composite membrane based on highly porous nanofibrous substrate was demonstrated for efficient iso-propanol dehydration by pervaporation.Here,polyethyleneimine(PEI)modified graphene oxide(GO)sheets were vacuum-assistant assembled onto porous electrospun polyacrylonitrile(PAN)nanofibrous substrate to achieve a smooth,hydrophilic and compact PEI-GO intermediate layer.The introduction of PEI chains endowed GO interlayer with sufficient interaction for bonding adjacent GO nanosheets to enhance stability in water/isopropanol mixture and also with the ascended inter-lamellar space to improve the water-sorption ability due to the abundant active amino groups.Benefiting from PEI-GO layer,a defect-free sodium alginate(SA)skin layer could be facilely manufactured with elaborately controlled thickness as thin as possible in order to reduce mass transfer resistant and enhance permeability maximally.Meanwhile,the interlayer would also contribute to enhance interfacial adhesion to promote the structure integrity of three-tier thin-film nanofibrous composite(TFNC)membrane in pervaporation dehydration process.After fine-tuning of membrane preparation process,the SA/PEI(75)-GO-60/PAN TFNC membrane exhibited competitive pervaporation performance with the permeate flux of 2009 g/m2 h and the separation factor of 1276 operated at 70°C for dehydration of 90 wt%isopropanol solution.The unique three-tier composite membrane structure suggested an effective and facile approach to design novel membrane structure for further improvement of pervaporation performance.

Synthesis of one-dimensional GaN nanorods by Tb intermediate layer with different thicknesses

GaN nanorods were synthesized by magnetron sputtering and ammonification system, and the thickness of Tb intermediate layer was changed to study the effect on GaN nanorods. The resultant was tested by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HRTEM）, and photo- luminescence （PL） spectra. The results show that the thickness of Tb layer has an evident effect on the modality, quality, and luminescence properties of GaN nanorods. PL spectra at room temperature show a very strong emission peak at 368 nm and a weak emission peak at 387 nm, and the intensities of the peak for the produced samples reach the maximum when Tb layer is 20 nm. Finally, the optimal thickness of 20 nm of Tb intermediate layer for synthe- sizing GaN nanostructures is achieved.

Formation of the intermediate semiconductor layer for the Ohmic contact to silicon carbide using Germanium implantation

By formation of an intermediate semiconductor layer （ISL） with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An array of transfer length method （TLM） test patterns is formed on N-wells created by P＋ ion implantation into Si-faced p-type 4H- SiC epilayer. The ISL of nickel-metal Ohmic contacts to n-type 4H-SiC could be formed by using Germanium ion implantation into SiC. The specific contact resistance pc as low as 4.23×10-5Ω·cm2 is achieved after annealing in N2 at 800 ℃ for 3 min, which is much lower than that （〉 900℃） in the typical SiC metallisation process. The sheet resistance Rsh of the implanted layers is 1.5 kΩ/□. The technique for converting photoresist into nanocrystalline graphite is used to protect the SiC surface in the annealing after Ge＋ ion implantations.

Nepheloid layer generation by gas eruption:unexpected experimental results

Knowledge of nepheloid layers is important to improve the understanding of physical,geological,and sedimentary processes from continental shelf to abyssal environments.We had not tried to study the nepheloid layers in a hydrate-associated tank until unexpected results occurred.Tank experimental results show that gas eruptions triggered intermediate nepheloid layers.Thus,we proposed a new mechanism of intermediate nepheloid layer generation by eruptions.The intermediate nepheloid layers were generated in uniform-density fluid,which indicated that stratified fluid is not a necessary condition for intermediate nepheloid layers.Sufficient space for advection and an oblique slope for detachment are the key ingredients for intermediate nepheloid layer generation by eruptions.Our experiments also offer a new experimental evidence for bottom nepheloid layer generation by earthquakes.Given the scale effects of laboratory experiment,it is important to determine whether submarine volcanic eruption or hydrate-associated venting causes intermediate nepheloid layer in the nature.

Interface optimization and defects suppression via Na F introduction enable efficient flexible Sb_(2)Se_(3) thin-film solar cells

Sb_(2)Se_(3) with unique one-dimensional(1D) crystal structure exhibits exceptional deformation tolerance,demonstrating great application potential in flexible devices.However,the power conversion efficiency(PCE) of flexible Sb_(2)Se_(3) photovoltaic devices is temporarily limited by the complicated intrinsic defects and the undesirable contact interfaces.Herein,a high-quality Sb_(2)Se_(3) absorber layer with large crystal grains and benign [hkl] growth orientation can be first prepared on a Mo foil substrate.Then NaF intermediate layer is introduced between Mo and Sb_(2)Se_(3),which can further optimize the growth of Sb_(2)Se_(3)thin film.Moreover,positive Na ion diffusion enables it to dramatically lower barrier height at the back contact interface and passivate harmful defects at both bulk and heterojunction.As a result,the champion substrate structured Mo-foil/Mo/NaF/Sb_(2)Se_(3)/CdS/ITO/Ag flexible thin-film solar cell delivers an obviously higher efficiency of 8.03% and a record open-circuit voltage(V_(OC)) of 0.492 V.This flexible Sb_(2)Se_(3) device also exhibits excellent stability and flexibility to stand large bending radius and multiple bending times,as well as superior weak light photo-response with derived efficiency of 12.60%.This work presents an effective strategy to enhance the flexible Sb_(2)Se_(3) device performance and expand its potential photovoltaic applications.

Back contact interfacial modification mechanism in highly-efficient antimony selenide thin-film solar cells

Antimony selenide(Sb_(2)Se_(3))is a potential photovoltaic(PV)material for next-generation solar cells and has achieved great development in the last several years.The properties of Sb_(2)Se_(3)absorber and back contact influence the PV performances of Sb_(2)Se_(3)solar cells.Hence,optimization of back contact characteristics and absorber orientation are crucial steps in raising the power conversion efficiency(PCE)of Sb_(2)Se_(3)solar cells.In this work,MoO2was introduced as an intermediate layer(IL)in Sb_(2)Se_(3)solar cells,and comparative investigations were conducted.The growth of(211)-oriented Sb_(2)Se_(3)with large grains was facilitated by introducing the MoO2IL with suitable thickness.The MoO2IL substantially lowered the back contact barrier and prevented the formation of voids at the back contact,which reduced the thickness of the MoSe2interface layer,inhibited carrier recombination,and minimized bulk and interfacial defects in devices.Subsequently,significant optimization enhanced the open-circuit voltage(VOC)of solar cells from 0.481 V to 0.487 V,short-circuit current density(JSC)from 23.81 m A/cm^(2)to 29.29 m A/cm^(2),and fill factor from 50.28%to 57.10%,which boosted the PCE from 5.75%to 8.14%.

Over 12%efficient kesterite solar cell via back interface engineering

Kesterite Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)has attracted considerable attention as a non-toxic and earthabundant solar cell material.During selenization of CZTSSe film at high temperature,the reaction between CZTSSe and Mo is one of the main reasons that result in unfavorable absorber and interface quality,which leads to large open circuit voltage deficit(VOC-def)and low fill factor(FF).Herein,a WO_(3)intermediate layer introduced at the back interface can effectually inhibit the unfavorable interface reaction between absorber and back electrode in the preliminary selenization progress;thus high-quality crystals are obtained.Through this back interface engineering,the traditional problems of phase segregation,voids in the absorber and over thick Mo(S,Se)_(2)at the back interface can be well solved,which greatly lessens the recombination in the bulk and at the interface.The increased minority carrier diffusion length,decreased barrier height at back interface contact and reduced deep acceptor defects give rise to systematic improvement in VOCand FF,finally a 12.66%conversion efficiency for CZTSSe solar cell has been achieved.This work provides a simple way to fabricate highly efficient solar cells and promotes a deeper understanding of the function of intermediate layer at back interface in kesterite-based solar cells.

Enginered Interfaces for Adherent Coatings

Two methods used to grow adherent coatings, roughening of the surface for mechanical interlocking and the use of chemically compatible interlayers having intermediate thermal expansion coefficients are analyzed numerically with the aid of phase diagram. Calculations indicate that more roughness and smaller periodicity of the substrate surface will increase the interfacial area and thus enhance the adherence strength of the coating. The phase diagram shows that an intermediate layer with a proper composition gradient from the substrate to the film will relax the thermal stress at the interface effectively.

Nanomechanical and Electrochemical Properties of Diamond-Like Carbon (DLC) Films Deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) Technique

Diamond-like carbon （DLC） films was deposited successfully on stainless steel sub- strates with Si/SiC intermediate layers by combining plasma enhanced unbalanced magnetron sputtering physical vapor deposition （PEUMS-PVD） and microwave electron cyclotron resonance plasma enhanced chemical vapor deposition （MW-ECR PECVD） techniques. The effect of sil- icon dopant on the structure, morphology, nanomechanical properties and electrochemical be- havior of DLC films were investigated by Raman spectroscopy, nano-indentation, atomic force microscopy （AFM） and potentiodynamic method and electrochemical impedance spectroscopy （EIS）. It showed that the incorporated silicon atoms substituted sp2-bonded carbon atoms in the ring structures, promoting the formation of sp3-bonds. The structural transition from C-C to C-Si bonds resulted in the relaxation of the residual stress, leading to the decrease in films hardness. The DLC films with Si/SiC intermediate layers led to significant improvement in the corrosion resistance of the stainless steel substrate due to effective isolation and good chemical inertness of the DLC films.

Optical and Electrical Properties of Hydrogenated Silicon Oxide Thin Films Deposited by PECVD

In this work, n-type amorphous silicon oxide thin films were deposited by RF-PECVD method using a gas mixture of SiH4, CO2, H2, and PHy The deposition rate, refractive index, band gap, crystalline volume fraction, and conductivity of the silicon oxide thin films were determined and analyzed. The film with refractive index of 1.99, band gap of 2.6eV and conductivity of 10-7 S/cm was obtained, which was suitable for the intermediate reflector layer.

Low-Frequency Noise Properties of GaN Schottky Barriers Deposited on Intermediate Temperature Buffer Layers

Flicker noise and deep level transient spectroscopy were used to characterize defect properties of GaN films with different buffer structures. Results indicate improved properties with the use of intermediate temperature buffer layers due to the relaxation of residue strain in the films.

Design and optical performance investigation of all-sprayable ultrablack coating

Although ultrablack surfaces are urgently needed in wide applications owing to their extremely low reflectance over a broadband wavelength,obtaining simultaneously the ultrablackness and mechanical robustness by simple process technique is still a great challenge.Herein,by decoupling different light extinction effects to different layers of coating,we design an ultrablack coating that is all-sprayable in whole process.This coating presents low reflectance over visible–mid-infrared(VIS–MIR)wavelength(av.R≈1%in VIS),low multi-angle scattering(bidirectional reflection distribution function(BRDF)=10-2–10-3 sr-1),together with good substrate adhesion grade and self-cleaning ability,which are superior to most reported sprayable ultrablack surfaces.The light extinction effects of each layer are discussed.This method is also applicable in other material systems.