Undercoordinated Pb2+ defects passivation via tetramethoxysilane-modified for efficient and stable perovskite solar cells

Organic-inorganic hybrid perovskite solar cells (PSCs) have developed rapidly in recent years, and the instability limits its commercialization. Non-radiative recombination caused by defects and water stability affect the device stability. Here we introduce an organic silane additive, tetramethoxysilane (TMOS), which can reduce the non-radiative recombination and prevent the water erosion. The methoxy group in TMOS can combine with Pb²⁺ of perovskite to passivate undercoordinated Pb²⁺ defects and reduce non-radiative recombination. Under a certain humidity, the hydrolyzed product SiO₂ can occupy the grain boundary sites to prevent the erosion of water molecules, slow down the degradation of perovskite, and improve the crystal phase stability of perovskite. The PCE of the device increases from 17.13% to 20.12%. After 400 h at 50% relative humidity (RH), the PSC with 2% TMOS can maintain the efficiency of 90%, while the efficiency of the control group quickly dropped to only 70% of the initial.     

The effect of partial substitution of Ti with Zr, Cr or V in the Mg35Ti10Ni55 electrode alloy on its electrochemical performance

In this paper, Zr, Cr and V were selected as the partial substitution elements for Ti to form Mg₃₅Ti₅M₅Ni₅₅ quaternary alloys prepared by means of mechanical alloying on the basis of the ternary Mg₃₅Ti₁₀Ni₅₅ electrode alloy previously studied by the authors. It is found that all the three quaternary alloys possess an amorphous main phase and exhibit improved cycling stability than the original ternary Mg₃₅Ti₁₀Ni₅₅. The Zr-substituted alloy has also a higher discharge capacity. X-ray photoelectron spectroscopy (XPS) surface analysis reveals that on the surface of each alloy a multi-component oxide composite film is formed, which is more compact and corrosion resistant than the Mg(OH)₂ film and the (TiO₂)_x(NiO)_y(Mg(OH)₂)_z composite films reported previously. Auger electron spectroscopy (AES) analysis shows that the substituting elements tend to reduce the thickness of the passivation films. The thickness of composite oxide film on the alloys is in the following order: Mg₃₅Ti₁₀Ni₅₅>Mg₃₅Ti₅V₅Ni₅₅>Mg₃₅Ti₅Zr₅Ni₅₅>Mg₃₅Ti₅Cr₅Ni₅₅. The result agrees well with that of the polarization resistances (R_P) values obtained from the electrochemical impedance spectroscopy (EIS) Nyquist diagrams. It demonstrates that the thicker the passivation film is, the higher the R_P is and the more difficultly the charge transfer reaction proceeds. Anodic polarization curves indicate that the addition of Cr and Zr decreases effectively the corrosion current. However, the corrosion of the electrode alloys in the electrolyte is still high and proceeds constantly as the corrosion current remains almost constant during further cycles.     

Encapsulation of organic light-emitting devices by means of photopolymerized polyacrylate films

For encapsulation of organic light-emitting devices (OLEDs) built on glass substrate, photopolymerizable blend consists of pentaerythritol triacrylate (PETIA) and HSP188 (photoinitiator) was spin-coated onto an OLED and then cured to form a cross-linked passivation layer. The electroluminescence (EL) and the rate of degradation were examined to compare the electrical and the emissive properties of the device before and after forming the passivation layer. In this case, wet process encapsulation, which did not influence the EL characteristic of the device, enhanced the lifetime of the device in air.     

Synergistic Effect of Mo,W, Mn and Cr on the Passivation Behavior of a Fe-Based Amorphous Alloy Coating

In this work, the electrochemical behaviors of SAM2 X5 Fe-based amorphous alloy coating and hard chromium coating were comparatively studied in 3.5 wt% Na Cl solution. In comparison with the hard chromium coating, the SAM2 X5 coating exhibited a wider and stable passive region with lower passive current density in the potentiodynamic polarization and showed a considerably lower current density at different anodic potentials in the potentiostatic polarization. In order to understand the passivation mechanism of the Fe-based amorphous coating, the components of the passive films formed at various polarization potentials were examined by X-ray photoelectron spectroscopy. The synergistic effect of Mo, W, Mn and Cr in the passive films was systemically analyzed. It has been revealed that Mo and W facilitate the formation of compact and stable Cr_2O_3 passive film at lower potentials, and the substantial enrichment of Mn in the passive film enhances the passivation ability at relatively higher potentials. The deep understanding of the passivation characteristics in multicomponent alloy systems could provide a guide for the design of corrosion-resistant amorphous alloy coatings for engineering applications.     

铜及铜合金化学抛光及钝化的研究

研究了铜及铜合金化学抛光液及其钝化液的组成和工艺,讨论了抛光液各组分和抛光温度、时间、搅拌方式等工艺条件的影响,介绍了一种铜及铜合金的化学抛光和钝化工艺。     

Technology of passivated surface channel MESFETs with modified gate structures

Surface channel MESFETs have suffered from instabilities and drift in the past. To overcome these effects a suitable device passivation seems to be one of the key aspects. In this investigation such a passivation scheme on the basis of Atomic Layer Deposition (ALD) of Al₂O₃ has been developed and combined with advanced gate structures, like a field plate and a second MOS gate (in a dual gate configuration).     

Improvement of carrier diffusion length in silicon nanowire arrays using atomic layer deposition

To achieve a high-efficiency silicon nanowire (SiNW) solar cell, surface passivation technique is very important because a SiNW array has a large surface area. We successfully prepared by atomic layer deposition (ALD) high-quality aluminum oxide (Al₂O₃) film for passivation on the whole surface of the SiNW arrays. The minority carrier lifetime of the Al₂O₃-depositedSiNW arrays with bulk silicon substrate was improved to 27 μs at the optimum annealing condition. To remove the effect of bulk silicon, the effective diffusion length of minority carriers in the SiNW array was estimated by simple equations and a device simulator. As a result, it was revealed that the effective diffusion length in the SiNW arrays increased from 3.25 to 13.5 μm by depositing Al₂O₃ and post-annealing at 400°C. This improvement of the diffusion length is very important for application to solar cells, and Al₂O₃ deposited by ALD is a promising passivation material for a structure with high aspect ratio such as SiNW arrays.     

Electropolishing and passivation of NiTi shape memory alloy

Electropolishing of NiTi alloy has been investigated. The influence of polishing bath composition and the operating conditions instead of the conditions of the process on the quality of the surface, evaluated by AFM and SEM methods, was established. Morphologically uniform surfaces were obtained only in the case of solutions containing hydrofluoric and sulfuric acids. Electropolished samples were sterilized and thermally passivated, then their corrosion resistance was measured in Tyrode's physiological solution. It was established that already after the electropolishing the corrosion resistance of NiTi alloy increases due to the spontaneously formed TiO₂ layer. The increase of the thickness of the layer during sterilization and thermal passivation causes further increase in the corrosion resistance.     

Atomic emission spectroelectrochemistry applied to dealloying phenomena II. Selective dissolution of iron and chromium during active-passive cycles of an austenitic stainless steel

Atomic emission spectroelectrochemistry was used to investigate selective dissolution of a 304 austenitic stainless steel sample in 2 M H₂SO₄. The partial dissolution rates of Fe, Cr, Ni, Mn, Mo, and Cu were measured as function of time during a series of potentiostatic triggered activation/passivation cycles. When first exposed to sulfuric acid solution, the steel sample was in a passive state with a total steady state ionic dissolution rate expressed as an equivalent current density of 10 μA cm⁻². A transition into the active and passive state could be triggered by cathodic (−700 mV vs. Ag/AgCl) and anodic (+400 to +700 mV vs. Ag/AgCl) potentiostatic pulses respectively of variable time. Excess Cr dissolution was observed during the activation cycle as compared to Fe and a depletion of Cr dissolution was observed during the passivation cycle. These results are interpreted in terms of the dissolution of a Cr rich passive layer during activation and selective dissolution of Fe, Mn, Ni and other elements to form a Cr rich passive layer during passivation. Quantitative analysis of the excess Cr showed that the residual film contained approximately 0.38 μg Cr/cm². Fe does not appear to be incorporated into the film at this early stage of passive film growth. Residual films of metallic nickel and copper were formed on the surface during the active period that subsequently dissolved during passivation.     

黄铜矿细菌浸出机理及钝化原因研究进展

细菌冶金技术由于成本低、污染少、流程短等优点,越来越受到人们重视,由于在常温下黄铜矿的细菌浸出速率较慢,有必要研究提高黄铜矿浸出速率的方法。综述了黄铜矿的细菌浸出机理以及黄铜矿的钝化原因。研究结果表明黄钾铁矾、硫层、中间产物层、高的溶液还原电位和黄铜矿稳定的晶体结构可能是黄铜矿细菌浸出过程中的钝化原因。