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Metal-Assisted Silicon Chemical Etching Using Self Assembled Sacrificial Nickel Nanoparticles Template for Anti-Reflection Layers in Photovoltaic and Light-Trapping Devices
摘要： Thin film de-wetting is a simple patterning approach that provides a straight forward method for fabricating silicon structures using metal-assisted chemical etching (MacEtch). Currently, this has been mainly demonstrated with gold (Au) or silver (Ag) catalyst for MacEtch and to accomplish this, an extra Au or Ag nanoparticles lift-off step is required. The uncertain success with the lift-off process is potentially a major hindrance to achieve low-cost, large-scale and uniform Si nanostructures. In this work, we report on the use of nickel (Ni) as an alternative sacrificial metal for the de-wetting process. The de-wetting phenomenon of Ni on silicon dioxide is investigated to show that controllable sizes and density are achievable for this material system. A physical model to describe the relationship among Ni film thickness, particle interspacing and density is proposed. Using the Ni nanoparticles as a starting mask template, an improved approach for the large scale fabrication of silicon nanowires without the use of lithography methods is demonstrated. This not only eliminates problems associated with lift-off but also allows for scaling up of such fabrication using the proposed self-assembly approach, which holds great potential in furthering the versatility of the MacEtch technique in anti-reflection surfaces and light-trapping devices applications.
关键词： MacEtch,Nickel nanoparticles,Silicon,MACE,De-wetting,Metal-assisted chemical etching
更新于2025-09-19 17:13:59
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Cation Effects in p-Type Dye Sensitized Solar Cells
摘要： The performance of dye sensitized solar cells (DSSCs) depends on the properties and interactions of three fundamental components: the semiconductor, chromophore, and electrolyte. For the electrolyte, the dependence of DSSC performance on the identity and valence state of the spectator cation has not been well studied in p-type semiconductor systems, although the effects of these species in n-type TiO2 devices are significant, producing large shifts in semiconductor flat band potential, charge transfer kinetics, photocurrent, and open-circuit voltage (VOC). Here, we vary the spectator cation in p-type NiO DSSCs and demonstrate an increase in VOC by over 50% with two common redox couples. Using optimal cations, high VOC values are achieved without a significant reduction in photocurrent. Mott-Schottky analysis and electrochemical impedance spectroscopy reveal that the cation can shift the flat-band potential of NiO by nearly 1 V and substantially alter the lifetime of charge carriers and charge transfer resistance at the semiconductor-electrolyte interface. Differences between the anionic and cationic redox couples employed suggest favorable and unfavorable interactions, respectively, with divalent cations at the NiO surface, causing increases and decreases in charge carrier recombination rate constants. Our results highlight the complex interaction between the semiconductor and electrolyte solution and indicate that varying the cation should yield immediate improvements in device metrics for most p-type DSSC systems.
关键词： electrolyte,p-type semiconductor,Cation effects,nickel oxide,metal oxide,dye-sensitized solar cell
更新于2025-09-19 17:13:59
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Thermal oxidation of sputtered nickel nano-film as hole transport layer for high performance perovskite solar cells
摘要： The effect of rapid oxidation temperature on the sputtered nickel (Ni) films to act as a hole transport layer (HTL) for perovskite solar cell (PSCs) was investigated. A nano-sputtered Ni film with a thickness about 100 nm was oxidized at a range of different oxidation temperatures between 350 and 650 °C to work as HTL in an inverted p–i–n configuration. DC Hall measurement in van der Pauw configuration and photoluminescence spectroscopy were used to measure the charge’s mobility and extraction of nickel oxide (NiO) films. The behaviour of the carrier concentration measurements of NiO layers at different oxidation temperatures showed that the Ni layer oxidized at 450 °C had the highest carrier concentration among the other samples. The performance measurements of the fabricated PSCs showed that the nickel oxide hole-transporting layer which has been oxidized at the optimum oxidation temperature of 450 °C has the highest power conversion efficiency (PCE) of 12.05%. Moreover, the characteristic parameters of the optimum cell such as the open-circuit voltage (VOC), short-circuit current density (JSC) and fill factor (FF) were 0.92 V, 19.80 mA/cm2 and 0.331, respectively.
关键词： Sputtering,Thermal oxidation,Hole transport layer,Perovskite solar cells,Nickel nano-film
更新于2025-09-19 17:13:59
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High-efficiency perovskite nanocrystal light-emitting diodes <i>via</i> decorating NiO <sub/>x</sub> on the nanocrystal surface
摘要： Nickel oxides exhibit a great potential as hole transport layers for the fabrication of efficient perovskite light-emitting diodes (LEDs) due to their high carrier mobility and good energy band matching with perovskite nanocrystals. In this work, nickel oxides were directly decorated on the CsPbBr3 nanocrystal surface through adsorption and a sequential oxidation treatment. The resulting sample shows a high photoluminescence quantum-yield of 82%. The LED using CsPbBr3 nanocrystals with nickel oxides achieves a high external quantum efficiency (EQE) of up to 16.8% with a low turn-on voltage of 2.8 V, which is much superior to that of the counterpart LED based on pristine CsPbBr3 nanocrystals (EQE = 0.7%, turn-on voltage = 5.6 V). The excellent performance of the nickel oxide decorated CsPbBr3 nanocrystal device could be attributed to the better energy level matching between the decorated nanocrystals and the transport layers of the device and more balanced charge carrier injection. Furthermore, the operational lifetime of the nickel oxide decorated CsPbBr3 nanocrystal device is 40 times longer than that of the pristine CsPbBr3 nanocrystal device.
关键词： perovskite nanocrystals,photoluminescence quantum-yield,light-emitting diodes,external quantum efficiency,nickel oxides
更新于2025-09-19 17:13:59
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Optimal Design of Narrow Line‐Width Front Contact Grid Pattern for Silicon Solar Cells and Low‐Cost Fabrication of Electroless Nickel Plated Imprint Lithography Hard Stamp
摘要： Herein, a systematic investigation on the design and development of a cost-effective nickel hard stamp suitable for fabrication of a new front-side metallization pattern to reduce the shadow losses in solar cells is demonstrated. Finite element analysis (FEA)–based simulations indicate an optimal ?nger width of (cid:1)20 μm with inter?nger spacing of 1000 μm which can effectively enhance solar cell ef?ciency by (cid:1)1% due to reduced shadow loss. The optimal grid design is further patterned by means of nanoimprint lithography (NIL) followed by an electroless deposition method. A cost-effective, electroless deposited nickel hard template is developed for NIL patterning using UV pattern transfer. To avoid the physical damages during the imprinting process and improve the durability of the NIL stamp, silane-based antiadhesive coating is used which can withstand up to 18 cycles of imprinting process. The nickel hard stamp exhibits improved hardness of 5.63 GPa and roughness of 8 nm and is used to transfer the narrow-line width patterns during the imprinting process. The proposed industry-ready technology overcomes the limitations of the existing screen printing process pertaining to the formation of high-aspect-ratio narrow line-width ?nger grid patterns.
关键词： anti-adhesive coating,front contact metallization,solar cells,nanoimprint lithography,nickel hard stamps
更新于2025-09-19 17:13:59
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The Effect of Lithium‐Doping in Solution‐Processed Nickel Oxide Films for Perovskite Solar Cells
摘要： The effect of substitutional Li doping into NiOx hole transporting layer (HTL) for use in inverted perovskite solar cells was systematically studied. Li doped NiOx thin films with preferential crystal growth along the (111) plane were deposited using a simple solution-based process. Mott-Schottky analysis showed that hole carrier concentration (NA) is doubled by Li doping. Utilizing 4% Li in NiOx improved the power conversion efficiency (PCE) of solar devices from 9.0% to 12.6%. Photoluminescence quenching investigations demonstrate better hole capturing properties of Li:NiOx compared to that of NiOx, leading to higher current densities by Li doping. The electrical conductivity of NiOx is improved by Li doping. Further improvements of the device were made by using an additional ZnO layer onto PCBM, to remove shunt paths, leading to a PCE of 14.2% and a fill factor of 0.72.
关键词： nickel oxide,lithium doping,hole transporting layer,inverted perovskite solar cells
更新于2025-09-19 17:13:59
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Influence of double pulse ablation on the film topography in picosecond pulsed laser deposition of nickel
摘要： An approach to achieve co-axial picosecond laser pulsed pair is proposed. Instead of introducing additional optical devices, this method involves the adjustment of switching-out dynamics in the regenerative amplification process. Experimental results concerning the dependence of laser output behavior on the duration of the quarter-wave voltage applied on the Pockels cell are reported. The influence of ablation mode (single pulse or double pulse) on the morphology of deposited Nickel-films is studied. A significant improvement in the surface morphology with the double pulse mode is observed. Fewer nanoparticles are observed and the thin film appears to be smoother with lower roughness.
关键词： double pulse ablation,nickel,film topography,picosecond pulsed laser deposition
更新于2025-09-19 17:13:59
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Redox-State-Mediated Regulation of Cytochrome?c Release in Apoptosis Revealed by Surface-Enhanced Raman Scattering on Nickel Substrates
摘要： The interaction of cytochrome c (Cyt c) with cardiolipin (CL) is believed to play an important role in the initial events of apoptosis. Herein, we investigate the structural changes of CL-bound Fe2+Cyt c and the correlation with Cyt c release through surface-enhanced Raman spectroscopy (SERS) on nickel substrates. The SERS results together with molecular dynamics simulation reveal that Fe2+Cyt c undergoes autoxidation and a relatively larger conformational alteration after binding with CL, inducing higher peroxidase activity of Cyt c and higher permeability of the CL membrane compared with those induced by the Fe3+Cyt c. The proapoptotic activity and SERS effect of the Ni nanostructures allow the in situ study of the redox-state-dependent Cyt c release from isolated mitochondria, which reveals for the first time that the ferrous state of Cyt c most likely plays a more important role in triggering apoptosis.
关键词： redox state,apoptosis,cytochrome c,nickel,SERS
更新于2025-09-19 17:13:59
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[IEEE 2018 IEEE International Conference on Information and Automation (ICIA) - Wuyishan, China (2018.8.11-2018.8.13)] 2018 IEEE International Conference on Information and Automation (ICIA) - Optimization design of multi-sided reflecting prism in laser line scanning imaging system
摘要： A passive thermal micro-actuator with large area specific work and large displacement, fabricated of electroplated nickel on a silicon substrate is presented. The actuation relies on the thermal expansion of beams in a V-shaped geometry. Two V-shaped beam stacks are aligned opposite to each other and are coupled to a lever transmission. The actuator exhibits low energy losses due to the deformation of the structure and can efficiently convert the thermally induced elastic energy into mechanical work. An analytical model considers these thermally induced mechanical energies and the energy losses caused by the deformation of the material. The calculated deflections are compared with the measured ones and results of finite-element method simulations. The presented actuator operates completely passive, relies only on temperature changes of the surrounding environment, and exhibits a measured temperature-dependent linear deflection coefficient of 1.48 μm/K with a simulated blocking force of 57 μN/K. The structure occupies an area of 2135 × 1831 μm2 and the area specific work is calculated to be 21.7 μJ/K2/m2, beating state of the art thermal actuators. As proof-of-concept, a passive micro-electro-mechanical systems temperature threshold sensor is fabricated, featuring the actuator and a bistable beam that switches between two stable positions when a specific threshold temperature is exceeded.
关键词： Micro mechanical system,electroplated nickel,V-shaped,energy efficient,passive thermal actuator
更新于2025-09-19 17:13:59
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Low-temperature chemical vapor deposition growth of graphene films enabled by ultrathin alloy catalysts
摘要： This report introduces a method for fabricating graphene at low temperatures via chemical vapor deposition enabled by ultrathin (～1 nm) nickel-gold (Ni-Au) catalysts. The unique combination of high carbon (C) solubility Ni, low C solubility Au, and an ultrathin layer of a catalyst demonstrates the effectiveness to produce graphene at 450 °C with the layer number independent of growth duration. In contrast to grain-boundary defined catalyst morphology found in thicker (>20 nm) metal catalysts, the ultrathin catalyst morphology leads to the formation of nanoscale metal “islands” during the growth process, which results in curved graphene covering the catalyst. To test the effect of preactivation of the ultrathin catalyst for the formation of graphene, a preanneal process of the catalyst followed by the introduction of a carbon precursor was also investigated. The preanneal process resulted in the formation of carbon nanotubes (CNTs) in lieu of graphene, displaying the impact of the catalytic surface treatment in relation to the produced materials. The results and discussion presented here detail a low-temperature nanoscale manufacturing process that allows for the production of either graphene or CNTs on an ultrathin catalyst.
关键词： graphene,low-temperature growth,nickel-gold catalysts,chemical vapor deposition,ultrathin alloy catalysts
更新于2025-09-19 17:13:59