MoOx Layer Research Articles

Metal-to-insulator phase transition of molybdenum oxide for reversible writing and erasing information encryption

Abstract We have reported a theoretical device design for reversible writing and erasing information encryption using a simple two layered structure, which consists of a MoOx layer and a SiO2 space layer on a silver substrate. The MoOx layer can be switched between two phases, i.e., metallic MoO2 and insulating MoO3. The phase transition of MoOx possesses very complicated processes, which makes it advantageous for information decryption. Generally, in the proposed structure with metallic MoO2, various colors can be generated due to the F-P enhanced absorption at wavelengths where construction interference occurs. However, owing to the low loss of insulating MoO3 in visible region, the absorption is low though out the whole visible region, thus all colors can be erased to white. Therefore, the color image information can be written and erased with our proposed structure by switching MoOx between phases of metallic MoO2 and insulating MoO3. The proposed image encryption device can be acquired easily by masking and coating processes. We believe our results provides a new way in designing encryption devices.

Upright Pyramid Surface Textures for Light Trapping and MoOx Layer in Ultrathin Crystalline Silicon Solar Cells

In this work, ray tracing is used to investigate the optical characteristics of various surface structures in ultrathin crystalline silicon (c-Si) for solar cells. Ultrathin c-Si with a thickness of 20 μm is used as the substrate. The light trapping includes front upright pyramids with a molybdenum oxides (MoOx) anti-reflection (AR) layer. Planar ultrathin c-Si (without a MoOx AR layer and upright pyramids) is used as a reference. The wafer ray tracer was developed by a photovoltaic (PV) lighthouse to model the MoOx AR layer to reduce the front surface reflectance and impacts of the AR layer on ultrathin Si solar cells. The optical properties are calculated on the AM1.5 global solar energy spectrum across the 200–1200 nm wavelength region. From the absorbance profile, the photogenerated current density (Jph) in the substrate is also calculated with various surface structures. The front upright pyramids with the MoOx layer result in the largest absorbance enhancement due to the enhanced light scattering by the pyramids and MoOx AR layer. The Jph of 37.41 mA/cm2 is improved when compared to the planar ultrathin c-Si reference. This study is significant as it illustrates the potential of ultrathin c-Si as a promising PV module technology in the future.

Interdigitated‐back‐contacted silicon heterojunction solar cells featuring novel MoOx‐based contact stacks

AbstractThe fabrication process of interdigitated‐back‐contacted silicon heterojunction (IBC‐SHJ) solar cells has been significantly simplified with the development of the so‐called tunnel‐IBC architecture. This architecture utilizes a highly conductive (p)‐type nanocrystalline silicon (nc‐Si:H) layer deposited over the full substrate area comprising pre‐patterned (n)‐type nc‐Si:H fingers. In this context, the (p)‐type nc‐Si:H layer is referred to as blanket layer. As both electrodes are connected to the same blanket layer, the high lateral conductivity of (p)nc‐Si:H layer can potentially lead to relatively low shunt resistance in the device, thus limiting the performance of such solar cells. To overcome such limitation, we introduce a thin (<2 nm) full‐area molybdenum oxide (MoOx) layer as an alternative to the (p)nc‐Si:H blanket layer. We demonstrate that the use of such a thin MoOx minimizes the shunting losses thanks to its low lateral conductivity while preserving the simplified fabrication process. In this process, a novel (n)‐type nc‐Si:H/MoOx electron collection contact stack is implemented within the proposed solar cell architecture. We assess its transport mechanisms via electrical simulations showing that electron transport, unlike in the case of tunnel‐IBC, occurs in the conduction band fully. Moreover, the proposed contact stack is evaluated in terms of contact resistivity and integrated into a proof‐of‐concept front/back‐contacted (FBC) SHJ solar cells. Contact resistivity as low as 100 mΩcm2 is achieved, and fabricated FBC‐SHJ solar cells obtain a fill factor above 81.5% and open‐circuit voltage above 705 mV. Lastly, the IBC‐SHJ solar cells featuring the MoOx blanket layer are fabricated, exhibiting efficiencies up to 21.14% with high shunt resistances above 150 kΩcm2. Further optimizations in terms of layer properties and fabrication process are proposed to improve device performance and realize the efficiency potential of our novel IBC‐SHJ solar cell architecture.

Enhancing performance of heterojunction silicon solar cells through atomic-layer-deposited MoOx hole contact and atomic-layer-deposited AlZnO layer

We present the performance enhancement of a heterojunction Si solar cell facilitated by incorporating an atomic-layer-deposited (ALD) MoOx hole contact layer and an ALD Al-doped ZnO (AZO) transparent conductive oxide (TCO). ALD MoOx thin films as a hole-selective contact layer instead of P+-doped amorphous Si in Si heterojunction solar cells, with subsequent growth of ALD AZO films grown on the MoOx layer preceding the indium-tin-oxide sputtering deposition. Integrating ALD MoOx hole-selective contact and ALD AZO TCO manifests an augmentation in the short-circuit current in heterojunction Si solar cells due to the heightened carrier transport and concurrent reduction in sputtering-induced damage. Consequently, the heterojunction Si solar cell employing the ALD MoOx film and ALD AZO layer yielded a 1.1 % increase in efficiency relative to the reference heterojunction solar cell.

(Invited) Interface Treatments for High-Efficiency MoOx Based Silicon Heterojunction Solar Cells

Silicon based solar cells dominate the market of photovoltaics, which hold the highest potential for green electricity production. A front/back-contacted architecture combined with the silicon-based heterojunction (SHJ) concept realized a world record efficiency of 26.3%1. However, conventional silicon-based doped layers, which work as carrier selective transport layers, are not optically transparent.Transition metal oxides are promising candidates for SHJ solar cells due to their advantageous opto-electronic properties. Molybdenum oxide (MoOx) with high work function (WF) has achieved highly efficient solar cells with 23.5% efficiency2. However, depositing high quality MoOx thin film on top of a-Si:H is challenging due to highly reactive surfaces3. This interaction may result in interfacial oxidation, lower Mo oxidation states and reduced WF4,5. In turn, electrical performances of solar cells featuring MoOx are poorer3 than standard SHJ devices.Several attempts have been made to prevent the reaction between MoOx and (i)a-Si:H. Pre-annealing4 of a-Si:Hand pre-growth of SiOx layer6 have been proposed as effective ways to prevent the degradation of MoOx. Nevertheless, those approaches require extra process steps that make MoOx integration not immediately viable in industrial environment. In our previous work, we proposed a plasma treatment (PT) at MoOx/(i)a-Si:H interface that demonstrated to mitigate dipole effect and resulted in improved cell performance7. After optimizing the interface treatment, even thinner MoOx layer could be applied.The solar cells were fabricated using 260±20 μm 4-inch double-side textured n-type <100> FZ wafers. (i)a-Si:H was deposited by plasma-enhanced chemical vapor deposition on both sides, while (n)a-Si:H only at the rear side. We carried out two different plasma treatments on the (i)a-Si:H interface prior MoOx deposition: one called PT from a mixture of SiH4, H2 and CO2 and another called PTB from a mixture of SiH4, H2, CO2 and B2H6. One sample without plasma treatment (noPT) was used as reference to evaluate the efficacy of the proposed method. A thickness series from 1 to 4 nm of MoOx was thermally evaporated from MoO3 powder at the pressure of 5×10-6 mbar. After that, optimized 50-nm and 150-nm thick tungsten-doped indium oxide (IWO) layers were sputtered through a hard mask at front and rear side, respectively, defining six 2×2 cm2 solar cells per wafer. As metal contact at the front side, we used room temperature Cu plating8 with a metal coverage fraction of 1.575%; at the rear side, 500-nm thick Ag layer was sputtered on the full device area.We studied the impact of different plasma treatment conditions on MoOx film quality and cells’ performance. MoOx film quality was assessed based on O vacancies inside the film4. The samples with interface treatments contain less O vacancies than the sample without treatment. It is noticeable that the cell precursors endowed with PTB yield higher fill factor (FF) than other types of precursors. Instead, PT and noPT samples benefitted from high short-circuit current density (J SC). Ultimately, PTB and PT samples achieved similar conversion efficiency. For the variation of MoOx thickness, we observed that even a slightly change in its thickness influences the solar cells’ electrical performance drastically. An ultra-thin, ~1.7-nm thick MoOx layer could provide sufficient field passivation (open circuit voltage, V OC = 721.4 mV) and good opto-electrical properties (FF = 82.18% and J SC-illuminated-area = 40.20 mA/cm2). With our approach we demonstrate word record cell with ISFH-certified conversion efficiency of 23.83% 9. 1 LONGi Solar 2021. 2 J. Dréon, et al., Nano Energy, 2020. 3 J. Geissbühler et al., Appl. Phys. Lett. 2015. 4 M.T. Greiner, et al., Adv. Funct. Mater. 2013. 5 M.T. Greiner, et al., Adv. Funct. Mater. 2012. 6 J. Tong, et al. ACS Appl. Mater. Interfaces. 2021. 7 L. Mazzarella, et al., Prog Photovolt Res Appl. 2020. 8 C. Han, et al., Solar RRL 2022. 9 L. Cao, et al., Prog. Photovolt. 2022.

Effect of p-MoOx interfacial layer on the photovoltaic performances of p-MoS2/n-Si heterojunction solar cells by theoretical simulation

As one of particular 2D transition metal dichalcogenide materials, the outstanding properties of MoS2 enable the promising formation of superior homo or heterojunction solar cells. However, in the process of introducing oxygen treatment to modify the interface defects of MoS2/Si solar cells, or modulate the Fermi level of MoS2 films, a thin layer of p-MoOx capping layer is generally produced next to MoS2. In order to essentially clarify the functional mechanism of MoOx layer, p-MoS2/n-Si heterojunction solar cells with or without MoOx interfacial layer are simulated using SCAPS software. The influences of band gap, electron affinity, thickness of MoS2 and front contact barrier height on the performances of p-MoS2/n-Si solar cells are theoretically studied. It is demonstrated that p-MoS2/n-Si solar cell can achieve a high efficiency of 21.9%. With the appearance of MoOx, the effect of location, electron affinity and thickness of MoOx on the photovoltaic performances p-MoS2/n-Si heterojunction solar cells are studied. The efficiencies of p-MoS2/p-MoOx/n-Si solar cells are significantly reduced to be lower than 11.4%, p-MoOx/p-MoS2/n-Si solar cells maintain superior efficiencies over 20% in a large range of electron affinities lower than 3.0 eV for p-MoOx. Consequently, in modulating the Fermi level of MoS2 films through MoOx doping, p-MoOx capping layer is suggested to be located between MoS2 and front electrode rather than at p-MoS2/n-Si interface, to maintain the excellent performances of p-MoS2/n-Si solar cells.

Mott-Schottky heterojunctions of ultrafine Ni3Fe confined in amorphous molybdenum oxide for efficient and durable overall water electrolysis

NiFe alloys are highly active towards oxygen evolution reaction (OER), and it is important to further enhance their catalytic activity and working stability. Herein, a series of Mott-Schottky electrocatalysts of ultrafine Ni3Fe confined in amorphous molybdenum oxide (Ni3Fe/MoOx) are fabricated via hydrogenation treatment. The experimental results and computational calculations show that the amorphous MoOx improves the surface wettability, modulates the electronic structure, accelerates the charge transfer, favors the generation of NiOOH species, and facilitates the formation of the *OOH intermediates. The Ni3Fe/MoOx phase interfaces are engineered by controlling the MoOx content to optimize the catalytic activity, and the Ni3Fe/MoOx-0.5 catalyst with the optimized Mott-Schottky heterojunction exhibits the highest catalytic activity with an overpotential of 224 mV at 10 mA cm−2. Additionally, the amorphous MoOx layer greatly enhances the working stability of the Ni3Fe, showing almost no activity degradation in both two-electrode and three-electrode systems.

Effect of anti-reflecting layers on device performance of SWCNTs/Si hetero-junction hybrid solar cells

Single wall carbon nano-tubes/Silicon (SWCNTs-Si) solar cells have the ability of being an ideal substitute to the expensive crystalline based Silicon solar cells because of promising cell efficiency and cost effectiveness. Single wall carbon nanotubes (SWCNTs) thin films are deposited on n-type silicon substrate to obtain heterojunction solar cells. To enhance the performance of these heterojunction solar cells Molybdenum Oxide and Tin Chloride are deposited on SWCNTs/Si substrates respectively. It has been confirmed from Raman spectroscopy that the doping of MoOx has enhanced p type behaviour of SWCNTs, MoOx layer acts as an anti-reflection layer and protects the n-Si and SWCNTs interface from deposition of oxides. While on the other hand SnCl2 acts as antireflection layer, enhances p-type doping of SWCNTs and suppression of recombination. Three hybrid heterojunction solar cells were fabricated by using MoOx on SWCNTs/Si, SnCl2 on SWCNTs/Si and both MoOx and SnCl2 on SWCNTs/Si, respectively. For structural analysis we have performed X-Ray diffraction (XRD) and Raman analysis. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) are performed for surface analysis which confirms the smooth protected layers of MoOx and SnCl2; furthermore confirmed the presence of deposited metal oxide MoOx and SnCl2. Optical properties such as reflectance of thin films studies by UV visible spectroscopy. Maximum efficiency of 8.2% has been obtained by using both MoOx and SnCl2 on SWCNTs/Si solar cell.

Amorphous MoOx with High Oxophilicity Interfaced with PtMo Alloy Nanoparticles Boosts Anti-CO Hydrogen Electrocatalysis.

Advancing electrocatalysts for alkaline hydrogen oxidation/evolution reaction (HOR/HER) is essential for anion exchange membrane-based devices. The state-of-the-art Pt-based electrocatalysts for alkaline HOR suffer from low intrinsic activities and severe CO poisoning due to the challenge of simultaneously optimizing surface adsorption toward different adsorbates. Herein, this challenge is overcome by tuning an atomic MoOx layer with high oxophilicity onto PtMo nanoparticles (NPs) with optimized Had , OHad , and COad adsorption for boosting anti-CO-poisoning hydrogen-cycle electrocatalysis in alkaline media. For alkaline HOR, this catalyst exhibits high kinetics and an exchange current density of 3.19mAµgPt -1 at 50mV versus reversible hydrogen electrode and 0.83mAcmPt -2 , 10.3- and 3.8-fold higher than those of commercial Pt/C, respectively. For alkaline HER, it achieves an unprecedented overpotential of 37mV at 10mAcm-2 . Experimental and theoretical studies show that the orchestrated electronic and oxophilic regulation of the PtMo/MoOx interface NPs simultaneously optimizes Had and OHad adsorption for boosting alkaline hydrogen electrocatalysis, whereas reactive oxygen from the amorphous MoOx atomic layer lowers the CO oxidation reaction barrier, leading to superior anti-poisoning ability even at 100ppm CO.

MoOx layer with abundant oxygen vacancies modified on Sn-doped α-Fe2O3 film for enhanced photoelectrochemical water oxidation performance

MoOx layer with abundant oxygen vacancies modified on Sn-doped α-Fe2O3 film for enhanced photoelectrochemical water oxidation performance

Highly reliable MoOx/Ag NW bilayer transparent conductive thin films fabricated by all solution process and transparent heater application

The chemical instability and the decomposition of Ag nanowires (NWs) during thermal process can result in irreversible structural damage, suppressing the practical use of pure Ag NWs based transparent conductive thin films (TCTFs). In this paper, novel MoOx/Ag NW bilayer TCTFs are uniformly fabricated on glass substrates via all solution process. The electrical and optical properties of MoOx/Ag NW bilayers can be controlled by the density of the Ag NW networks. At optimal preparation conditions, MoOx/Ag NW bilayer thin films show low sheet resistance of 10.8 Ω/sq. and high optical transmittance of 85% in the visible region. The covering of MoOx layer improves the thermal stability and adhesivity of the Ag NW networks. Especially, the MoOx/Ag NW bilayer thin films are robust and able to withstand a high temperature of 300 °C in air, without deterioration of performance. The resistance does not show significant change after taping test, indicating a strong adhesion of Ag NWs to the substrate. In contrast to the degradation of pure Ag NW networks including the significant reduction of its conductivity when subjected to a series of harsh corrosion environments, the MoOx/Ag NW bilayer thin films survive structurally and retain their conductivity. Finally, the bilayer thin film is chosen to fabricate a transparent heater, which exhibits excellent heating performance. Its deicing and defogging availabilities are also shown by deicing and defogging tests.

A study of highly activated hydrogen evolution reaction performance in acidic media by 2D heterostructure of N and S doped graphene on MoOx

AbstractHerein, a layer of molybdenum oxide (MoOx), a transition metal oxide (TMO), which has outstanding catalytic properties in combination with a carbon‐based thin film, is modified to improve the hydrogen production performance and protect the MoOx in acidic media. A thin film of graphene is transferred onto the MoOx layer, after which the graphene structure is doped with N and S atoms at room temperature using a plasma doping method to modify the electronic structure and intrinsic properties of the material. The oxygen functional groups in graphene increase the interfacial interactions and electrical contacts between graphene and MoOx. The appearance of surface defects such as oxygen vacancies can result in vacancies in MoOx. This improves the electrical conductivity and electrochemically accessible surface area. Increasing the number of defects in graphene by adding dopants can significantly affect the chemical reaction at the interfaces and improve the electrochemical performance. These defects in graphene play a crucial role in the adsorption of H+ ions on the graphene surface and their transport to the MoOx layer underneath. This enables MoOx to participate in the reaction with the doped graphene. N‐ and S‐doped graphene (NSGr) on MoOx is active in acidic media and performs well in terms of hydrogen production. The initial overpotential value of 359 mV for the current density of −10 mA/cm2 is lowered to 228 mV after activation.

Plasma synthesized molybdenum derived nano-fiber films: The influence of surface composition on their SERS effect

Owing to the direct activation of reactant species, plasma has been playing an important role in surface engineering in recently years, especially for production of nano-materials. Herein, molybdenum derived nano-fiber films have been synthesized via thermal plasma method under the irradiation of dense helium plasma. Surface composition of the nano-fiber films can be controlled by following plasma treatment or chemical reaction to produce molybdenum nitrides or molybdenum oxides while the nanofiber structure is retained. When applied as substrates for the Raman detection of Rhodamine 6G molecule (R6G), the Mo nano-fiber film with amorphous MoOx layer on surface showed strong SERS effect, by pushing the detection limit of R6G from 10−4 M to 10−7 M, while those with MoO3 and Mo2N surface compositions only displayed very weak or none SERS effect. These results indicated that the surface composition of the nano-fiber molybdenum films rather than surface structure plays an important role regarding to their SERS performance.

Modulation of the TCO/MoOx Front Contact Enables &gt;21% High-Efficiency Dopant-Free Silicon Solar Cells

Highly efficient dopant-free silicon solar cell requires effective electron- and hole-selective contacts. We have recently reported a remarkable efficiency of 21.3% for dopant-free silicon solar cells with a low work function and transparent and conductive MgFxOy electron extraction. The transparent conductive oxide (TCO) films and molybdenum oxide (MoOx) front hole contact also play significant roles in the high efficiency of dopant-free solar cells. In this study, zinc-doped indium oxide (IZO), tin-doped indium oxide (ITO), and titanium-doped indium oxide (ITiO) have been deposited via magnetron sputtering at room temperature. The work function and optoelectrical properties of TCO films and energy band bending together with the MoOx layer are investigated. The impact of this band bending on the photoelectrical performances of devices is analyzed in detail as a function of the MoOx/TCO work function mismatch. The optimized IZO film presents the highest work function (5.21 eV) and conductivity (2140 S/cm), resulting in reduced barrier height at the MoOx/TCO interface and enhanced hole-selective transport. The light-soaking treatment is introduced to repair the sputtered damage during the IZO deposition. Finally, an impressive cell efficiency of 21.0%, together with Voc, FF, and Jsc of 712.4 mV, 76.4%, and 38.6 mA/cm2, respectively, shows great potential and provides an effective solution to obtain highly efficient dopant-free silicon solar cells.

Achieving 23.83% conversion efficiency in silicon heterojunction solar cell with ultra‐thin MoOx hole collector layer via tailoring (i)a‐Si:H/MoOx interface

AbstractThin films of transition metal oxides such as molybdenum oxide (MoOx) are attractive for application in silicon heterojunction solar cells for their potential to yield large short‐circuit current density. However, full control of electrical properties of thin MoOx layers must be mastered to obtain an efficient hole collector. Here, we show that the key to control the MoOx layer quality is the interface between the MoOx and the hydrogenated intrinsic amorphous silicon passivation layer underneath. By means of ab initio modelling, we demonstrate a dipole at such interface and study its minimization in terms of work function variation to enable high performance hole transport. We apply this knowledge to experimentally tailor the oxygen content in MoOx by plasma treatments (PTs). PTs act as a barrier to oxygen diffusion/reaction and result in optimal electrical properties of the MoOx hole collector. With this approach, we can thin down the MoOx thickness to 1.7 nm and demonstrate short‐circuit current density well above 40 mA/cm2 and a champion device exhibiting 23.83% conversion efficiency.

Surface morphology engineering of metal oxide-transition metal dichalcogenide heterojunction

ABSTRACT A tremendous effort has been made to develop 2D materials-based FETs for electronic applications due to their atomically thin structures. Typically, the electrical performance of the device can vary with the surface roughness and thickness of the channel layer. Therefore, a two-step surface engineering process is demonstrated to tailor the surface roughness and thickness of MoSe2 multilayers involving exposure of O2 plasma followed by dipping in (NH4)2S(aq) solution. The O2 plasma treatment generated an amorphous MoOx layer to form a MoOx/MoSe2 heterojunction, and the (NH4)2S(aq) treatment tailored the surface roughness of the heterojunction. The ON/OFF current ratio of MoSe2 FET is about 1.1 × 105 and 5.7 × 104 for bare and chemically etched MoSe2, respectively. The surface roughness of the chemically treated MoSe2 is higher than that of the bare, 4.2 ± 0.5 nm against 3.6 ± 0.5 nm. Conversely, a 1-hour exposure of the multilayer MoOx/MoSe2 heterostructure with the (NH4)2S(aq) solution removed the amorphous oxide layer and scaled down the thickness of MoSe2 from ~92.2 nm to ~38.9 nm. The preliminary study shows that this simple two-step strategy can obtain a higher surface-area-to-volume ratio and thickness engineering with acceptable variation in electrical properties.

Balanced electron and hole injection and transport in OLEDs by using transparent electrodes

In this study, electron and hole injection, and transport in semi-transparent organic light-emitting diodes, including dielectric/metal/dielectric (DMD) electrodes, were investigated. The DMD electrode was modified by incorporating a 5 nm-thick Cs:MoOx layer and a 10 nm-thick 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN) layer to improve the electron and hole injection in standard and inverse structures, respectively. The inverse structure showed a reasonably good and stable external quantum efficiency due to the well-balanced carrier densities at both low and high voltages which was confirmed by an electrical simulation study. Also, the peak position of the hole and electron recombination rate in the inverse structure was located on the ITO side, which is beneficial for reducing exciton quenching and photon absorption by metallic electrodes.

Functionalized and Chemically Exfoliated Molybdenum Oxide Nanosheets As Hybrid Electrodes for High Energy Density Supercapacitors

Energy storage systems are critical for regulating and implementing intermittent renewable resources. In addition, the fast development of energy storage systems accelerated the development of electric vehicles. Supercapacitors' unique properties such as high energy storage, high power output, and varied operational range shall allow them to close the gap between batteries and conventional capacitors.1 In the last few decades, enormous efforts were exalted to enhance the supercapacitors' performance by developing new electrode materials that have a structure with an easy ion diffusion path and a high electrochemical surface area.2 In this work, modified molybdenum oxide (MoOx) nanocomposites have been prepared using a facile hydrothermal-aided process, resulting in 3-dimensional (3D) crumpled MoOx nanosheets intercalated with sulfanilamide (SA) or Adenine (Ad). The intercalation of SA or Ad prevented the aggregation of the MoOx nanosheets and allowed the diffusion of electrolyte ions into the MoOx layers. The synthesized MoOx nanocomposites electrodes exhibited a high specific capacitance at 2 A/g and high stability at 10 A/g over 3000 cycles. The assembled symmetric supercapacitor device consisting of MoOx nanocomposites delivered specific energy and specific power of 66.74 Wh/kg and 3 kW/kg, respectively at 3 A/g, demonstrating a high potential for use in constructing high-performance supercapacitors.

Simulation of p-type c-Si solar cells with metal oxides as carrier-selective contacts

The silicon heterojunction (SHJ) solar cell has been one of the most promising candidates for the photovoltaic (PV) market because of its high efficiency, simple structure and mature fabrication process. By replacing the p-type and n-type doped silicon layers with metal oxides, the so-called dopant-free asymmetric heterocontacts (DASH) solar cell can be formed, which will be easy to achieve full-surface passivation and selective carrier transport. In this study, the AFORS-HET software was used to simulate the Ag grid/ITO/ZnO/c-Si(p)/MoOX/Ag device configuration, in which ZnO was used as electron-selective contact and MoOX as hole-selective contact. The influence of work function (WF) of MoOX layer, thickness and doping concentration of ZnO layer, doping concentration of crystalline silicon (c-Si) layer on the device performance were investigated. The simulation results demonstrated that the application of ZnO layer and MoOX layer as carrier-selective layers can significantly increase the open-circuit voltage (VOC) and short-circuit current density (JSC). After a series of optimization, the simulated champion conversion efficiency (Eff) can reach 27.64 %, which will provide meaningful information for subsequent experiment research of DASH solar cells.

Metallic MoOx layer promoting high-valence Mo doping into CoP nanowires with ultrahigh activity for hydrogen evolution at 2000 mA cm-2

High-valence metals such as Mo, W, etc. can modulate the adsorption and desorption energy of 3d-metal-based electrocatalysts, favorable for the intrinsic activity for hydrogen evolution reaction (HER) at large current density. However, the facile and exact incorporation of high-valence metals remains a big challenge. Herein, a metallic MoOx layer has been designed via anodization of Mo foil to achieve high-valence Mo doping into CoP to finally form the real active component Mo-CoP for HER. The activated metallic MoOx layer provides an optimized Mo doping into CoP, obtaining Mo-CoP/MoOx with ~226 mV (alkaline) and ~275 mV (acidic) at > 2000 mA cm-2. Meanwhile, in-situ grown F-Mo-CoP/MoOx controllable treated by fluoroaniline possesses enhanced the structural robustness of Mo-CoP/MoOx with long-term stability at large current density. This work not only illustrates the facile approach of regulating electron structure via high-valence metal doping, but it also provides the rational strategy for enhanced stability for industrial applications.