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[IEEE 2019 International Energy and Sustainability Conference (IESC) - Farmingdale, NY, USA (2019.10.17-2019.10.18)] 2019 International Energy and Sustainability Conference (IESC) - Metal oxide-based heterojunction thin films for solar cell applications
摘要： The interest and development in a fully green future towards sustainable technology and environmental preservation has spurred exponentially for the past few years. The adoption in clean energy is underway with solar photovoltaic (PV) technology leading the race. To keep PV sector competitive with current conventionally generated electricity, an alternative economic PV module using cheap materials with low-cost deposition method is needed. Among the candidate, metal oxides (MO) semiconductors are great potential materials to achieve this goal due to its massive availability, non-toxicity, chemically stable, and can be deposited using low-cost techniques at ambient condition. In this report, the p-n junction solar cell was fabricated using layer by layer deposition of n-type and p-type metal oxide semiconductors. Co3O4 and CuO were used as absorbing layers and ZnO as a window layer in contact with each other using simple spin coating deposition method. Photocurrent density (JSC), photo voltage (VOC) and the crystallinity of materials were investigated to characterize their optoelectronic properties. It is observed that Co3O4 shows larger crystallite size compared to CuO at 26.66 nm and 24.86 nm, respectively. Samples consisting of Co3O4 and CuO p-n junction solar cell exhibits high absorbance in the visible spectral region of 350 nm to 750 nm. J-V measurement of FTO/ZnO/Co3O4/In heterojunction films exhibits short-circuit current density of 0.391 mA/cm-1 and open-circuit voltage of 0.476 V under the illumination of AM1.5 solar simulation (100mW/cm2). Meanwhile, FTO/ZnO/CuO/In shows short-circuit current density of 0.429 mA/cm-1 and open-circuit voltage of 0.048 V. Thus, it shows that green materials without any environmental issue has high potential in solar cells application.
关键词： CuO,Co3O4,Sol-Gel,Solar Cell,Spin Coating,Heterojunction
更新于2025-09-23 15:21:01
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Carbon Nanotubes - Recent Progress || Stability and Reliability of an Electrical Device Employing Highly Crystalline Single-Walled Carbon Nanotubes as a Field Emitter
摘要： Carbon nanomaterial is drawing keen interest from researchers as well as materials scientists. Carbon nanotubes (CNTs)—and their nanoscale needle shape—offering chemical stability, thermal conductivity, and mechanical strength exhibit unique properties as a quasi-one-dimensional material. Among the expected applications, field emission electron sources appear the most promising industrially and are approaching practical utilization. However, efforts to construct a field emission (FE) cathode with single-walled carbon nanotubes (SWCNTs) have so far only helped average out a non-homogeneous electron emitter plane with large FE current fluctuations and a short emission life-time because they failed to realize a stable emission current owing to crystal defects of the carbon network in CNTs. The utilization of CNTs to obtain an effective cathode, one with a stable emission and low FE current fluctuation, relies on the ability to disperse CNTs uniformly in liquid media. In particular, highly crystalline SWCNTs hold promise to obtain good stability and reliability. The author successfully manufactured highly crystalline SWCNTs-based FE lighting elements that exhibit stable electron emission, a long emission life-time, and low power consumption for electron emitters. This FE device employing highly crystalline SWCNTs has the potential for conserving energy through low power consumption in our habitats.
关键词： wet coating process,high crystallization,field emission,single-walled carbon nanotube,scratch,thin film,planar light source,cathode luminescence
更新于2025-09-23 15:21:01
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Isosorbide-based high performance UV-curable reactive diluents
摘要： In UV-curable coatings, a reactive diluent is mainly used to adjust the viscosity of the formula and participates in UV curing. However, it is still a great challenge to obtain a reactive diluent that has good diluting ability and good mechanical properties. In this study, isosorbide di(meth)acrylate (ISD(M)A) was designed and synthesized as a photocurable reactive diluent. The photo-polymerization kinetics of the reactive diluent were studied using real-time infrared spectroscopy. The diluting ability of reactive diluents in polyurethane acrylic (PUA) and epoxy acrylic (EA) were studied using a rheometer. Reactive diluent was mixed with PUA and EA to prepare a series of UV curable coatings, and the thermomechanical properties, mechanical properties, and basic coating properties of these coatings were evaluated. The results show that for both PUA and EA, ISD(M)A exhibits dilution capabilities similar to those of commercially available reactive diluents. The addition of 30 wt% reduces formula viscosity by three orders of magnitude, but the glass transition temperature (Tg) and pencil hardness of the ISDA-CN981 coating are 62.3 °C and 3H, respectively, which are higher than those of HDDA-CN981 (51.9 °C and 2 H). Moreover, the coatings that contain ISD(M)A have a higher storage modulus and good impact properties. In this work, good dilution ability of the active diluent and high mechanical properties of the coating were simultaneously achieved. These bio-renewable, UV-curable isosorbide-based reactive diluents show promise in green photocuring coatings.
关键词： UV-curable coating,isosorbide,Reactive diluent
更新于2025-09-23 15:21:01
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Hybrid Ligand Exchange of Cu(In,Ga)S <sub/>2</sub> Nanoparticles for Carbon Impurity Removal in Solution Processed Photovoltaics
摘要： The solution processing of Cu(In,Ga)(S,Se)2 photovoltaics from colloidal nanoparticles has long suffered from deleterious carbonaceous residues originating from long chain native ligands. This impurity carbon has been observed to hinder grain formation during selenization and leave a discrete residue layer between the absorber layer and the back contact. In this work, organic and inorganic ligand exchanges were investigated to remove tightly bound native oleylamine ligands from Cu(In,Ga)S2 nanoparticles, thereby removing the source of carbon contamination. However, incomplete ligand removal, poor colloidal stability, and/or selective metal etching was observed for these methods. As such, an exhaustive hybrid organic/inorganic ligand exchange was developed to bypass the limitations of individual methods. A combination of microwave-assisted solvothermal pyridine ligand stripping followed by inorganic capping with diammonium sulfide was developed and yielded greater than 98% removal of native ligands via a rapid process. Despite the aggressive ligand removal, the nanoparticle stoichiometry remained largely unaffected when making use of the hybrid ligand exchange. Furthermore, highly stable colloidal ink formulations using non-toxic dimethyl sulfoxide were developed, supporting stable nanoparticle mass concentrations exceeding 200 mg/mL. Scalable blade coating of the ligand exchanged nanoparticle inks yielded remarkably smooth and microcrack free films with RMS roughness less than 7 nm. Selenization of ligand exchanged nanoparticle films afforded substantially improved grain growth as compared to conventional non-ligand exchanged methods yielding an absolute improvement in device efficiency of 2.8%. Hybrid ligand exchange nanoparticle based devices reached total-area power conversion efficiencies of 12.0%, demonstrating the feasibility and promise of ligand exchanged colloidal nanoparticles for the solution processing of Cu(In,Ga)(S,Se)2 photovoltaics.
关键词： hybrid ligand exchange,blade coating,diammonium sulfide,carbon impurity removal,photovoltaics,grain growth,Cu(In,Ga)(S,Se)2,solution processing,ligand exchange,selenization,microwave-assisted solvothermal,colloidal nanoparticles,device efficiency
更新于2025-09-23 15:21:01
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Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings
摘要： Today’s advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades—jointly known as “glazings”—since current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO2), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions.
关键词： thermochromism,vanadium dioxide,thin film,energy-efficient glazing,coating,sputter deposition,nanoparticle
更新于2025-09-23 15:21:01
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Improving the efficiency of perovskite solar cells using modification of CH3NH3PbI3 active layer: the effect of methylammonium iodide loading time
摘要： In perovskite (PSK) solar cells, the PSK absorber layer plays a vital role in power conversion efficiency (PCE). In this study, we report on the fabrication of mesoporous PSK solar cells using a two-step spin-coating rout with the structure of glass/FTO/compact TiO2/mesoporous TiO2/CH3NH3PbI3 (MAPbI3)/P3HT/Au. The morphology and crystalline structure of the PSK thin film is controlled by changing the CH3NH3I (MAI) loading times (the 20?s, 30?s, 40?s, 60?s) on PbI2 film. The PSK layers are optimized at different MAI loading times in a two-step process to enhance the PCE of the PSK solar cells. The investigation and comparison of the results show that the solar cell containing the absorber layer prepared by solution loading time of the 40?s is more efficient than the other devices. The champion device shows the open-circuit voltage (Voc) of 0.97?V, short current density (Jsc) of 19.30?mA/cm2, and fill factor (FF) of 0.64, which leads to the best PCE of 12.04%.
关键词： MAI loading time,MAPbI3,Perovskite solar cell,CH3NH3PbI3,Spins coating,Active layer
更新于2025-09-23 15:21:01
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Rapid Scalable Processing of Tin Oxide Transport Layers for Perovskite Solar Cells
摘要： The development of scalable deposition methods for perovskite solar cell materials is critical to enable the commercialisation of this nascent technology. Herein, we investigate the use and processing of nanoparticle SnO2 films as electron transport layers in perovskite solar cells, and develop deposition methods for ultrasonic spray-coating and slot-die coating, leading to photovoltaic device efficiencies over 19%. The effects of post-processing treatments (thermal annealing, UV ozone and O2 plasma) are then probed using structural and spectroscopic techniques to characterise the nature of the np-SnO2/perovskite interface. We show that a brief ‘hot air flow’ method can be used to replace an extended thermal anneal, confirming that this approach is compatible with high-throughput processing. Our results highlight the importance of interface management to minimise nonradiative losses, as well as providing a deeper understanding of the processing requirements for large area deposition of nanoparticle metal oxides.
关键词： spray-coating,interfaces,SnO2,perovskite solar cells,scalable processing,tin oxide
更新于2025-09-23 15:21:01
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Solar cell based on vertical graphene nano hills directly grown on silicon
摘要： We demonstrate a solar cell application based on vertical graphene nano hills (VGNH) directly grown without using a catalyst. The photovoltaic device based on VGNH grown on top of interfacial layer Al2O3 is compared with that on top of bare silicon by critically analyzing its electrical properties. The role of the interfacial layer is to minimize surface recombination and enhance its built-in potential. Our key process is simple to fabricate large-area devices, avoiding an unreliable transfer process. In addition, the thickness of VGNH is optimized and the surface texturing of silicon is performed to overcome the crucial problem of the high reflectivity of silicon. A low reflectivity of thick layers of VGNH is achieved with low series resistance despite of the vertical structure, which is beneficial for high photocurrent. A higher work function of VGNH ~ 4.7 eV is measured by KPFM. The conversion efficiency of 10.97% is achieved with an active area of 0.9 cm2 by co-doping with PEDOT: PSS and inorganic acid HNO3. Moreover, the photo-responsivity of the VGNH-based device is estimated as 1.196 AW-1 under deep ultraviolet light.
关键词： vertical graphene,graphene doping,graphene nano hills,directly grown graphene,solar cell,anti-reflecting coating,Schottky junction
更新于2025-09-23 15:21:01
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In Situ and Ex Situ Characterization of the Microstructure Formation in Ni-Cr-Si Alloys during Rapid Solidificationa??Toward Alloy Design for Laser Additive Manufacturing
摘要： Laser beam-based deposition methods such as laser cladding or additive manufacturing of metals promises improved properties, performance, and reliability of the materials and therefore rely heavily on understanding the relationship between chemical composition, rapid solidification processing conditions, and resulting microstructural features. In this work, the phase formation of four Ni-Cr-Si alloys was studied as a function of cooling rate and chemical composition using a liquid droplet rapid solidification technique. Post mortem x-ray diffraction, scanning electron microscopy, and in situ synchrotron microbeam X-ray diffraction shows the present and evolution of the rapidly solidified microstructures. Furthermore, the obtained results were compared to standard laser deposition tests. In situ microbeam diffraction revealed that due to rapid cooling and an increasing amount of Cr and Si, metastable high-temperature silicides remain in the final microstructure. Due to more sluggish interface kinetics of intermetallic compounds than that of disorder solid solution, an anomalous eutectic structure becomes dominant over the regular lamellar microstructure at high cooling rates. The rapid solidification experiments produced a microstructure similar to the one generated in laser coating thus confirming that this rapid solidification test allows a rapid pre-screening of alloys suitable for laser beam-based processing techniques.
关键词： Ni-Cr-Si,laser coating,rapid solidification,anomalous eutectic
更新于2025-09-23 15:21:01
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Solar Cells with High Short Circuit Currents Based on CsPbBr <sub/>3</sub> Perovskite-Modified ZnO Nanorod Composites
摘要： 3-D all-inorganic perovskite solar cells have been built using vertically aligned conductive zinc oxide nanorods as the electron transport layer and optical waveguide. Yttrium doping improved the conductivity and hence the electron transportation of the ZnO achieving a threefold improvement of the solar cell efficiency. The vertically aligned nanorods act as optical waveguides and a scaffold, which improved photoabsorption of the perovskite semiconductor by increasing layer thickness. Our device structure was completed with an exfoliated multilayer graphite back contact for effective hole-extraction. The ZnO was most significantly modified by nanometre scale coatings of TiO2 in order to passivate the surface and reduce charge recombination, as measured by photoluminescence spectroscopy. This led to greatly improved charge transfer. This strategy led to an overall nine times enhancement in the solar cell efficiency, yielding a competitive top value of 5.83%. More importantly, the all-inorganic solar cells demonstrated excellent stability, showing no decline in initial performance after 1000 hour storage in ambient conditions. This work presents yttrium doped ZnO nanorods as a suitable replacement for mesoporous TiO2, achieving a high short circuit current of 10.5 mA cm-2 for CsPbBr3 perovskite devices.
关键词： Graphite,ambient synthesis,Inorganic perovskite,TiO2 coating,ZnO nanorods
更新于2025-09-23 15:21:01