Journal articles: 'Heterojunctions - Nanostructured Materials'

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Du, Meiqi, Shengxin Cao, Xiaozhou Ye, and Jianfeng Ye. "Recent Advances in the Fabrication of All-Solid-State Nanostructured TiO2-Based Z-scheme Heterojunctions for Environmental Remediation." Journal of Nanoscience and Nanotechnology 20, no. 9 (September 1, 2020): 5861–73. http://dx.doi.org/10.1166/jnn.2020.18719.

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Nanostructured TiO2-based Z-scheme heterojunctions have been widely accepted to be among the most effective photocatalysts for environmental remediation owing to their broadened light absorbance, high efficiency of photogenerated charge carrier separation, and well-preserved strong oxidation and reduction capability. In this review, we will first introduce the photogenerated charge carrier transportation mechanism of three different types of Z-scheme heterojunction systems, namely, liquid-phase Z-scheme photocatalytic system, all-solid-state indirect Z-scheme photocatalytic system, and all-solid-state direct Z-scheme photocatalytic system. Subsequently, we will describe the recent advances toward the rational design and fabrication of all-solid-state nanostructured TiO2-based Z-scheme heterojunctions. The applications of the thus-constructed all-solid-state nanostructured TiO2-based Z-scheme heterojunctions in the degradation of volatile organic compounds, removal of waste water organic pollutants, and upgradation of greenhouse gas CO2 will then be presented one by one. Finally, the advantages and disadvantages of all-solid-state nanostructured TiO2-based Z-scheme heterojunction for photocatalytic environmental remediation will be briefly discussed, and the direction of future development will be prospected as well.

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Yang, Shulin, Gui Lei, Huoxi Xu, Zhigao Lan, Zhao Wang, and Haoshuang Gu. "Metal Oxide Based Heterojunctions for Gas Sensors: A Review." Nanomaterials 11, no. 4 (April 17, 2021): 1026. http://dx.doi.org/10.3390/nano11041026.

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The construction of heterojunctions has been widely applied to improve the gas sensing performance of composites composed of nanostructured metal oxides. This review summarises the recent progress on assembly methods and gas sensing behaviours of sensors based on nanostructured metal oxide heterojunctions. Various methods, including the hydrothermal method, electrospinning and chemical vapour deposition, have been successfully employed to establish metal oxide heterojunctions in the sensing materials. The sensors composed with the built nanostructured heterojunctions were found to show enhanced gas sensing performance with higher sensor responses and shorter response times to the targeted reducing or oxidising gases compare with those of the pure metal oxides. Moreover, the enhanced gas sensing mechanisms of the metal oxide-based heterojunctions to the reducing or oxidising gases are also discussed, with the main emphasis on the important role of the potential barrier on the accumulation layer.

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Li, Jian, Pablo Jiménez-Calvo, Erwan Paineau, and Mohamed Nawfal Ghazzal. "Metal Chalcogenides Based Heterojunctions and Novel Nanostructures for Photocatalytic Hydrogen Evolution." Catalysts 10, no. 1 (January 7, 2020): 89. http://dx.doi.org/10.3390/catal10010089.

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The photo-conversion efficiency is a key issue in the development of new photocatalysts for solar light driven water splitting applications. In recent years, different engineering strategies have been proposed to improve the photogeneration and the lifetime of charge carriers in nanostructured photocatalysts. In particular, the rational design of heterojunctions composites to obtain peculiar physico-chemical properties has achieved more efficient charge carriers formation and separation in comparison to their individual component materials. In this review, the recent progress of sulfide-based heterojunctions and novel nanostructures such as core-shell structure, periodical structure, and hollow cylinders is summarized. Some new perspectives of opportunities and challenges in fabricating high-performance photocatalysts are also discussed.

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Mamedov, Huseyn, Mustafa Muradov, Zoltan Konya, Akos Kukovecz, Krisztian Kordas, Syed Ismat Shah, Vusala Mamedova, Khumar Ahmedova, Elgun Tagiyev, and Vusal Mamedov. "Fabrication and characterization of c-Si/porous-Si/CdS/ZnxCd1-xO heterojunctions for applications in nanostructured solar cells." Photonics Letters of Poland 10, no. 3 (October 1, 2018): 73. http://dx.doi.org/10.4302/plp.v10i3.813.

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Solar cells based on c-Si/porous-Si/CdS/ZnxCd1-xO heterojunctions were synthesized by depositing CdS films on c-Si/porous-Si (PS) substrates by electrochemical deposition (ED). PS layers with systematically varied pore diameter (8-45 nm) and were fabricated on p-type c-Si wafers using electrochemical etching. The window layers of ZnxCd1-xO with several Zn concentrations(x=0.2; 0.4; 0.5 and 0.6) were also deposited on the CdS buffer layers by ED. The photoelectrical properties of heterojunctions were studied as functions of PS pore size and Zn content in ZnxCd1-xO. The optimal pore size and Zn contents were found to be 10 nm and x=0.6, respectively. These yielded a solar cell sample exhibiting an efficiency of 9.9%, the maximum observed in this study. Full Text: PDF ReferencesM.A.Green. "Limiting efficiency of bulk and thin-film silicon solar cells in the presence of surface recombination", Progress in Photovoltaic 7, 327 (1999). CrossRef P.Papet, O. Nichiporik, A. Kaminski et al. "Pyramidal texturing of silicon solar cell with TMAH chemical anisotropic etching", Solar Energy Materials and Solar Cells 90, 2319 (2006). CrossRef P. Vitanovet et al. "High-efficiency solar cell using a thin porous silicon layer", Thin Solid Films 297, 299 (1997). CrossRef L. Santinacci et al. "Electrochemical and optical characterizations of anodic porous n-InP(1 0 0) layers", Electrochim. Acta 56, 878 (2010). CrossRef V.Lehmann. "The Physics of Macropore Formation in Low Doped n‐Type Silicon", J. Electrochem. Soc. 140, 2836 (1993). CrossRef Bisi O et al. "Porous silicon: a quantum sponge structure for silicon based optoelectronics", Surface Science Reports 38, 1 (2000). CrossRef A.I. Raid et al. Applied Nanoscience 7, 9 (2016). CrossRef M.A. Naser et al. "Characteristics of Nanostructure Silicon Photodiode using Laser Assisted Etching", Procedia Engineering 53, 393 (2013). CrossRef D.H. Oh et al. J. Ceram. Process. Res. "Effects of a H2SO4 treatment on the optical properties in porous Si layers and electrical properties of diode devices fabricated with a H2SO4 treated porous Si layer", 9, 57 (2008). DirectLink H. Foll et al. "Formation and application of porous silicon", Materials Science and Engineering R 280, 1 (2002). CrossRef P. Granitzer et al. "Porous Silicon—A Versatile Host Material", Materials 3, 943 (2010). CrossRef G. Korotcenkov, Porous Silicon: From Formation to Application (Taylor and Francis Group, CRC Press, Boca Raton, USA, 2016). DirectLink V.Y. Yerokhov. "Porous silicon in solar cell structures: a review of achievements and modern directions of further use", Renewable and Sustainable Energy Rev. 3, 291 (1999). CrossRef A. Ramizy et al. "New optical features to enhance solar cell performance based on porous silicon surfaces", Appl. Surf. Science 257, 6112 (2011). CrossRef F. Ruske et al. "Large area ZnO:Al films with tailored light scattering properties for photovoltaic applications", Thin Solid Films 515, 8695 (2007). CrossRef Y. Alivov et al. "Observation of 430 nm electroluminescence from ZnO/GaN heterojunction light-emitting diodes", Appl. Phys. Lett. 83, 2943 (2003). CrossRef G.V. Lashkarev et al. "Properties of zinc oxide at low and moderate temperatures", Low Temp. Phys. 37, 289 (2011). CrossRef P.M. Devshette et al. "Growth and physical properties of ZnxCd1−xO thin films prepared by spray pyrolysis technique", J. of Alloys and Compunds 463, 576 (2008). CrossRef Y. Caglar et al. "Morphological, optical and electrical properties of CdZnO films prepared by sol–gel method", J. Phys. D: Appl. Phys. 42, 065421 (2009). CrossRef A. Abdinov et al. "Photosensitivity of p,n-Si/n-Cd1−xZnxS heterojunctions manufactured by a method of electrochemical deposition", Thin Solid Films 480-481, 388 (2005). CrossRef A Abdinov et al. "Investigation of electrodeposited p-Si/Cd1 − xZnxS1 − ySey heterojunction solar cells", Thin Solid Films 511-512,140 (2006) CrossRef J.B. Orhan et al. "Nano-textured superstrates for thin film silicon solar cells: Status and industrial challenges", Sol. Cells 140, 344 (2015). CrossRef H.Ch. Alan et al. "Light management of tandem solar cells on nanostructured substrates", J. Photon. Energy 7, 027001 (2017) CrossRef

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Wang, Zhiping, Ying Zhou, Tetsuhiko Miyadera, Masayuki Chikamatsu, and Yuji Yoshida. "Constructing Nanostructured Donor/Acceptor Bulk Heterojunctions via Interfacial Templates for Efficient Organic Photovoltaics." ACS Applied Materials & Interfaces 9, no. 50 (December 6, 2017): 43893–901. http://dx.doi.org/10.1021/acsami.7b13989.

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Letertre, Laurie, Roland Roche, Olivier Douhéret, Hailu G. Kassa, Denis Mariolle, Nicolas Chevalier, Łukasz Borowik, et al. "A scanning probe microscopy study of nanostructured TiO2/poly(3-hexylthiophene) hybrid heterojunctions for photovoltaic applications." Beilstein Journal of Nanotechnology 9 (August 1, 2018): 2087–96. http://dx.doi.org/10.3762/bjnano.9.197.

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The nanoscale morphology of photoactive hybrid heterojunctions plays a key role in the performances of hybrid solar cells. In this work, the heterojunctions consist of a nanocolumnar TiO2 surface covalently grafted with a monolayer of poly(3-hexylthiophene) (P3HT) functionalized with carboxylic groups (–COOH). Through a joint analysis of the photovoltaic properties at the nanoscale by photoconductive-AFM (PC-AFM) and surface photovoltage imaging, we investigated the physical mechanisms taking place locally during the photovoltaic process and the correlation to the nanoscale morphology. A down-shift of the vacuum level of the TiO2 surface upon grafting was measured by Kelvin probe force microscopy (KPFM), evidencing the formation of a dipole at the TiO2/P3HT-COOH interface. Upon in situ illumination, a positive photovoltage was observed as a result of the accumulation of photogenerated holes in the P3HT layer. A positive photocurrent was recorded in PC-AFM measurements, whose spatial mapping was interpreted consistently with the corresponding KPFM analysis, offering a correlated analysis of interest from both a theoretical and material design perspective.

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Oladipo, Akeem Adeyemi, and Faisal Suleiman Mustafa. "Bismuth-based nanostructured photocatalysts for the remediation of antibiotics and organic dyes." Beilstein Journal of Nanotechnology 14 (March 3, 2023): 291–321. http://dx.doi.org/10.3762/bjnano.14.26.

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A serious threat to human health and the environment worldwide, in addition to the global energy crisis, is the increasing water pollution caused by micropollutants such as antibiotics and persistent organic dyes. Nanostructured semiconductors in advanced oxidation processes using photocatalysis have recently attracted a lot of interest as a promising green and sustainable wastewater treatment method for a cleaner environment. Due to their narrow bandgaps, distinctive layered structures, plasmonic, piezoelectric and ferroelectric properties, and desirable physicochemical features, bismuth-based nanostructure photocatalysts have emerged as one of the most prominent study topics compared to the commonly used semiconductors (TiO2 and ZnO). In this review, the most recent developments in the use of photocatalysts based on bismuth (e.g., BiFeO3, Bi2MoO6, BiVO4, Bi2WO6, Bi2S3) to remove dyes and antibiotics from wastewater are thoroughly covered. The creation of Z-schemes, Schottky junctions, and heterojunctions, as well as morphological modifications, doping, and other processes are highlighted regarding the fabrication of bismuth-based photocatalysts with improved photocatalytic capabilities. A discussion of general photocatalytic mechanisms is included, along with potential antibiotic and dye degradation pathways in wastewater. Finally, areas that require additional study and attention regarding the usage of photocatalysts based on bismuth for removing pharmaceuticals and textile dyes from wastewater, particularly for real-world applications, are addressed.

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Basyooni, Mohamed A., Shrouk E. Zaki, Nada Alfryyan, Mohammed Tihtih, Yasin Ramazan Eker, Gamal F. Attia, Mücahit Yılmaz, Şule Ateş, and Mohamed Shaban. "Nanostructured MoS2 and WS2 Photoresponses under Gas Stimuli." Nanomaterials 12, no. 20 (October 13, 2022): 3585. http://dx.doi.org/10.3390/nano12203585.

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This study was on the optoelectronic properties of multilayered two-dimensional MoS2 and WS2 materials on a silicon substrate using sputtering physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques. For the first time, we report ultraviolet (UV) photoresponses under air, CO2, and O2 environments at different flow rates. The electrical Hall effect measurement showed the existence of MoS2 (n-type)/Si (p-type) and WS2 (P-type)/Si (p-type) heterojunctions with a higher sheet carrier concentration of 5.50 × 105 cm−2 for WS2 thin film. The IV electrical results revealed that WS2 is more reactive than MoS2 film under different gas stimuli. WS2 film showed high stability under different bias voltages, even at zero bias voltage, due to the noticeably good carrier mobility of 29.8 × 102 cm2/V. WS2 film indicated a fast rise/decay time of 0.23/0.21 s under air while a faster response of 0.190/0.10 s under a CO2 environment was observed. Additionally, the external quantum efficiency of WS2 revealed a remarkable enhancement in the CO2 environment of 1.62 × 108 compared to MoS2 film with 6.74 × 106. According to our findings, the presence of CO2 on the surface of WS2 improves such optoelectronic properties as photocurrent gain, photoresponsivity, external quantum efficiency, and detectivity. These results indicate potential applications of WS2 as a photodetector under gas stimuli for future optoelectronic applications.

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Kumar, Nirmal, Stanislav Haviar, and Petr Zeman. "Three-Layer PdO/CuWO4/CuO System for Hydrogen Gas Sensing with Reduced Humidity Interference." Nanomaterials 11, no. 12 (December 20, 2021): 3456. http://dx.doi.org/10.3390/nano11123456.

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The growing hydrogen industry is stimulating an ongoing search for new materials not only for hydrogen production or storage but also for hydrogen sensing. These materials have to be sensitive to hydrogen, but additionally, their synthesis should be compatible with the microcircuit industry to enable seamless integration into various devices. In addition, the interference of air humidity remains an issue for hydrogen sensing materials. We approach these challenges using conventional reactive sputter deposition. Using three consequential processes, we synthesized multilayer structures. A basic two-layer system composed of a base layer of cupric oxide (CuO) overlayered with a nanostructured copper tungstate (CuWO4) exhibits higher sensitivity than individual materials. This is explained by the formation of microscopic heterojunctions. The addition of a third layer of palladium oxide (PdO) in forms of thin film and particles resulted in a reduction in humidity interference. As a result, a sensing three-layer system working at 150 °C with an equalized response in dry/humid air was developed.

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Fu, Hang-Kuei, Cheng-Liang Cheng, Chun-Hsiung Wang, Tai-Yuan Lin, and Yang-Fang Chen. "Selective Angle Electroluminescence of Light-Emitting Diodes based on Nanostructured ZnO/GaN Heterojunctions." Advanced Functional Materials 19, no. 21 (November 9, 2009): 3471–75. http://dx.doi.org/10.1002/adfm.200900815.

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Georgiadou, D. G., M. Ulmeanu, M. Kompitsas, P. Argitis, and M. Kandyla. "Scalable fabrication of nanostructured p-Si/n-ZnO heterojunctions by femtosecond-laser processing." Materials Research Express 1, no. 4 (October 15, 2014): 045902. http://dx.doi.org/10.1088/2053-1591/1/4/045902.

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Zheng, Feng, Qiang Zhen, Sajid Bashir, and Jingbo Louise Liu. "(Digital Presentation) Ternary Metal Oxide Electrodes Used in Supercapacitor to Improve Emerging Energy Storage." ECS Meeting Abstracts MA2022-01, no. 38 (July 7, 2022): 1685. http://dx.doi.org/10.1149/ma2022-01381685mtgabs.

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Supercapacitors with improved specific capacitance (F g-1), long cycling life, high power (W kg-1), and energy densities (Whkg-1) were fabricated to close the gap between traditional and emerging energy storage materials. We developed responsive supercapacitor electrodes with heterojunctions composed of well-aligned vanadium (V) oxide (V2O5) ribbon arrays and manganese (IV) oxide (MnO2) nanoparticles sphere-network structure. The V2O5 arrays were deposited on the nickel foam substrate using a cost-effective and green hydrothermal chemistry, followed by a MnO2 nano-grafting. The architectural MnO2 modification successfully increased highly reactive interfaces with channels for efficient ion transport. Electrochemical evaluation of this ternary metal oxide system indicated that mesopores and macropores among the MnO2 generated channels that increased electron conduction and shortened ion diffusion pathways. The hybrid electrodes have demonstrated a specific capacitance as high as 788 F g−1 at 5 mV s-1, an improved cyclic steadiness averaged at 92.5 % after 5000 cycles. The charge transfer resistances of these electrodes were lowered to 4.6 Ω and the effective diffusion coefficient of Li+ was 7.90 × 10−9 cm2 s−1. The symmetrical supercapacitor device assembled by the hybrid electrode achieved a high energy density of 138 W h kg-1 at a power density of 450 W kg-1 was achieved and retained at 81.0 W h kg-1 at 9000 W kg-1 after 5000 cycles. The advances in designing nanostructured supercapacitor electrode materials based on these heterojunction arrays enhanced the properties of supercapacitors including specific capacitance, energy density, and cycle stability. Figure 1

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Stavarache, Ionel, Valentin Adrian Maraloiu, Petronela Prepelita, and Gheorghe Iordache. "Nanostructured germanium deposited on heated substrates with enhanced photoelectric properties." Beilstein Journal of Nanotechnology 7 (October 21, 2016): 1492–500. http://dx.doi.org/10.3762/bjnano.7.142.

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Obtaining high-quality materials, based on nanocrystals, at low temperatures is one of the current challenges for opening new paths in improving and developing functional devices in nanoscale electronics and optoelectronics. Here we report a detailed investigation of the optimization of parameters for the in situ synthesis of thin films with high Ge content (50 %) into SiO2. Crystalline Ge nanoparticles were directly formed during co-deposition of SiO2 and Ge on substrates at 300, 400 and 500 °C. Using this approach, effects related to Ge–Ge spacing are emphasized through a significant improvement of the spatial distribution of the Ge nanoparticles and by avoiding multi-step fabrication processes or Ge loss. The influence of the preparation conditions on structural, electrical and optical properties of the fabricated nanostructures was studied by X-ray diffraction, transmission electron microscopy, electrical measurements in dark or under illumination and response time investigations. Finally, we demonstrate the feasibility of the procedure by the means of an Al/n-Si/Ge:SiO2/ITO photodetector test structure. The structures, investigated at room temperature, show superior performance, high photoresponse gain, high responsivity (about 7 AW−1), fast response time (0.5 µs at 4 kHz) and great optoelectronic conversion efficiency of 900% in a wide operation bandwidth, from 450 to 1300 nm. The obtained photoresponse gain and the spectral width are attributed mainly to the high Ge content packed into a SiO2 matrix showing the direct connection between synthesis and optical properties of the tested nanostructures. Our deposition approach put in evidence the great potential of Ge nanoparticles embedded in a SiO2 matrix for hybrid integration, as they may be employed in structures and devices individually or with other materials, hence the possibility of fabricating various heterojunctions on Si, glass or flexible substrates for future development of Si-based integrated optoelectronics.

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Panaitescu, Ana-Maria, Iulia Antohe, Claudiu Locovei, Sorina Iftimie, Ştefan Antohe, Luc Piraux, Mirela Suchea, and Vlad-Andrei Antohe. "Effect of the Cadmium Telluride Deposition Method on the Covering Degree of Electrodes Based on Copper Nanowire Arrays." Applied Sciences 12, no. 15 (August 3, 2022): 7808. http://dx.doi.org/10.3390/app12157808.

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In this work, we report the preparation of nanostructured electrodes based on dense arrays of vertically-aligned copper (Cu) nanowires (NWs) to be subsequently covered by cadmium telluride (CdTe) thin films, with great potential to be used within “substrate”-type photovoltaic cells based on AII-BVI heterojunctions. In particular, the multi-step preparation protocol presented here involves an electrochemical synthesis procedure within a supported anodic aluminum oxide (AAO) nanoporous template for first generating a homogeneous array of vertically-aligned Cu NWs, which are then further embedded within a compact CdTe thin film. In a second stage, we tested three deposition methods (vacuum thermal evaporation, VTE; radio-frequency magnetron sputtering, RF-MS; and electrochemical deposition, ECD) for use in obtaining CdTe layers potentially able to consistently penetrate the previously prepared Cu NWs array. A comparative analysis was performed to critically evaluate the morphological, optical, and structural properties of the deposited CdTe films. The presented results demonstrate that under optimized processing conditions, the ECD approach could potentially allow the cost-effective fabrication of absorber layer/collecting electrode CdTe/Cu nanostructured interfaces that could improve charge collection mechanisms, which in turn could allow the fabrication of more efficient solar cells based on AII-BVI semiconducting compounds.

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Wang, Yong, and Naisen Yu. "Fabrication visible-blind ultraviolet photodetector based on ZnS/GaN heterostructure with fast response." Materials Express 10, no. 5 (May 1, 2020): 629–33. http://dx.doi.org/10.1166/mex.2020.1684.

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In this paper, visible-blind ultraviolet (UV) detectors based on a ZnS/p-GaN heterojunction structure were fabricated. The heterojunction structure was composed of a ZnS nanostructure deposited on a p-GaN/sapphire substrate. The ZnS nanostructured component was obtained via radio-frequency magnetron sputtering. The device based on this ZnS/p-GaN heterojunction structure showed a reproducible, stable, and fast response speed. Therefore, the results demonstrated that the ZnS/p-GaN heterojunction was successfully fabricated using this relatively low-cost method.

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Buyuk, Gonca Ilgu, and Saliha Ilican. "Electrical and photovoltaic properties of p-n heterojunctions obtained using sol gel derived nanostructured ZnO:La films onto p-Si." Superlattices and Microstructures 145 (September 2020): 106605. http://dx.doi.org/10.1016/j.spmi.2020.106605.

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Alahmadi, Nadiyah. "Recent Progress in Photocatalytic Removal of Environmental Pollution Hazards in Water Using Nanostructured Materials." Separations 9, no. 10 (September 22, 2022): 264. http://dx.doi.org/10.3390/separations9100264.

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Water pollution has become a critical issue because of the Industrial Revolution, growing populations, extended droughts, and climate change. Therefore, advanced technologies for wastewater remediation are urgently needed. Water contaminants are generally classified as microorganisms and inorganic/organic pollutants. Inorganic pollutants are toxic and some of them are carcinogenic materials, such as cadmium, arsenic, chromium, cadmium, lead, and mercury. Organic pollutants are contained in various materials, including organic dyes, pesticides, personal care products, detergents, and industrial organic wastes. Nanostructured materials could be potential candidates for photocatalytic reduction and for photodegradation of organic pollutants in wastewater since they have unique physical, chemical, and optical properties. Enhanced photocatalytic performance of nanostructured semiconductors can be achieved using numerous techniques; nanostructured semiconductors can be doped with different species, transition metals, noble metals or nonmetals, or a luminescence agent. Furthermore, another technique to enhance the photocatalytic performance of nanostructured semiconductors is doping with materials that have a narrow band gap. Nanostructure modification, surface engineering, and heterojunction/homojunction production all take significant time and effort. In this review, I report on the synthesis and characterization of nanostructured materials, and we discuss the photocatalytic performance of these nanostructured materials in reducing environmental pollutants.

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Sahoo, Prakash Chandra, Satyabadi Martha, and Kulamani Parida. "Solar Fuels from CO₂ Photoreduction over Nano-Structured Catalysts." Materials Science Forum 855 (May 2016): 1–19. http://dx.doi.org/10.4028/www.scientific.net/msf.855.1.

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The image of CO2 is turning quickly because there are increasing attempts to consider it as resources for hydrocarbon based fuels rather a green house gas. Owing to the limited amount of non-renewable readily available energy sources, the paradigm of energy supply is changing from conventional energy sources to inexhaustible renewable sources such as sunlight, wind, tidal energy. But the current scientific interest is concentrated in the efficient recycling of CO2 from a waste combustion product into a solar fuel by photo reduction method that can be used within the current energy infrastructure. Solar energy as direct solar irradiations is excessively available and it is imperious to utilize it for solar fuel products. In other words, solar to chemical conversion by photo-reduction process is an effective route. Moreover, fuels from solar energy are complementary to solar to electrical energy conversion, but there is still intense research is needed before its successful commercialization. Solar fuels produced from CO2 in comparison with H2 are analyzed and it is seen that these solar-hydrocarbons fuels involves easy transportation and storage than H2 fuel. Photoreduction of CO2 is considered as one of the scientific challenges and has been carried out by different photocatalysts. But the nanostructured photocatalyst owing to their unique optical and electrical property are gaining much attention. Several nanostructured semiconductor photocatalyst such as: metal oxides, heterojunctions, porous materials, layered materials, materials with hierarchical structure, and nanobiocatalysts are acknowledged as good candidate for CO2 photo reduction. This technology not only provides an alternative way to produce the sustainable fuels, but also convert the waste CO2 into valuable chemicals, which is important for keeping our environment clean and sustainable. However, there are still several limitations present in the process of CO2 photoreduction and various strategies have been developed to overcome them. Numerous efforts are required to improve the competence of the photo reduction reaction by developing the novel and efficient photocatalyst with considerable activity, high reaction selectivity. In this chapter, we have summarized several scientific attempts that lead to the design of efficient nanocatalysts for CO2 photo reduction along with their mechanistic pathways.

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Wu, Di, Jun Guo, Zhen-Hua Ge, and Jing Feng. "Facile Synthesis Bi2Te3 Based Nanocomposites: Strategies for Enhancing Charge Carrier Separation to Improve Photocatalytic Activity." Nanomaterials 11, no. 12 (December 14, 2021): 3390. http://dx.doi.org/10.3390/nano11123390.

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Varying structure Bi2Te3-based nanocomposite powders including pure Bi2Te3, Bi2Te3/Bi core−shell, and Bi2Te3/AgBiTe2 heterostructure were synthesized by hydrothermal synthesis using Bi2S3 as the template and hydrazine as the reductant. Successful realization of Bi2Te3-based nanostructures were concluded from XRD, FESEM, and TEM. In this work, the improvement in the performance of the rhodamine B (RhB) decomposition efficiency under visible light was discussed. The Bi2Te3/AgBiTe2 heterostructures revealed propitious photocatalytic performance ca. 90% after 60 min. The performance was over Bi2Te3/Bi core-shell nanostructures (ca. 40%) and more, exceeding pure Bi2Te3 (ca. 5%). The reason could be scrutinized in terms of the heterojunction structure, improving the interfacial contact between Bi2Te3 and AgBiTe2 and enabling retardation in the recombination rate of the photogenerated charge carriers. A credible mechanism of the charge transfer process in the Bi2Te3/AgBiTe2 heterostructures for the decomposition of an aqueous solution of RhB was also explicated. In addition, this work also investigated the stability and recyclability of a Bi2Te3/AgBiTe2 heterojunction nanostructure photocatalyst. In addition, this paper anticipates that the results possess broad potential in the photocatalysis field for the design of a visible light functional and reusable heterojunction nanostructure photocatalyst.

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Pintossi, Chiara, Gabriele Salvinelli, Giovanni Drera, Stefania Pagliara, Luigi Sangaletti, Silvano Del Gobbo, Maurizio Morbidoni, Manuela Scarselli, Maurizio De Crescenzi, and Paola Castrucci. "Direct Evidence of Chemically Inhomogeneous, Nanostructured, Si–O Buried Interfaces and Their Effect on the Efficiency of Carbon Nanotube/Si Photovoltaic Heterojunctions." Journal of Physical Chemistry C 117, no. 36 (August 29, 2013): 18688–96. http://dx.doi.org/10.1021/jp404820k.

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Olivares, Antonio J., Ismael Cosme, Maria Elena Sanchez-Vergara, Svetlana Mansurova, Julio C. Carrillo, Hiram E. Martinez, and Adrian Itzmoyotl. "Nanostructural Modification of PEDOT:PSS for High Charge Carrier Collection in Hybrid Frontal Interface of Solar Cells." Polymers 11, no. 6 (June 11, 2019): 1034. http://dx.doi.org/10.3390/polym11061034.

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In this work, we propose poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) material to form a hybrid heterojunction with amorphous silicon-based materials for high charge carrier collection at the frontal interface of solar cells. The nanostructural characteristics of PEDOT:PSS layers were modified using post-treatment techniques via isopropyl alcohol (IPA). Atomic force microscopy (AFM), Fourier-transform infrared (FTIR), and Raman spectroscopy demonstrated conformational changes and nanostructural reorganization in the surface of the polymer in order to tailor hybrid interface to be used in the heterojunctions of inorganic solar cells. To prove this concept, hybrid polymer/amorphous silicon solar cells were fabricated. The hybrid PEDOT:PSS/buffer/a-Si:H heterojunction demonstrated high transmittance, reduction of electron diffusion, and enhancement of the internal electric field. Although the structure was a planar superstrate-type configuration and the PEDOT:PSS layer was exposed to glow discharge, the hybrid solar cell reached high efficiency compared to that in similar hybrid solar cells with substrate-type configuration and that in textured well-optimized amorphous silicon solar cells fabricated at low temperature. Thus, we demonstrate that PEDOT:PSS is fully tailored and compatible material with plasma processes and can be a substitute for inorganic p-type layers in inorganic solar cells and related devices with improvement of performance and simplification of fabrication process.

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Doroshkevich, Alexander S., Anna S. Zakharova, Boris L. Oksengendler, Andriy I. Lyubchyk, Sergiy I. Lyubchyk, Svitlana B. Lyubchyk, Alisa A. Tatarinova, et al. "The Rectifying Contact of Hydrated Different Size YSZ Nanoparticles for Advanced Electronics." Nanomaterials 12, no. 24 (December 19, 2022): 4493. http://dx.doi.org/10.3390/nano12244493.

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The paper considers the new effects of the nanoscale state of matter, which open up prospects for the development of electronic devices using new physical principles. The contacts of chemically homogeneous nanoparticles of yttrium-stabilized zirconium oxide (ZrO2—x mol% Y2O3, x = 0, 3, 4, 8; YSZ) with different sizes of 7.5 nm and 9 nm; 7.5 nm and 11 nm; and 7.5 nm and 14 nm, respectively, was studied on direct current using nanostructured objects in the form of compacts obtained by high-hydrostatic pressure (HP-compacts of 300MPa). A unique size effect of the nonlinear (rectifying-type contact) dependence of the electrical properties (in the region U < 2.5 V, I ≤ 2.7 mA) of the contact of different-sized YSZ nanoparticles of the same chemical composition is revealed, which indicates the possibility of creating semiconductor structures of a new type (homogeneous electronics). The electronic structure of the near-surface regions of nanoparticles of studied oxide materials and the possibility of obtaining specifically rectifying properties of the contacts were studied theoretically. Models of surface states of the Tamm-type are constructed considering the Coulomb long-range action. The discovered energy variance and its dependence on the curvature of the surface of nanoparticles made it possible to study the conditions for the formation of a contact potential difference in cases of nanoparticles of the same radius (synergistic effect), different radii (doped and undoped variants), as well as to discover the possibility of describing a group of powder particles within the Anderson model. The determined effect makes it possible to solve the problem of diffusion instability of semiconductor heterojunctions and opens up prospects for creating electronic devices with a fundamentally new level of properties for use in various fields of the economy and breakthrough critical technologies.

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Haslinger, Michael J., Dmitry Sivun, Hannes Pöhl, Battulga Munkhbat, Michael Mühlberger, Thomas A. Klar, Markus C. Scharber, and Calin Hrelescu. "Plasmon-Assisted Direction- and Polarization-Sensitive Organic Thin-Film Detector." Nanomaterials 10, no. 9 (September 17, 2020): 1866. http://dx.doi.org/10.3390/nano10091866.

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Utilizing Bragg surface plasmon polaritons (SPPs) on metal nanostructures for the use in optical devices has been intensively investigated in recent years. Here, we demonstrate the integration of nanostructured metal electrodes into an ITO-free thin film bulk heterojunction organic solar cell, by direct fabrication on a nanoimprinted substrate. The nanostructured device shows interesting optical and electrical behavior, depending on angle and polarization of incidence and the side of excitation. Remarkably, for incidence through the top electrode, a dependency on linear polarization and angle of incidence can be observed. We show that these peculiar characteristics can be attributed to the excitation of dispersive and non-dispersive Bragg SPPs on the metal–dielectric interface on the top electrode and compare it with incidence through the bottom electrode. Furthermore, the optical and electrical response can be controlled by the organic photoactive material, the nanostructures, the materials used for the electrodes and the epoxy encapsulation. Our device can be used as a detector, which generates a direct electrical readout and therefore enables the measuring of the angle of incidence of up to 60° or the linear polarization state of light, in a spectral region, which is determined by the active material. Our results could furthermore lead to novel organic Bragg SPP-based sensor for a number of applications.

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24

Reddy B, Kumaar Swamy, Sushmitha Veeralingam, Pramod H. Borse, and Sushmee Badhulika. "1D NiO–3D Fe₂O₃ mixed dimensional heterostructure for fast response flexible broadband photodetector." Nanotechnology 33, no. 23 (March 15, 2022): 235201. http://dx.doi.org/10.1088/1361-6528/ac5838.

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Abstract Conventional heterojunction photodetectors rely on planar junction architecture which suffer from low interfacial contact area, inferior light absorption characteristics and complex fabrication schemes. Heterojunctions based on mixed dimensional nanostructures such as 0D-1D, 1D-2D, 1D-3D etc have recently garnered exceptional research interest owing to their atomically sharp interfaces, tunable junction properties such as enhanced light absorption cross-section. In this work, a flexible broadband UV–vis photodetector employing mixed dimensional heterostructure of 1D NiO nanofibers and 3D Fe2O3 nanoparticles is fabricated. NiO nanofibers were synthesized via economical and scalable electro-spinning technique and made composite with Fe2O3 nanoclusters for hetero-structure fabrication. The optical absorption spectra of NiO nanofibers and Fe2O3 nanoparticles exhibit peak absorption in UV and visible spectra, respectively. The as-fabricated photodetector displays quick response times of 0.09 s and 0.18 s and responsivities of 5.7 mA W−1 (0.03 mW cm−2) and 5.2 mA W−1 (0.01 mW cm−2) for UV and visible spectra, respectively. The fabricated NiO–Fe2O3 device also exhibits excellent detectivity in the order of 1012 jones. The superior performance of the device is ascribed to the type-II heterojunction between NiO–Fe2O3 nanostructures, which results in the localized built-in potential at their interface, that aids in the effective carrier separation and transportation. Further, the flexible photodetector displays excellent robustness when bent over ∼1000 cycles thereby proving its potential towards developing reliable, diverse functional opto-electronic devices.

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25

Li, Dayu, Kai Xu, and Chao Zhang. "Improvement of Photocatalytic Performance by Building Multiple Heterojunction Structures of Anatase–Rutile/BiOI Composite Fibers." Nanomaterials 12, no. 21 (November 5, 2022): 3906. http://dx.doi.org/10.3390/nano12213906.

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In this study, multiple heterojunction structures of anatase–rutile/Bismuth oxyiodide (BiOI) composite fibers are designed by the combined method of electrospinning and hydrothermal techniques. The influence of different Ti/Bi atomic ratios ([Ti/Bi]) on the nanostructures and photocatalytic properties are investigated. It is found that the morphology of BiOI covered on the TiO2 fiber surface changed with [Ti/Bi] from nanosheets to submicron spheres structures. Additionally, the crystallization of the composite fibers including the phases of anatase, rutile, and BiOI is identified, theses phases are in close contact with each other, and the interfacial effects are helpful to form the multiple heterojunctions which lead to blue shifts on the chemical state of Ti. The absorption of visible light has been improved by compositing BiOI on TiO2, while the band gap values of the composite fibers are significantly reduced, which can enhance the generation and separation of electrons and holes. For the case of [Ti/Bi] = 1.57, the photodegradation rate of anatase–rutile/BiOI composite fibers is about 12 times that of pure TiO2. For the photocatalytic mechanism, the synergistic s-type heterojunctions increase the content of active oxides which have a positive effect on the degradation rate.

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26

Zheng, Yuenan, Meihong Fan, Kaiqian Li, Rui Zhang, Xuefeng Li, Ling Zhang, and Zhen-An Qiao. "Ultraviolet-induced Ostwald ripening strategy towards a mesoporous Ga2O3/GaOOH heterojunction composite with a controllable structure for enhanced photocatalytic hydrogen evolution." Catalysis Science & Technology 10, no. 9 (2020): 2882–92. http://dx.doi.org/10.1039/d0cy00303d.

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27

He, Bo, Jing Xu, HuanPo Ning, Hao Xiong, HuaiZhong Xing, and YuMing Qin. "Characterization of Nanostructured n-ZnO/p-Si Heterojunction Prepared by a Simple Sol–Gel Method." International Journal of Nanoscience 15, no. 04 (August 2016): 1650014. http://dx.doi.org/10.1142/s0219581x16500149.

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The nanostructured ZnO film was prepared on a texturized Si wafer by a simple sol–gel method to fabricate n-ZnO/p-Si heterojunction photoelectric device. The novel sol–gel method is cheap and convenient. The structural, optical and electrical properties of the nanostructured ZnO film were studied by XRD, SEM, XPS, PL, UV–Vis spectrophotometer and Hall effect measurement. The current–voltage (I–V) curve of nanostructured ZnO/p-Si heterojunction device shows good rectifying behavior. Good photoelectric behavior is obtained.

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Kumari, Priyanka, Nupur Bahadur, Lingxue Kong, Luke A. O’Dell, Andrea Merenda, and Ludovic F. Dumée. "Engineering Schottky-like and heterojunction materials for enhanced photocatalysis performance – a review." Materials Advances 3, no. 5 (2022): 2309–23. http://dx.doi.org/10.1039/d1ma01062j.

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29

Choi, Byeonghoon, Dongwoo Shin, Hee-Seung Lee, and Hyunjoon Song. "Nanoparticle design and assembly for p-type metal oxide gas sensors." Nanoscale 14, no. 9 (2022): 3387–97. http://dx.doi.org/10.1039/d1nr07561f.

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30

Lin, Haowei, Ao Jiang, Shibo Xing, Lun Li, Wenxi Cheng, Jinling Li, Wei Miao, Xuefei Zhou, and Li Tian. "Advances in Self-Powered Ultraviolet Photodetectors Based on P-N Heterojunction Low-Dimensional Nanostructures." Nanomaterials 12, no. 6 (March 10, 2022): 910. http://dx.doi.org/10.3390/nano12060910.

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Self-powered ultraviolet (UV) photodetectors have attracted considerable attention in recent years because of their vast applications in the military and civil fields. Among them, self-powered UV photodetectors based on p-n heterojunction low-dimensional nanostructures are a very attractive research field due to combining the advantages of low-dimensional semiconductor nanostructures (such as large specific surface area, excellent carrier transmission channel, and larger photoconductive gain) with the feature of working independently without an external power source. In this review, a selection of recent developments focused on improving the performance of self-powered UV photodetectors based on p-n heterojunction low-dimensional nanostructures from different aspects are summarized. It is expected that more novel, dexterous, and intelligent photodetectors will be developed as soon as possible on the basis of these works.

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31

Joshi, Siddharth, Mrunmaya Mudigere, L. Krishnamurthy, and G. L. Shekar. "Growth of Horizontal Nanopillars of CuO on NiO/ITO Surfaces." Journal of Nanoscience 2014 (August 28, 2014): 1–6. http://dx.doi.org/10.1155/2014/635308.

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We have demonstrated hydrothermal synthesis of rectangular pillar-like CuO nanostructures at low temperature (~60°C) by selective growth on top of NiO porous structures film deposited using chemical bath deposition method at room temperature using indium tin oxide (ITO) coated glass plate as a substrate. The growth of CuO not only filled the NiO porous structures but also formed the big nanopillars/nanowalls on top of NiO surface. These nanopillars could have significant use in nanoelectronics devices or can also be used as p-type conducting wires. The present study is limited to the surface morphology studies of the thin nanostructured layers of NiO/CuO composite materials. Structural, morphological, and absorption measurement of the CuO/NiO heterojunction were studied using state-of-the-art techniques like X-ray diffraction (XRD), transmission electron microscopy (SEM), atomic force microscopy (AFM), and UV spectroscopy. The CuO nanopillars/nanowalls have the structure in order of (5 ± 1.0) μm × (2.0 ± 0.3) μm; this will help to provide efficient charge transport in between the different semiconducting layers. The energy band gap of NiO and CuO was also calculated based on UV measurements and discussed.

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32

Zagorac, Dejan, Jelena Zagorac, Milan Pejić, Branko Matović, and Johann Christian Schön. "Band Gap Engineering of Newly Discovered ZnO/ZnS Polytypic Nanomaterials." Nanomaterials 12, no. 9 (May 8, 2022): 1595. http://dx.doi.org/10.3390/nano12091595.

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We report on a new class of ZnO/ZnS nanomaterials based on the wurtzite/sphalerite architecture with improved electronic properties. Semiconducting properties of pristine ZnO and ZnS compounds and mixed ZnO1−xSx nanomaterials have been investigated using ab initio methods. In particular, we present the results of our theoretical investigation on the electronic structure of the ZnO1−xSx (x = 0.20, 0.25, 0.33, 0.50, 0.60, 0.66, and 0.75) nanocrystalline polytypes (2H, 3C, 4H, 5H, 6H, 8H, 9R, 12R, and 15R) calculated using hybrid PBE0 and HSE06 functionals. The main observations are the possibility of alternative polytypic nanomaterials, the effects of structural features of such polytypic nanostructures on semiconducting properties of ZnO/ZnS nanomaterials, the ability to tune the band gap as a function of sulfur content, as well as the influence of the location of sulfur layers in the structure that can dramatically affect electronic properties. Our study opens new fields of ZnO/ZnS band gap engineering on a multi-scale level with possible applications in photovoltaics, light-emitting diodes, laser diodes, heterojunction solar cells, infrared detectors, thermoelectrics, or/and nanostructured ceramics.

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33

Lu, Yang-Ming, Chi-Feng Tseng, Bing-Yi Lan, and Chia-Fen Hsieh. "Fabrication of Graphene/Zinc Oxide Nano-Heterostructure for Hydrogen Sensing." Materials 14, no. 22 (November 17, 2021): 6943. http://dx.doi.org/10.3390/ma14226943.

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In this study, hydrogen (H2) and methane (CH4) were used as reactive gases, and chemical vapor deposition (CVD) was used to grow single-layer graphene on a copper foil substrate. The single-layer graphene obtained was transferred to a single-crystal silicon substrate by PMMA transfer technology for the subsequent growth of nano zinc oxide. The characteristics of CVD-deposited graphene were analyzed by a Raman spectrometer, an optical microscope, a four-point probe, and an ultraviolet/visible spectrometer. The sol–gel method was applied to prepare the zinc oxide seed layer film with the spin-coating method, with methanol, zinc acetate, and sodium hydroxide as the precursors for growing ZnO nanostructures. On top of the ZnO seed layer, a one-dimensional zinc oxide nanostructure was grown by a hydrothermal method at 95 °C, using a zinc nitrate and hexamethylenetetramine mixture solution. The characteristics of the nano zinc oxide were analyzed by scanning electron microscope(SEM),x-ray diffractometer(XRD), and Raman spectrometer. The obtained graphene/zinc oxide nano-heterostructure sensor has a sensitivity of 1.06 at a sensing temperature of 205 °C and a concentration of hydrogen as low as 5 ppm, with excellent sensing repeatability. The main reason for this is that the zinc oxide nanostructure has a large specific surface area, and many oxygen vacancy defects exist on its surface. In addition, the P–N heterojunction formed between the n-type zinc oxide and the p-type graphene also contributes to hydrogen sensing.

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34

Novák, J., A. Laurenčíková, P. Eliáš, S. Hasenöhrl, M. Sojková, J. Kováč, and J. Kováč. "Investigation of a nanostructured GaP/MoS₂ p-n heterojunction photodiode." AIP Advances 12, no. 6 (June 1, 2022): 065004. http://dx.doi.org/10.1063/5.0089842.

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We report on the properties of a GaP/MoS2 heterojunction prepared on a nanocone (NC)-structured GaP substrate and a planar GaP substrate. The nanocone-structured GaP substrate was prepared by the growth of GaP NCs at gold seeds on a ⟨111⟩B GaP substrate at 650 °C by metal organic vapor phase epitaxy. At this growth temperature, most NCs exhibited a hexagonal symmetry with six heavily facetted sides that contained numerous facets, ledges, and edges with a large surface area. A thin Mo layer was deposited on both types of GaP substrates by direct current magnetron sputtering. The Mo layer was then sulfurated at 700 °C and turned into a MoS2 layer. Electrical and optical characterization gave evidence that a PN heterojunction formed between GaP and MoS2 during the sulfuration process. The spectral response measurement showed two separate regions between 400 and 550 nm linked with the generation of carriers in GaP and between 550 and 1100 nm associated with the generation of carriers in the MoS2 layer. The planar GaP/MoS2 heterojunction generated a lower photocurrent compared with the GaP/MoS2 heterojunction that formed on the nanocone-structured GaP substrate. The results support theoretical assumptions that edge rich substrates can help to increase the quality of deposited 2D materials.

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35

Brabec, Christoph J., Thomas Nann, and Sean E. Shaheen. "Nanostructured p–n Junctions for Printable Photovoltaics." MRS Bulletin 29, no. 1 (January 2004): 43–47. http://dx.doi.org/10.1557/mrs2004.16.

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AbstractBy controlling the morphology of organic and inorganic semiconductors on a molecular scale, nanoscale p–n junctions can be generated in a bulk composite. Such a composite is typically called a bulk heterojunction composite, which can be considered as one virtual semiconductor combining the electrical and optical properties of the individual components. Solar cells are one attractive application for bulk heterojunction composites. Conjugated polymers or oligomers are the favorite p-type semiconducting class for these composites, while for the n-type semiconductor, inorganic nanoparticles as well as organic molecules have been investigated. Due to the solubility of the individual components, printing techniques are used to fabricate them.

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36

Majhi, Sanjit Manohar, Hu-Jun Lee, Ha-Nui Choi, Ha-Young Cho, Jin-Soo Kim, Cheul-Ro Lee, and Yeon-Tae Yu. "Construction of novel hybrid PdO–ZnO p–n heterojunction nanostructures as a high-response sensor for acetaldehyde gas." CrystEngComm 21, no. 34 (2019): 5084–94. http://dx.doi.org/10.1039/c9ce00710e.

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37

Hong, Yang, Jingchao Zhang, and Xiao Cheng Zeng. "Thermal contact resistance across a linear heterojunction within a hybrid graphene/hexagonal boron nitride sheet." Physical Chemistry Chemical Physics 18, no. 35 (2016): 24164–70. http://dx.doi.org/10.1039/c6cp03933b.

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38

S. Mofarah, Sajjad, Luisa Schreck, Claudio Cazorla, Xiaoran Zheng, Esmaeil Adabifiroozjaei, Constantine Tsounis, Jason Scott, et al. "Highly catalytically active CeO2−x-based heterojunction nanostructures with mixed micro/meso-porous architectures." Nanoscale 13, no. 14 (2021): 6764–71. http://dx.doi.org/10.1039/d0nr08097g.

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The present work reports a template-free approach to fabricate 3D mesoporous CeO_2−x-based heterojunction nanostructures comprised of holey 2D nanosheets with outstanding densities of active sites that deliver excellent CO conversion performance.

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39

Murzin, Serguei P. "Formation of ZnO/CuO Heterostructures Based on Quasi-One-Dimensional Nanomaterials." Applied Sciences 13, no. 1 (December 30, 2022): 488. http://dx.doi.org/10.3390/app13010488.

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Nanostructured metal oxides are of great interest both for advanced research and for a wide range of applications that contribute to the increasing demands of electronics, photonics, catalysis, sensorics, and other high-tech industries and are being actively researched and developed. One-dimensional nanocrystal arrays of copper and zinc oxides have become prominent in optoelectronic devices and energy conversion systems. However, although desirable improved properties have been demonstrated, the morphology of materials containing copper and zinc oxide nanowires is extremely sensitive to synthesis conditions and difficult to control. Studies focused on the morphology control of such quasi-one-dimensional materials are not numerous, so the consideration of this issue is still relevant. The characteristics of devices based on such oxide materials can be improved by taking advantage of nanoheterojunctions. A special feature is the possibility of forming a polycrystalline heterojunction in a system of semiconductors belonging to different crystalline syngonies. Currently, much attention is devoted to developing reliable methods of obtaining such nanomaterials, including those, based on processes exploiting novel physical effects. Possibilities of synthesis by pulse-periodic laser irradiation of arrays of quasi-one-dimensional ZnO nanostructures with varying micromorphology on metallic substrates, as well as the creation of ZnO/CuO heterostructures based on ZnO nanowires, were considered. The main distinguishing feature of this approach was the use of laser-induced vibrations to intensify diffusion processes in the solid phase of metallic materials as compared to the simple effects of laser beam heating. Expanding the area of application of the advanced method of creating oxide heterostructures requires a detailed and comprehensive study of new possibilities used to form structures with improved physical properties.

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40

Ghimire, R. R., B. P. Pokhrel, S. P. Gupta, L. P. Joshi, and K. B. Rai. "Optical and Electrical Properties of Homo and Heterojunction Formed by the ZnO/FTO and CuO/ZnO/FTO Nanostructures." Journal of Nepal Physical Society 9, no. 1 (August 25, 2023): 73–82. http://dx.doi.org/10.3126/jnphyssoc.v9i1.57600.

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The most common materials used to create electrical and optoelectronic devices for a variety of applications including transistor, sensor and detector are semiconductor nanostructures. Combining the nanostructures can result semiconductor homostructure and heterostructure. The homojunction of ZnO/FTO and heterojunction of CuO/ZnO/FTO coated glass substrate are formed using spray pyrolysis technique. The optical band gap for the FTO, ZnO, ZnO/FTO and CuO/ZnO/FTO films calculated using data from UV-visible spectroscopy are 3.629 eV, 3.236 eV, 3.113 eV and 1.456 eV respectively. The observed ohmic behavior of ZnO/FTO homojunction is due to the close band gap of FTO (i.e. Eg = 3.629 eV) and ZnO (Eg = 3.236 eV) whereas the non-ohmic behavior of CuO/ZnO/FTO heterojunction is due to the significant different in band gap energy of CuO (i.e. Eg = 1.456 eV) and ZnO (Eg = 3.236 eV). The photocurrent for ZnO/FTO homojunction increases from 232 μA to 350 μA for visible light illumination and from 232 μA to 400 μA for UV light illumination at bias voltage of 2.5 V. There is no significantly changed in the threshold voltage in visible region. For the CuO/ZnO/FTO heterojunction, the photocurrent increases from 280 μA to 390 μA for visible illumination and from 280 μA to 480 μA for UV illumination at 2.5 V. The enhancement of channel current in both sample (i.e. homojunction and heterojunction) under visible illumination is due to detrapping the charge carriers from mid gap states and released to the conduction band. The large enhancement of photocurrent under UV illumination is due to band gap absorption. Threshold voltage for CuO/ZnO/FTO non-ohmic device is shifted negatively from 1 V to 0 V with increasing the frequency of incident radiation. It suggests that the heterojunction formed by CuO/ZnO/FTO structure is applicable for broad band photo detector.

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41

Melnichenko, Ivan, Eduard Moiseev, Natalia Kryzhanovskaya, Ivan Makhov, Alexey Nadtochiy, Nikolay Kalyuznyy, Valeriy Kondratev, and Alexey Zhukov. "Submicron-Size Emitters of the 1.2–1.55 μm Spectral Range Based on InP/InAsP/InP Nanostructures Integrated into Si Substrate." Nanomaterials 12, no. 23 (November 27, 2022): 4213. http://dx.doi.org/10.3390/nano12234213.

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We study photoluminescence of InP/InAsP/InP nanostructures monolithically integrated to a Si(100) substrate. The InP/InAsP/InP nanostructures were grown in pre-formed pits in the silicon substrate using an original approach based on selective area growth and driven by a molten alloy in metal–organic vapor epitaxy method. This approach provides the selective-area synthesis of the ordered emitters arrays on Si substrates. The obtained InP/InAsP/InP nanostructures have a submicron size. The individual InP/InAsP/InP nanostructures were investigated by photoluminescence spectroscopy at room temperature. The tuning of the emission line in the spectral range from 1200 nm to 1550 nm was obtained depending on the growth parameters. These results provide a path for the growth on Si(100) substrate of position-controlled heterojunctions based on InAs1−xPx for nanoscale optical devices operating at the telecom band.

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42

Karbalaei Akbari, Mohammad, Nasrin Siraj Lopa, and Serge Zhuiykov. "Atomic Layer Deposition of Ultra-Thin Crystalline Electron Channels for Heterointerface Polarization at Two-Dimensional Metal-Semiconductor Heterojunctions." Coatings 13, no. 6 (June 3, 2023): 1041. http://dx.doi.org/10.3390/coatings13061041.

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Atomic layer deposition (ALD) has emerged as a promising technology for the development of the next generation of low-power semiconductor electronics. The wafer-scaled growth of two-dimensional (2D) crystalline nanostructures is a fundamental step toward the development of advanced nanofabrication technologies. Ga2O3 is an ultra-wide bandgap metal oxide semiconductor for application in electronic devices. The polymorphous Ga2O3 with its unique electronic characteristics and doping capabilities is a functional option for heterointerface engineering at metal-semiconductor 2D heterojunctions for application in nanofabrication technology. Plasma-enhanced atomic layer deposition (PE-ALD) enabled the deposition of ultra-thin nanostructures at low-growth temperatures. The present study used the PE-ALD process for the deposition of atomically thin crystalline ß-Ga2O3 films for heterointerface engineering at 2D metal-semiconductor heterojunctions. Via the control of plasma gas composition and ALD temperature, the wafer-scaled deposition of ~5.0 nm thick crystalline ß-Ga2O3 at Au/Ga2O3-TiO2 heterointerfaces was achieved. Material characterization techniques showed the effects of plasma composition and ALD temperature on the properties and structure of Ga2O3 films. The following study on the electronic characteristics of Au/Ga2O3-TiO2 2D heterojunctions confirmed the tunability of this metal/semiconductor polarized junction, which works as functional electron channel layer developed based on tunable p-n junctions at 2D metal/semiconductor interfaces.

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Huang, Shaoying, Naisen Yu, Tiyun Wang, and Jinpeng Li. "Simple fabrication of UV photo-detector based on NiO/ZnO structure grown by hydrothermal process." Functional Materials Letters 11, no. 02 (April 2018): 1850045. http://dx.doi.org/10.1142/s1793604718500455.

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A simple two-step aqueous method was employed to grow NiO nanostructures on ZnO/sapphire at low temperature. The obtained NiO nanostructures were uniformly distributed on the surface of ZnO/sapphire substrates and showed sheet-like structures. Meanwhile, ultraviolet (UV) photodetector based on NiO/ZnO heterojunction was fabricated by a simple way. The obtained UV detector based on the NiO nanosheets/ZnO heterostructure showed excellent UV sensing properties due to the increased surface and local [Formula: see text]-[Formula: see text] junction area. It will facilitate greatly the fabrication of large-scale NiO/ZnO heterostructure with relatively low cost at remarkably low temperature.

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44

Faisal, A. D., W. K. Kalef, E. T. Salim, and F. H. Alsultany. "Synthesis of CuO/SnO2 NPs on quartz substrate for temperature sensors application." Journal of Ovonic Research 18, no. 2 (April 12, 2022): 205–12. http://dx.doi.org/10.15251/jor.2022.182.205.

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Temperature sensor of p-CuO/n-SnO2 heterojunction was successfully fabricated and investigated. SnO2 nanostructure was firstly synthesized via chemical vapor deposition. Followed by a top layer of CuO nanoparticles was deposited on SnO2 by drop cast method. The SnO2 film was analyzed via x-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD confirms the formation of the SnO2 nanstructure .The SEM reveals the SnO2 nanoparticles agglomerated together forming a cauliflowers-like nanostructure with a calculated particle size of 17nm. The temperature response corresponding to the relative variation of sensor resistance (ΔR) to a given temperature was measured. It was found that the present sensor has a high sensitivity of 0.56%/°C. Temperature sensor p-CuO/n-SnO2 heterojunction was found to be quite promising material in the temperature range of 25-200⁰ C.

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Kalita, Golap, Matsushima Masahiro, Wakita Koichi, and Masayoshi Umeno. "Nanostructured morphology of P3HT:PCBM bulk heterojunction solar cells." Solid-State Electronics 54, no. 4 (April 2010): 447–51. http://dx.doi.org/10.1016/j.sse.2009.11.010.

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Pinto, Alexandre H., Andre E. Nogueira, Cleocir J. Dalmaschio, Iago N. Frigini, Jéssica C. de Almeida, Mateus M. Ferrer, Olivia M. Berengue, Rosana A. Gonçalves, and Vagner R. de Mendonça. "Doped Tin Dioxide (d-SnO2) and Its Nanostructures: Review of the Theoretical Aspects, Photocatalytic and Biomedical Applications." Solids 3, no. 2 (June 2, 2022): 327–60. http://dx.doi.org/10.3390/solids3020024.

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Nanomaterials based on metal oxides are extensively studied for several applications due to their versatility. Improvements in their performances can be obtained due to specific structural modifications. One possible modification is by doping the crystal structure, which can affect the materials structure and properties, especially in nanosized particles. Electronic features are among the properties that can be modified through the doping process, consequently morphological and optical parameters can also be controlled by this process. In this sense, this review presents some modifications to tin dioxide (SnO2), one the most studied materials, mainly through the doping process and their impact on several properties. The article starts by describing the SnO2 structural features and the computational models used to explain the role of the doping process on these features. Based on those models, some applications of doped SnO2, such as photocatalytic degradation of pollutants, CO2 reduction, and desulfurization of fossil fuels are presented and discussed. Additionally, the review describes many biological applications related to antimicrobial activity for doped SnO2 and its nanostructures. Although most of the examples presented in this article are based on the doped SnO2, it also presents examples related to SnO2 composites with other nanomaterials forming heterojunctions. The metal oxides SnO2, doped-SnO2 and their nanostructures are promising materials, with results reported in many fields presented in this review, such as theoretical and computational chemistry, environmental remediation, nanoparticle morphology control, fossil fuels improvement, and biomedical applications. Although widely explored, there are still fields for innovation and advances with tin dioxide nanostructures, for example, in transparent conducting oxides, in forensics as materials for latent fingerprints visualization, and sensors in medicine for detection of exhaled volatile organic compounds. Therefore, this article aims to be a reference regarding correlating the doping processes and the properties presented by the SnO2 nanostructures.

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Zagorac, Dejan, Jelena Zagorac, J. Christian Schön, Nemanja Stojanović, and Branko Matović. "ZnO/ZnS (hetero)structures: ab initio investigations of polytypic behavior of mixed ZnO and ZnS compounds." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 74, no. 6 (November 16, 2018): 628–42. http://dx.doi.org/10.1107/s2052520618014099.

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The range of feasible ZnO/ZnS polytypes has been explored, predicting alternative structural arrangements compared with previously suggested or observed structural forms of ZnO/ZnS compounds, including bulk crystal structures, various nanostructures, heterostructures and heterojunctions. All calculations were performed ab initio using density functional theory–local density approximation and hybrid Heyd–Scuseria–Ernzerhof functionals. Specifically, pure ZnO and ZnS compounds and mixed ZnO1–x S x compounds (x = 0.20, 0.25, 0.33, 0.50, 0.60, 0.66 and 0.75) are investigated and a multitude of possible stable polytypes for ZnO/ZnS compounds creating new possibilities for synthesis of new materials with improved physical and chemical properties are identified.

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Yang, Peidong. "The Chemistry and Physics of Semiconductor Nanowires." MRS Bulletin 30, no. 2 (February 2005): 85–91. http://dx.doi.org/10.1557/mrs2005.26.

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AbstractThe following article is based on the Outstanding Young Investigator Award presentation given by Peidong Yang of the University of California, Berkeley, on April 14, 2004, at the Materials Research Society Spring Meeting in San Francisco.Yang was cited for “innovative synthesis of a broad range of nanowires and nanowireheterostructure materials, and the discovery of optically induced lasing in individual nanowire devices.” One-dimensional nanostructures are of both fundamental and technological interest.They not only exhibit interesting electronic and optical properties associated with their low dimensionality and the quantum confinement effect, but they also represent critical components in potential nanoscale devices. In this article, the vapor–liquid–solid crystal growth mechanism will be briefly introduced for the general synthesis of nanowires of different compositions, sizes, and orientation. Unique properties, including light-emission and thermoelectricity, will be discussed. In addition to the recent extensive studies on “single-component” nanowires, of increasing importance is incorporating different interfaces and controlling doping profiles within individual single-crystalline nanowires. Epitaxial growth plays a significant role in fabricating such nanowire heterostructures. Recent research on superlattice nanowires and other nanostructures with horizontal junctions will be presented. The implication of these heterojunction nanowires in light-emission and energy conversion will be discussed. Ways to assemble these one-dimensional nanostructures will also be presented.

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MOSTEFA KARA, Selma, and Abdelhalim BENMANSOUR. "Properties of High Efficiency Nanostructured Copper Indium Gallium Selenide Thin Film Solar Cells." Electrotehnica, Electronica, Automatica 70, no. 1 (March 15, 2022): 3–12. http://dx.doi.org/10.46904/eea.22.70.1.1108001.

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Nowadays it is widely acknowledged that solar photovoltaic energy is one of the preferred options for sustainable management of the future energy needs of the world. For this, new technological processes, known as second and third generations, based on the use of thin films and nanomaterials, have recently been developed in order to reduce the cost of solar cells. Over the past few years, the yield of second-generation Cu(In, Ga)Se2 thin-film cells has exceeded 22 %. It was found that as nanostructured materials such as nanowire arrays often have a higher light absorption rate than thin films, they can therefore be used. This article aims to design and model nanostructured CIGS thin film solar cells based on indium tin oxide (ITO) nanowires. Modelling provides information on the operation of CIGS solar cells, as well as on the mechanisms of absorption and electric charge transport. The purpose of this work is to evaluate the electrical and optical characteristics (ISC, VOC, FF, η) of a ZnO/CdS/CIGS heterojunction thin film structure. Thus, an optimum efficiency of 17.57 % and a form factor of 76.56 % were achieved. Afterwards, the Mo film rear contact was replaced with ITO nanowires which were introduced into the CIGS-based solar cell. The results indicated that the solar cells under study exhibited very good photovoltaic performance, with an efficiency of 21.26 %. It is worth noting that this performance is higher than that of the corresponding CIGS thin film cells. In addition, the large active surface area of the ITO nanowire electrode and the short distance that the charge must travel helped to improve charge collection in the nanostructure. This would certainly increase the short circuit current ISC, and consequently the electrical efficiency. The simulation was based on the low-field mobility model, and on Shockley-Read-Hall (SRH) and Auger carrier transport and recombination models which may be activated in ATLAS-SILVACO (2D).

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Yun, Hyun‐Sung, Byung‐wook Park, Yong Chan Choi, Jino Im, Tae Joo Shin, and Sang Il Seok. "Efficient Nanostructured TiO 2 /SnS Heterojunction Solar Cells." Advanced Energy Materials 9, no. 35 (August 5, 2019): 1901343. http://dx.doi.org/10.1002/aenm.201901343.

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Journal articles on the topic 'Heterojunctions - Nanostructured Materials'

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