Los autores agradecen a Svilen Bobev por su ayuda con los espectros de difracción de rayos X y K. Booksh de asistencia con el equipo Sputter.

1. Síntesis de árbol-como ZnO / CdSSe nanoestructuras <ol><li> El pretratamiento y el oro de recubrimiento de sustratos de zafiro NOTA: La película de oro actúa como un catalizador en el crecimiento de los nanocables de ZnO. <ol><li> diapositivas de zafiro limpio (un avión, 10 x 10 x 1 mm) en el 99,5% de etanol con 5 min de tratamiento con ultrasonidos para preparar el sustrato de Au pulverización catódica. </li><li> Depositar a 10 nm (± 2 nm) de espesor de película de oro sobre los portaobjetos de zafiro con un dispositivo de recubrimiento por pulverización catódica y objetivo de oro. </li></ol></li><li> Síntesis de nanocables de ZnO NOTA: La etapa de sonicación 1.2.2 resultados en una ZnO homogénea y carbono (/ C ZnO) mezcla. Después de mezclar, la mezcla cambia a un color gris. La etapa de compactación 1.2.3 asegura que el aire no está presente en la mezcla y que el ZnO y el carbono están en estrecho contacto. Después de CVD, una película blanca de nanocables de ZnO debe ser depositado sobre el sustrato, lado que mira hacia el barco. <ol><li> Mezclar 1 g de ZnO y nanopowder activcarbono ated (proporción en masa de 50:50) en 10 ml de etanol al 99,5% y mezclar bien con una espátula. </li><li> Sonicar la mezcla en un baño de agua a 20 ºC durante 30 minutos, y luego se seca en un horno durante ~ 5 horas a 80 ºC. </li><li> Colocar la mezcla ZnO / C en un bote de aluminio y compacto bien con una espátula. </li><li> Colocar los portaobjetos de zafiro recubiertas de oro en la parte superior de la embarcación de alúmina, con el lado recubierto de oro hacia abajo. Coloque el barco de alúmina en el centro del tubo de cuarzo en un horno de tubo horizontal. </li><li> Purgar el tubo de cuarzo durante 1 hora con Ar a un caudal de 40 sccm a temperatura ambiente (RT). Aumentar la temperatura de RT a 900 ºC a una velocidad de 80 ºC / min y mantener constante el caudal de argón. </li><li> Mantenga la temperatura a 900 ° C durante 2 horas. Abrir el tubo de cuarzo en ambos extremos mediante la eliminación de las entradas de gas tapón de goma y dejar que entre aire en el tubo para proporcionar oxígeno para la reacción. </li><li> Mantenga la temperatura de reacción a 900 ° C durante 3 horas con el rutapones bber quitados. Enfriar a temperatura ambiente a una velocidad de 10 ºC / min. </li><li> Tome el barco y la corredera fuera del horno. </li></ol></li><li> La deposición de ramas CdSSe en nanocables de ZnO NOTA: El barco de alúmina de CdS / Se fue representada en el centro del tubo de cuarzo. Los nanocables de ZnO preparados se enfrentan hacia arriba y eran de 10 cm abajo de la embarcación. Después de este segundo CVD, un / película de color amarillo anaranjado, que es la nanoestructura ZnO / CdSSe, debe ser depositado en la diapositiva. <ol><li> Mezclar 0,5 g de CdS y CdSe (CdS / Se) y polvo (fracción de masa de 50:50) y colocar la mezcla en un bote de alúmina. Compactar bien la mezcla. </li><li> Coloque el bote de alúmina de CdS / SE y la muestra de ZnO nanocables preparado previamente en el tubo de cuarzo. </li><li> Purgar el tubo con Ar a un caudal de 40 sccm a RT durante 1 hr. Aumentar la temperatura de reacción a 820 ºC a una velocidad de 80 ºC / min. Mantenga la temperatura a 820 ºC durante 30 min. </li><li> Enfriar a RT auna velocidad de 10 ºC / min. Tome el barco y la corredera fuera del horno. </li></ol></li><li> Síntesis de las muestras de control: ZnO y CdSSe nanocables <ol><li> Sintetizar nanocables de ZnO como en la sección 1.2, en las mismas condiciones experimentales. </li><li> Sintetizar nanocables CdSSe como en la sección 1.3, en las mismas condiciones experimentales, con la misma cantidad de CdS y composición CdSe, pero con una, tobogán zafiro recubierto de oro limpia como sustrato en lugar de la corredera de ZnO-depositado. </li></ol></li></ol> 2. Caracterización morfológica y cristalográfica <ol><li> Montar la muestra en la etapa SEM con una abrazadera y colocar la muestra en la cámara de vacío del instrumento SEM. Tomar imágenes de SEM en el modo de alta resolución con una distancia de trabajo de 12,0 mm a una tensión de 3 kV y una ampliación de entre 3,000X y 10.000X 11,12. </li><li> Tomar datos EDS con la misma muestra utilizando el detector de rayos X a la misma distancia de trabajo de12.0 mm. Poner el instrumento a modo de análisis y ajuste el voltaje a 20 kV, lo que resulta en una corriente de 20 a 40 mu 13. </li><li> Recoger los espectros de difracción de rayos X en un difractómetro de polvo de rayos X usando radiación filtrada Cu Ka (λ = 1,5418 Å) 11,12. </li></ol> 3. PL espectroscopia de emisión y Medidas de por vida PL Tiempo de resolver NOTA: Los espectros de PL y recuento de fotones individuales correlacionado con el tiempo (TCSPC) mediciones en RT se llevaron a cabo usando un amplificado Ti: oscilador de zafiro después de segunda generación armónica (SHG), produciendo un tren de 50 impulsos FSEC centradas en una longitud de onda de 400 nm y con una potencia de salida de 1,76 mW 14. <ol><li> Fijar la muestra en un soporte de muestras que posiciona la cara de muestra hasta el láser y al detector. Alinear el láser para centrarse en la muestra. Medir los espectros de emisión PL de las muestras de 500-nm a longitudes de onda 900 nm utilizando un espectrómetro de fibra. </li><li> Use un detector de fotón único (avalanche fotodiodo o célula fotoeléctrica) para medir los tiempos de vida PL tiempo de resolverse con un filtro de vidrio de color y un filtro de interferencia de paso de banda de 500 o 650 nm. </li><li> Insertar ZnO, CdSSe, o ZnO / CdSSe se desliza en el soporte de muestra. Medir los nanocables de ZnO puro con el filtro de paso de banda de 500 nm y las muestras CdSSe o ZnO / CdSSe con un filtro de paso de banda de 650 nm. </li><li> Utilice un contador de fotón único correlacionado con el tiempo o un osciloscopio rápido para medir los tiempos de vida de decaimiento de fluorescencia con resolución temporal. </li></ol>

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Datos y cifras en este artículo se citan en la bibliografía de la nanotecnología por Li et al. 17.

La alineación vertical de nanocables de ZnO (tallos) se basa en el crecimiento epitaxial sobre el sustrato. Nanocables de ZnO crecen preferentemente a lo largo de la &lt;0001&gt; dirección que coincide con la periodicidad de la a-plano de zafiro 12. Por lo tanto, el tipo y la calidad del sustrato son muy importantes. Diferentes espesores de la capa de oro sobre el substrato, de 5 nm a 20 nm, se han probado y no mostró diferencias significativas en el crecimiento de nanocables de ZnO. La longitud de los nan...

ZnO es un semiconductor II-VI que ofrece un intervalo de banda (BG) de 3,3 eV, una alta movilidad de electrones, y un 1,2 energía de enlace gran excitón. Se trata de un material semiconductor abundante, con una gran cantidad de aplicaciones presentes y futuras en dispositivos ópticos, células solares, y fotocatálisis. Sin embargo, ZnO es transparente, lo que limita su aplicación en la gama espectral visible. Por lo tanto, materiales absorbentes de luz visible, tales como semiconductores estrecha brecha de 3, 4 moléculas de colorante, y polímeros fotosensibles 5, con frecuencia han sido empleados para sensibilizar ZnO a la absorción de la luz visible. CdS (BG 2.43 eV) y CdSe (BG 1.76 eV) son comunes semiconductores II-VI-gap estrecho y se han investigado intensamente. Los parámetros de BG y de celosía de la aleación ternaria CdSSe se pueden ajustar mediante la variación de las relaciones molares de los componentes de VI 6,7. nanocompuestos ZnO / CdSSe se han reportado para dar lugar a photov eficienteconversión de energía oltaic 8,9. La combinación de la vía de transporte de electrones eficiente de los nanocables de ZnO alineados verticalmente hacia un sustrato con la mejora de la absorción de luz visible de las ramas CdSSe condujo a la transferencia eficiente de electrones entre el tallo y las ramas 9,10. Por lo tanto, se sintetizó una nueva nanoestructura ZnO / CdSSe en forma de árbol, donde nanocables de ZnO alineados verticalmente están decoradas con ramas CdSSe. Este material compuesto puede actuar como un bloque de construcción para los nuevos dispositivos de conversión de energía solar. Este protocolo describe cómo se cultivan las matrices de nanocables de ZnO sobre un sustrato de zafiro mediante la deposición química de vapor de un solo paso (CVD) a partir de polvos de ZnO y C, siguiendo un procedimiento que ha sido previamente publicado 11. Tras el crecimiento de los nanocables de ZnO, un segundo paso de CVD se emplea para crecer ramas CdSSe en los nanocables de ZnO. Empleamos de difracción de rayos X en polvo (XRD), microscopía electrónica de barrido (SEM), yespectroscopia de rayos X de energía dispersiva (EDS) para medir la estructura cristalina, morfología y composición de los nanotrees ZnO / CdSSe (NTs). El mecanismo de transferencia de propiedades ópticas y portador de carga entre las ramas y el tallo había sido investigada por la fotoluminiscencia (PL) y espectroscopia de mediciones de toda la vida PL tiempo de resolverse.

<table><tbody><tr><td>ZnO</td><td>Sigma Aldrich</td><td>1314-13-2</td><td></td></tr><tr><td>Activated Carbon</td><td>Alfa</td><td>231-153-3</td><td></td></tr><tr><td>CdSe</td><td>Sigma Aldrich</td><td>1306-24-7</td><td></td></tr><tr><td>CdS</td><td>Sigma Aldrich</td><td>1306-23-6</td><td></td></tr><tr><td>Sapphire</td><td>MTI</td><td>2SP</td><td>a-plane, 10 &amp;times; 10 &amp;times; 1 mm</td></tr><tr><td>Furnace</td><td>Lindberg Blue M</td><td>SSP</td><td></td></tr><tr><td>Scanning electron microscope</td><td>Hitachi</td><td>S5700</td><td>assembled with an Oxford Inca X-act detector</td></tr><tr><td>X-ray powder diffractometer</td><td>Rigaku</td><td>MiniFlex</td><td>filtered Cu K&amp;alpha; radiation (&amp;lambda;=1.5418&amp;nbsp;&amp;Aring;)</td></tr><tr><td>Amplified Ti:sapphire oscillator</td><td>Coherent Mantis</td><td>Coherent Legend-Elite</td><td></td></tr><tr><td>Single photon detection module</td><td>ID Quantique</td><td>ID-100</td><td></td></tr><tr><td>Sputter coater</td><td>Cressington</td><td>308</td><td>assembled with gold target</td></tr><tr><td>Fiber probe spectrometer</td><td>Photon Control</td><td>SPM-002</td><td></td></tr><tr><td>Colored Glass Filter</td><td>Thorlabs</td><td>FGB37-A - &amp;Oslash;25 mm BG40</td><td>AR Coated: 350 - 700&amp;nbsp;nm</td></tr><tr><td>Compressed argon gas</td><td>Keen</td><td>7440-37-1</td><td></td></tr></tbody></table>

synthesis of hierarchical zno/cdsse heterostructure nanotrees

Un procedimiento de deposición de vapor químico de dos etapas se emplea aquí para preparar jerárquicos ZnO / CdSSe hetero-nanoestructuras en forma de árbol. Las estructuras se componen de ramas CdSSe cultivadas en nanocables de ZnO que están alineadas verticalmente sobre un sustrato de zafiro transparente. La morfología se midió a través de microscopía electrónica de barrido. La estructura cristalina se determinó por análisis de difracción de polvo de rayos X. Tanto el ZnO tallo y las ramas CdSSe tener una estructura de cristal predominantemente wurtzita. La relación molar de S y de Se en las ramas CdSSe se midió por espectroscopia de rayos X de dispersión de energía. Las ramas CdSSe dan lugar a una fuerte absorción de la luz visible. Fotoluminiscencia (PL) espectroscopía demostró que el tallo y las ramas forman una heterounión de tipo II. mediciones de toda la vida PL mostraron una disminución en el tiempo de vida de la emisión de los árboles, en comparación con la emisión de ZnO individuo tallos o ramas CdSSe e indicar la transferencia de carga rápida entre CdSSe y ZnO. el verticamente alineado ZnO se debe proporcionar una vía de transporte de electrones directa al sustrato y permitir la separación de la carga eficiente después de fotoexcitación por la luz visible. La combinación de las propiedades mencionadas anteriormente hace ZnO / CdSSe nanotrees candidatos prometedores para aplicaciones en células solares, la fotocatálisis, y dispositivos opto-electrónicos.

La Figura 1 muestra el mecanismo de crecimiento de ZnO / CdSSe NT. El procedimiento consistió en un proceso catalítico de vapor-líquido-sólido (VLS) seguido de un crecimiento no catalítica vapor-sólido (VS). En el primer paso VLS, ZnO y C reaccionan en la atmósfera Ar, resultando en Zn metálico y óxido de carbono. Zn se disuelve posteriormente en el precursor de oro sobre el sustrato de zafiro. nanocables de ZnO crecen desde el Zn disuelto y oxígeno residual. E...

Watch this Scientific Journal Video about Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees at JoVE.com

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

A continuación, preparamos y caracterizar nuevos jerárquicos nanoestructuras de ZnO / CdSSe forma de árbol, donde las ramas CdSSe se cultivan en nanocables de ZnO alineados verticalmente. Los nanotrees resultantes son un material potencial para la conversión de energía solar y otros dispositivos optoelectrónicos.

Síntesis del jerárquica ZnO / CdSSe heteroestructura Nanotrees

A two-step chemical vapor deposition procedure is here employed to prepare tree-like hierarchical ZnO/CdSSe hetero-nanostructures. The structures are ...

synthesis-of-hierarchical-znocdsse-heterostructure-nanotrees

Research

JoVE Journal

Chemistry

10.0K vistas.  University of Delaware.  A continuación, preparamos y caracterizar nuevos jerárquicos nanoestructuras de ZnO / CdSSe forma de árbol, donde las ramas CdSSe se cultivan en nanocables de ZnO alineados verticalmente. Los nanotrees resultantes son un material potencial para la conversión de energía solar y otros dispositivos optoelectrónicos. 

Video: Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Harvesting Solar Energy by Means of Charge-Separating Nanocrystals and Their Solids

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials offering a superior control over the spatial distribution of charge carriers across material interfaces. As this study demonstrates, a combination of donor-acceptor nanocrystal (NC) domains in a single nanoparticle can lead to the realization of efficient photocatalytic1-5 materials, while a layered assembly of donor- and acceptor-like nanocrystals films gives rise to photovoltaic materials.
Initially the paper focuses on the synthesis of composite inorganic nanocrystals, comprising linearly stacked ZnSe, CdS, and Pt domains, which jointly promote photoinduced charge separation. These structures are used in aqueous solutions for the photocatalysis of water under solar radiation, resulting in the production of H2 gas. To enhance the photoinduced separation of charges, a nanorod morphology with a linear gradient originating from an intrinsic electric field is used5. The inter-domain energetics are then optimized to drive photogenerated electrons toward the Pt catalytic site while expelling the holes to the surface of ZnSe domains for sacrificial regeneration (via methanol). Here we show that the only efficient way to produce hydrogen is to use electron-donating ligands to passivate the surface states by tuning the energy level alignment at the semiconductor-ligand interface. Stable and efficient reduction of water is allowed by these ligands due to the fact that they fill vacancies in the valence band of the semiconductor domain, preventing energetic holes from degrading it. Specifically, we show that the energy of the hole is transferred to the ligand moiety, leaving the semiconductor domain functional. This enables us to return the entire nanocrystal-ligand system to a functional state, when the ligands are degraded, by simply adding fresh ligands to the system4.
To promote a photovoltaic charge separation, we use a composite two-layer solid of PbS and TiO2 films. In this configuration, photoinduced electrons are injected into TiO2 and are subsequently picked up by an FTO electrode, while holes are channeled to a Au electrode via PbS layer6. To develop the latter we introduce a Semiconductor Matrix Encapsulated Nanocrystal Arrays (SMENA) strategy, which allows bonding PbS NCs into the surrounding matrix of CdS semiconductor. As a result, fabricated solids exhibit excellent thermal stability, attributed to the heteroepitaxial structure of nanocrystal-matrix interfaces, and show compelling light-harvesting performance in prototype solar cells7.

A general strategy for the development of charge-separating semiconductor nanocrystal composites deployable for solar energy production is presented. We show that assembly of donor-acceptor nanocrystal domains in a single nanoparticle geometry gives rise to a photocatalytic function, while bulk-heterojunctions of donor-acceptor nanocrystal films can be used for photovoltaic energy conversion.

Captación de energía solar por medio de carga de separación nanocristales y sus sólidos

Conjoining different semiconductor materials in a single nano-composite provides synthetic means for the development of novel optoelectronic materials ...

Investigación

Ingeniería

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

Química

Ultrahigh Density Array of Vertically Aligned Small-molecular Organic Nanowires on Arbitrary Substrates

In recent years &pi;-conjugated organic semiconductors have emerged as the active material in a number of diverse applications including large-area, low-cost displays, photovoltaics, printable and flexible electronics and organic spin valves. Organics allow (a) low-cost, low-temperature processing and (b) molecular-level design of electronic, optical and spin transport characteristics. Such features are not readily available for mainstream inorganic semiconductors, which have enabled organics to carve a niche in the silicon-dominated electronics market. The first generation of organic-based devices has focused on thin film geometries, grown by physical vapor deposition or solution processing. However, it has been realized that organic nanostructures can be used to enhance performance of above-mentioned applications and significant effort has been invested in exploring methods for organic nanostructure fabrication.	
A particularly interesting class of organic nanostructures is the one in which vertically oriented organic nanowires, nanorods or nanotubes are organized in a well-regimented, high-density array. Such structures are highly versatile and are ideal morphological architectures for various applications such as chemical sensors, split-dipole nanoantennas, photovoltaic devices with radially heterostructured "core-shell" nanowires, and memory devices with a cross-point geometry. Such architecture is generally realized by a template-directed approach. In the past this method has been used to grow metal and inorganic semiconductor nanowire arrays. More recently &pi;-conjugated polymer nanowires have been grown within nanoporous templates. However, these approaches have had limited success in growing nanowires of technologically important &pi;-conjugated small molecular weight organics, such as tris-8-hydroxyquinoline aluminum (Alq3), rubrene and methanofullerenes, which are commonly used in diverse areas including organic displays, photovoltaics, thin film transistors and spintronics.	
Recently we have been able to address the above-mentioned issue by employing a novel "centrifugation-assisted" approach. This method therefore broadens the spectrum of organic materials that can be patterned in a vertically ordered nanowire array. Due to the technological importance of Alq3, rubrene and methanofullerenes, our method can be used to explore how the nanostructuring of these materials affects the performance of aforementioned organic devices. The purpose of this article is to describe the technical details of the above-mentioned protocol, demonstrate how this process can be extended to grow small-molecular organic nanowires on arbitrary substrates and finally, to discuss the critical steps, limitations, possible modifications, trouble-shooting and future applications.

We report a simple method for fabricating an ultrahigh density array of vertically ordered small-molecular organic nanowires. This method allows for synthesis of complex heterostructured hybrid nanowire geometries, which can be inexpensively grown on arbitrary substrates. These structures have potential applications in organic electronics, optoelectronics, chemical sensing, photovoltaics and spintronics.

Ultra Alta Densidad conjunto de nanocables orgánicos pequeña moleculares verticalmente alineados sobre sustratos arbitrarias

In  recent years &pi;-conjugated  organic semiconductors have emerged as the active material in a number of  diverse applications including large-area, ...

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO3 (001) and DyScO3 (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca2Nb3O10- nanosheets were used, prepared by delamination of their layered parent compound HCa2Nb3O10. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.

Various procedures are outlined to prepare atomically defined templates for epitaxial growth of complex oxide thin films. Chemical treatments of single crystalline SrTiO3 (001) and DyScO3 (110) substrates were performed to obtain atomically smooth, single terminated surfaces. Ca2 Nb3 O10- nanosheets were used to create atomically defined templates on arbitrary substrates.

Plantillas Atómicamente definidos para crecimiento epitaxial de óxido complejo Películas Delgadas

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain ...

Preparation of ZnO Nanorod/Graphene/ZnO Nanorod Epitaxial Double Heterostructure for Piezoelectrical Nanogenerator by Using Preheating Hydrothermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we describe a one-step fabrication technique to synthesis freestanding ZnO nanorod/graphene/ZnO nanorod double heterostructure. The preparation of the double heterostructure is performed by using thermal chemical vapor deposition (CVD) and preheating hydrothermal technique. In addition, the morphological properties were characterized by using the scanning electron microscopy (SEM). The utility of freestanding double heterostructure is demonstrated by fabricating the piezoelectric nanogenerator. The electrical output is improved up to 200% compared to that of a single heterostructure owing to the coupling effect of the piezoelectricity between the arrays of ZnO nanorods on the top and bottom of graphene. This unique double heterostructure have a tremendous potential for applications of electrical and optoelectrical devices where the high number density and specific surface area of nanorod are needed, such as pressure sensor, immuno-biosensor and dye-sensitized solar cells.

One-step fabrication method for obtaining freestanding epitaxial double heterostructure is presented. This approach could achieve ZnO coverage with a higher number density than that of the epitaxial single heterostructure, leading to a piezoelectric nanogenerator with an increased output electrical performance.

Preparación de ZnO nanorod / grafeno / ZnO nanorod epitaxialLa heteroestructura doble para piezoeléctricas nanogenerador mediante precalentamiento Hidrotermal

Well-aligned ZnO nanostructures have been intensively studied over the last decade for remarkable physical properties and enormous applications. Here, we ...

Well-aligned Vertically Oriented ZnO Nanorod Arrays and their Application in Inverted Small Molecule Solar Cells

This manuscript describes how to design and fabricate efficient inverted solar cells, which are based on a two-dimensional conjugated small molecule (SMPV1) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), by utilizing ZnO nanorods (NRs) grown on a high quality Al-doped ZnO (AZO) seed layer. The inverted SMPV1:PC71BM solar cells with ZnO NRs that grew on both a sputtered and sol-gel processed AZO seed layer are fabricated. Compared with the AZO thin film prepared by the sol-gel method, the sputtered AZO thin film exhibits better crystallization and lower surface roughness, according to X-ray diffraction (XRD) and atomic force microscope (AFM) measurements. The orientation of the ZnO NRs grown on a sputtered AZO seed layer shows better vertical alignment, which is beneficial for the deposition of the subsequent active layer, forming better surface morphologies. Generally, the surface morphology of the active layer mainly dominates the fill factor (FF) of the devices. Consequently, the well-aligned ZnO NRs can be used to improve the carrier collection of the active layer and to increase the FF of the solar cells. Moreover, as an anti-reflection structure, it can also be utilized to enhance the light harvesting of the absorption layer, with the power conversion efficiency (PCE) of solar cells reaching 6.01%, higher than the sol-gel based solar cells with an efficiency of 4.74%.

This manuscript describes how to design and fabricate efficient inverted SMPV1:PC71BM solar cells with ZnO nanorods (NRs) grown on a high quality Al-doped ZnO (AZO) seed layer. The well-aligned vertically oriented ZnO NRs exhibit high crystalline properties. The power conversion efficiency of solar cells can reach 6.01%.

Bien alineados verticalmente orientado a ZnO Nanorod matrices y su aplicación en invertida pequeña molécula de las células solares

This manuscript describes how to design and fabricate efficient inverted solar cells, which are based on a two-dimensional conjugated small molecule ...

A Standard and Reliable Method to Fabricate Two-Dimensional Nanoelectronics

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D materials is still in nascent stages, scientists cannot fully rely on traditional semiconductor techniques for related research. Delicate processes from locating the materials to electrode definition need to be well controlled. In this article, a universal fabrication protocol required in manufacturing nanoscale electronics, such as 2D quasi-heterojunction bipolar transistors (Q-HBT), and 2D back-gated transistors are demonstrated. This protocol includes the determination of material position, electron beam lithography (EBL), metal electrode definition, et al. A step by step narrative of the fabrication procedures for these devices are also presented. Furthermore, results show that each of the fabricated devices has achieved high performance with high repeatability. This work reveals a comprehensive description of process flow for preparing 2D nano-electronics, enables the research groups to access this information, and pave the way toward future electronics.

The article aims to introduce a standard and reliable fabrication procedure for the development of future low dimensional nanoelectronics.

Un método estándar y fiable para la fabricación nanoelectrónica bidimensional

Two-dimensional (2D) materials have attracted huge attention due to their unique properties and potential applications. Since wafer scale synthesis of 2D ...

Fabrication of Schottky Diodes on Zn-polar BeMgZnO/ZnO Heterostructure Grown by Plasma-assisted Molecular Beam Epitaxy

Heterostructure field effect transistors (HFETs) utilizing a two dimensional electron gas (2DEG) channel have a great potential for high speed device applications. Zinc oxide (ZnO), a semiconductor with a wide bandgap (3.4 eV) and high electron saturation velocity has gained a great deal of attention as an attractive material for high speed devices. Efficient gate modulation, however, requires high-quality Schottky contacts on the barrier layer. In this article, we present our Schottky diode fabrication procedure on Zn-polar BeMgZnO/ZnO heterostructure with high density 2DEG which is achieved through strain modulation and incorporation of a few percent Be into the MgZnO-based barrier during growth by molecular beam epitaxy (MBE). To achieve high crystalline quality, nearly lattice-matched high-resistivity GaN templates grown by metal-organic chemical vapor deposition (MOCVD) are used as the substrate for the subsequent MBE growth of the oxide layers. To obtain the requisite Zn-polarity, careful surface treatment of GaN templates and control over the VI/II ratio during the growth of low temperature ZnO nucleation layer are utilized. Ti/Au electrodes serve as Ohmic contacts, and Ag electrodes deposited on the O2 plasma pretreated BeMgZnO surface are used for Schottky contacts.

Attainment of high-quality Schottky contacts is imperative for achieving efficient gate modulation in heterostructure field effect transistors (HFETs). We present the fabrication methodology and characteristics of Schottky diodes on Zn-polar BeMgZnO/ZnO heterostructures with high-density two dimensional electron gas (2DEG), grown by plasma-assisted molecular beam epitaxy on GaN templates.

Fabricación de diodos de Schottky en Zn-polar heteroestructura de BeMgZnO/ZnO por Epitaxy de viga Molecular asistida por Plasma

Heterostructure field effect transistors (HFETs) utilizing a two dimensional electron gas (2DEG) channel have a great potential for high speed device ...

Growth of Gold Dendritic Nanoforests on Titanium Nitride-coated Silicon Substrates

In this study, a high-power impulse magnetron sputtering system is used to coat a flat and firm titanium nitride (TiN) film on silicon (Si) wafers, and a fluoride-assisted galvanic replacement reaction (FAGRR) is employed for the rapid and easy deposition of gold dendritic nanoforests (Au DNFs) on the TiN/Si substrates. Scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy patterns of TiN/Si and Au DNFs/TiN/Si samples validate that the synthesis process is accurately controlled. Under the reaction conditions in this study, the thickness of the Au DNFs increases linearly to 5.10 &#177; 0.20 &#181;m within 15 min of the reaction. Therefore, the employed synthesis procedure is a simple and rapid approach for preparing Au DNFs/TiN/Si composites.

This study presents a feasible procedure for synthesizing gold dendritic nanoforests on titanium nitride/silicon substrates. The thickness of gold dendritic nanoforests increases linearly within 15 min of a synthesis reaction.

Crecimiento de nanoformas dendríticas de oro en sustratos de silicio recubiertos de nitruro de titanio

In this study, a high-power impulse magnetron sputtering system is used to coat a flat and firm titanium nitride (TiN) film on silicon (Si) wafers, and a ...

Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations

Computational tools based on density-functional theory (DFT) enable the exploration of the qualitatively new, experimentally attainable nanoscale compounds for a targeted application. Theoretical simulations provide a profound understanding of the intrinsic electronic properties of functional materials. The goal of this protocol is to search for photocatalyst candidates by computational dissection. Photocatalytic applications require suitable band gaps, appropriate band edge positions relative to the redox potentials. Hybrid functionals can provide accurate values of these properties but are computationally expensive, whereas the results at the Perdew-Burke-Ernzerhof (PBE) functional level could be effective for suggesting strategies for band structure engineering via electric field and tensile strain aiming to enhance the photocatalytic performance. To illustrate this, in the present manuscript, the DFT based simulation tool VASP is used to investigate the band alignment of nanocomposites in combinations of nanotubes and nanoribbons in the ground state. To address the lifetime of photogenerated holes and electrons in the excited state, nonadiabatic dynamics calculations are needed.

Calculations performed by the Vienna Ab initio Simulation Package can be used to identify the intrinsic electronic properties of nanoscale materials and predict the potential water-splitting photocatalysts.