Os autores agradecem Svilen Bobev por sua ajuda com os espectros de DRX e K. Booksh de assistência com o equipamento de pulverização catódica coater.

1. Síntese de árvore-como ZnO / CdSSe Nanoestruturas <ol><li> O pré-tratamento e ouro revestimento de substratos de safira NOTA: O filme de ouro actua como um catalisador no crescimento dos nanofios de ZnO. <ol><li> lâminas de safira limpa (a-avião, 10 × 10 × 1 mm) em 99,5% de etanol com 5 min de sonicação para preparar o substrato para Au pulverização catódica. </li><li> Depositar a 10 nm (± 2 nm) filme -grossa de ouro nas lâminas de safira com um revestidor por crepitação e alvo de ouro. </li></ol></li><li> Síntese de nanofios de ZnO NOTA: O passo de sonicação 1.2.2 resulta em uma ZnO homogênea e carbono (/ C ZnO) mistura. Após a mistura, a mistura muda para uma cor cinza. A etapa de compactação 1.2.3 garante que nenhum ar está presente na mistura e que o ZnO e carbono estão em contato próximo. Depois de DCV, uma película branca de nanofios de ZnO deve ser depositado sobre o substrato, lado voltado para baixo para o barco. <ol><li> Misture 1 g de nanopowder ZnO e activated carbono (fracção de massa de 50:50) em 10 ml de etanol a 99,5% e agita-se bem com uma espátula. </li><li> Sonicar a mistura num banho de água a 20 ºC durante 30 min, e em seguida secá-lo numa estufa durante ~ 5 horas a 80 ºC. </li><li> Coloque a mistura de ZnO / C numa barquinha de alumina e compacta-lo bem com uma espátula. </li><li> Colocar as lâminas de safira revestido a ouro no topo da barquinha de alumina, com o lado revestido a ouro voltado para baixo. Coloque a barquinha de alumina no centro do tubo de quartzo num forno tubular horizontal. </li><li> Purga-se o tubo de quartzo, durante 1 h com atmosfera de Ar a uma taxa de fluxo de 40 sccm à temperatura ambiente (RT). Aumentar a temperatura de RT a 900 ° C a uma taxa de 80 ° C / min e manter constante a taxa de fluxo de árgon. </li><li> Mantenha a temperatura a 900 ° C durante 2 horas. Abrir o tubo de quartzo em ambas as extremidades, removendo as entradas de gás e de rolha de borracha que o ar entre o tubo para fornecer oxigénio para a reacção. </li><li> Manter a temperatura da reacção a 900 ° C durante 3 h com o RUrolhas bber removido. Arrefecer até à TA, a uma taxa de 10 ° C / min. </li><li> Pegue o barco e deslizar para fora do forno. </li></ol></li><li> Deposição de ramos CdSSe em nanofios de ZnO NOTA: O barco de alumina do CDS / Se foi apresentada no centro do tubo de quartzo. Os nanofios de ZnO foram preparadas virada para cima, e foram de 10 cm a jusante a partir do barco. Após esta segunda DCV, uma laranja / filme amarelo, que é a nanoestrutura ZnO / CdSSe, deve ser depositada sobre a lâmina. <ol><li> Misture 0,5 g de CDs e CdSe (CDS / Se) bem pó (fração de massa de 50:50) e coloque a mistura em um barco de alumina. Compactar bem a mistura. </li><li> Coloque o barco alumina do CDS / SE e da amostra de ZnO nanofio previamente preparado no tubo de quartzo. </li><li> Purga-se o tubo com atmosfera de Ar a uma taxa de fluxo de 40 sccm à TA durante 1 h. Aumentar a temperatura de reacção para 820 ° C a uma taxa de 80 ° C / min. Mantenha a temperatura a 820 ° C durante 30 min. </li><li> Arrefecer até à RT emuma taxa de 10 ° C / min. Pegue o barco e deslizar para fora do forno. </li></ol></li><li> Síntese das amostras de controlo: ZnO e CdSSe nanofios <ol><li> Sintetizar nanofios de ZnO como na secção 1.2, sob as mesmas condições experimentais. </li><li> Sintetizar nanofios CdSSe como no ponto 1.3, sob as mesmas condições experimentais, com a mesma quantidade de CDs e composição CdSe, mas com, um slide de safira revestido a ouro limpo como substrato em vez do slide depositados-ZnO. </li></ol></li></ol> 2. morfológica e cristalográfica Caracterização <ol><li> Montar a amostra na fase SEM com uma braçadeira e colocar a amostra na câmara de vácuo do instrumento SEM. Tome imagens de MEV no modo de alta resolução com uma distância de trabalho de 12,0 mm a uma tensão de 3 kV e uma ampliação entre 3,000X e 10.000 vezes 11,12. </li><li> Tome dados de EDS com a mesma amostra usando o detector de raios-X à mesma distância de trabalho de12.0 mm. Ajustar o instrumento para o modo de análise e ajustar a tensão de 20 kV, resultando em uma corrente de 20 a 40 uA 13. </li><li> Recolhe espectros de DRX, em um difractómetro de pó por raios-X usando radiação Cu Ka filtrada (λ = 1,5418 Â) 11,12. </li></ol> 3. PL Espectroscopia de Emissão e Medidas Lifetime PL resolvida no tempo Observação: Os espectros de PL e contagem de fotão único correlacionados em tempo (TCSPC) medições a RT foram realizadas utilizando um amplificado Ti: oscilador safira após a segunda geração de harmónica (SHG), a produção de um trem de 50 impulsos FSEC centrado no comprimento de onda de 400 nm e com uma potência de saída de 1,76 mW 14. <ol><li> Fixar a amostra num suporte de amostras que posiciona a face da amostra até o laser e o detector. Alinhar o laser para focar a amostra. Medir o espectro de emissão PL das amostras a partir de 500 nm, comprimentos de onda de 900 nm utilizando um espectrómetro de fibra. </li><li> Use um detector de fóton único (avalanche foto diodo ou phototube) para medir vidas PL resolvidas no tempo com um filtro de vidro de cor e um filtro de interferência de banda de 500 ou 650 nm. </li><li> Inserir ZnO, CdSSe ou ZnO / CdSSe desliza no suporte da amostra. Meça os nanofios de ZnO puros com o filtro de banda de 500 nm e as amostras CdSSe ou ZnO / CdSSe com um filtro de banda de 650 nm. </li><li> Usar um contador de fóton único correlacionados em tempo ou um osciloscópio rápido para medir o tempo de vida de fluorescência de decaimento resolvidas no tempo. </li></ol>

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Dados e números neste artigo são citados na literatura em nanotecnologia por Li et al. 17.

O alinhamento vertical das nanofios de ZnO (hastes) baseia-se no crescimento epitaxial sobre o substrato. Nanofios de ZnO crescer preferencialmente ao longo da &lt;0001&gt; direção que combina com a periodicidade de um plano de safira 12. Portanto, o tipo e a qualidade do substrato são muito importantes. Diferentes espessuras do revestimento de ouro no substrato, a partir de 5 nm a 20 nm, foram testados e mostraram nenhuma diferença significativa no crescimento de nanofios de ZnO. O comprimento dos nanofi...

ZnO é um semicondutor II-VI com um gap (BG) de 3,3 eV, uma alta mobilidade de elétrons e um 1,2 energia de ligação grande éxciton. É um material semicondutor abundante com uma infinidade de aplicações presentes e futuras em dispositivos ópticos, células solares, e fotocatálise. No entanto, ZnO é transparente, o que limita a sua aplicação na gama espectral visível. Portanto, materiais absorventes de luz visível, tais como semicondutores narrow-gap 3, moléculas de corante 4, e polímeros fotossensíveis 5, têm sido frequentemente utilizados para sensibilizar ZnO a absorção de luz visível. CDs (BG 2,43 eV) e CdSe (BG 1,76 eV) são comuns II-VI semicondutores narrow-gap e têm sido intensamente investigados. Os parâmetros de BG e gelosia da liga ternária CdSSe pode ser ajustado através da variação das razões molares dos componentes VI 6,7. nanocompósitos ZnO / CdSSe ter sido relatada como resultando em photov eficienteconversão de energia oltaic 8,9. Combinando a via de transporte de elétrons eficiente de nanofios de ZnO alinhados verticalmente contra um substrato com a absorção de luz visível melhoria dos ramos CdSSe levou à transferência de elétrons eficiente entre o caule e ramos 9,10. Assim, sintetizamos uma nova árvore-como ZnO / CdSSe nanoestrutura, onde nanofios de ZnO alinhados verticalmente são decorados com ramos CdSSe. Este material compósito pode actuar como um bloco de construção de novos dispositivos de conversão de energia solar. Este protocolo descreve como matrizes de nanofios de ZnO são cultivados num substrato de safira por deposição de vapor químico de um passo (DCV) a partir de pós de ZnO e C, seguindo um procedimento que foi anteriormente publicado a 11. Seguindo o crescimento de nanofios de ZnO, um segundo passo de DCV é empregue para crescer em ramos CdSSe os nanofios de ZnO. Empregamos de difracção de raios-X em pó (XRD), microscopia electrónica de varrimento (SEM), eespectroscopia de raios-X de energia dispersiva (EDS) para medir a estruturas de cristal, morfologia e composição das nanotrees ZnO / CdSSe (NTs). O mecanismo de transferência de propriedades ópticas e carga transportadora entre os ramos e caule foram investigados por fotoluminescência (PL) espectroscopia e as medições ao longo da vida PL resolvidas no tempo.

<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

Um procedimento de deposição de vapor químico de duas etapas é aqui empregue para preparar hierárquicos ZnO / CdSSe hetero-nanoestruturas de árvore. As estruturas são compostas por ramos CdSSe cultivadas em nanofios de ZnO que estão verticalmente alinhados sobre um substrato de safira transparente. A morfologia foi medida através de microscopia eletrônica de varredura. A estrutura cristalina foi determinada por análise de difracção de pó de raios-X. Tanto o ZnO caule e ramos CdSSe tem uma estrutura de cristal predominantemente wurtzita. A proporção molar de S e Se, nos ramos CdSSe foi medido por espectroscopia de raios X de energia dispersiva. Os ramos CdSSe resultar em forte absorção de luz visível. Fotoluminescência (PL) espectroscopia mostraram que o caule e dos ramos formam um heterojunï¿½o tipo II. medições vida PL mostraram uma diminuição no tempo de vida de emissão das árvores, quando em comparação com a emissão de ZnO hastes individuais ou ramos CdSSe e indicar rápida transferência de carga entre CdSSe e ZnO. o verticamente alinhados ZnO hastes proporcionar uma via de transporte de electrões directamente para o substrato e para permitir a separação de carga eficiente após fotoexcitação pela luz visível. A combinação das propriedades acima mencionadas faz ZnO / CdSSe nanotrees candidatos promissores para aplicações em células solares, fotocatálise, e dispositivos opto-electrónicos.

A Figura 1 mostra o mecanismo de crescimento de ZnO / NTs CdSSe. O procedimento envolveu um processo catalítico de vapor-líquido-sólido (VLS), seguido por um crescimento de vapor-sólido não catalítico (VS). No primeiro passo VLS, ZnO e C reagem na atmosfera de Ar, resultando em Zn metálico e óxido de carbono. Zn é subsequentemente dissolvido no precursor de ouro no substrato de safira. nanofios de ZnO crescer a partir do Zn dissolvido e oxigênio residual. No se...

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

Synthesis of Hierarchical ZnO/CdSSe Heterostructure Nanotrees

Aqui, nós preparar e caracterizar novos hierárquicos nanoestruturas de ZnO / CdSSe árvore-like, onde ramos CdSSe são cultivadas em nanofios de ZnO alinhados verticalmente. Os nanotrees resultantes são um material potencial para a conversão de energia solar e outros dispositivos opto-electrónicos.

Síntese de hierárquicos ZnO / CdSSe heterostructure 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

Universidad San Sebastian

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JoVE Journal

Chemistry

10.0K visualizações.  University of Delaware.  Aqui, nós preparar e caracterizar novos hierárquicos nanoestruturas de ZnO / CdSSe árvore-like, onde ramos CdSSe são cultivadas em nanofios de ZnO alinhados verticalmente. Os nanotrees resultantes são um material potencial para a conversão de energia solar e outros dispositivos opto-electrónicos. 

Vídeo: 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.

Captação de energia solar por meio da carga de separação de nanocristais e seus sólidos

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

Engenharia

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.

Semeado Síntese de CdSe / CdS Rod e tetrápodes Nanocristais

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 Density Array of alinhados verticalmente Nanofios orgânicos pequeno-moleculares sobre substratos Arbitrárias

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.

Templates atomicamente definidos para crescimento epitaxial do Complexo Óxido Filmes Finos

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.

Preparação de ZnO nanorod / Grafeno / ZnO nanorod Epitaxial Duplo heterostructure para piezoelétricos nanogenerator usando pré-aquecimento Hydrothermal

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%.

Bem alinhados verticalmente orientado ZnO Nanorod matrizes e sua aplicação em invertida pequena molécula 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.

Um método padrão e confiável para fabricar 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.

Fabricação de diodos de Schottky na Zn-polar BeMgZnO/ZnO Heterostructure cultivadas por Epitaxia de feixe Molecular assistido 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.

Crescimento de nanoformas dendríticos de ouro em substratos de silício revestidos de nitreto de titânio

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.