这项工作得到了西班牙科学和创新部的支持, 其部分原因是 TEC2015-74329-金 (AEI/菲德、欧盟)、TEC2016-79898-C6-1-R (AEI/菲德、欧盟) 和 TEC-2013-48147-C6-6R (AEI/菲德、欧盟)。SV 承认欧洲联盟和南亚区域联合ﬁnanced SoMoPro 第二方案的支持, 通过赠款4SGA8678。jč承认 MEYS 提供的资金, 项目 No。LQ1601 (CEITEC 2020)。这项研究的一部分利用了六研究中心的基础设施, 通过捷克共和国教育、青年和体育部资助的 CEITEC 开放项目下的 CEITEC 的核心设备, 以及西班牙信通技术网络 MICRONANOFABS 部分支持的 MINECO。

备注: 出于安全原因, 反应单元和气溶胶发生器放置在通风罩内。使用镊子来处理样品, 戴手套, 实验室大衣和护目镜, 并遵循常见的实验室安全做法. 
 1。衬底的制备及沉积温度的设置 <ol> <li> 使用菱形笔尖剪切器切割 10 mm x 10 mm 的硅基板 (基板尺寸已适应我们的反应单元大小)。在本试验中, 使用自制的不锈钢圆柱反应单元, 其内部容积为 7000 mm 3 (直径:30 mm, 高度:10 mm), 适应于用于制造的硅微机械平台的尺寸的气体传感器. </li>
	<li> 用异丙醇清洗基体, 用去离子水冲洗, 用氮气吹干基体, 确保薄膜的附着力和基体的均匀覆盖. </li>
	<li> 将衬底放入反应单元。当使用硅基微机械平台, 而不是裸硅衬底制造气体传感器, 把微机械平台的反应细胞, 然后与阴影的面具, 以限制增长的材料的面积兴趣. </li>
	<li> 关闭反应单元。确保反应单元的盖子正确密封, 以避免活性物质的泄漏. </li>
	<li> 合闸温度控制系统, 包括与反应电池集成的电阻加热器、热电偶, 以感知基板的温度和比例积分导数 (PID) 控制器. </li>
	<li> 将温度设置为400和 #176; C 让它稳定 (这个过程大约需要30分钟, 但它可能会根据反应细胞的尺寸和温度控制系统的特性而变化). </li>
</ol> 2。气溶胶生成溶液的制备 <ol> <li> 添加50毫克的 ZnCl 2 到100毫升的玻璃瓶装有真空阱 (29/32 接头, 200 毫米长度, 5 毫米软管倒钩). </li>
	<li> 溶解 ZnCl 2 在5毫升乙醇中, 然后用真空阱将瓶子盖住。确保下管端坐60毫米以上的瓶子底部, 并没有淹没在解决方案。如果需要, 使用玻璃接头夹在 CVD 过程中将瓶子和真空阱固定在一起. </li>
	<li> 将小瓶夹紧到通用支架上。调整的高度, 以满足瓶底和超声雾化器的最佳焦点, 在1.6 兆赫运作, 并提供了平均大小的气溶胶雾滴和 #8764; 3 和 #181; m. </li>
	<li> 分别将真空阱的入口和排气连接到氮气管道和反应单元, 如 "气溶胶辅助 CVD 系统的简化方案" 中所示 图 1 . </li>
	<li> 对每种沉积物使用新的反应液. </li>
</ol> 3。cvd 过程 <ol> <li> 在启动 cvd 过程之前, 请验证反应单元中的温度是否已达到稳定状态. </li>
	<li> 将氮气流量调整到 200 cm 3 /分钟, 并允许它流经系统 (根据我们的实验中所用的反应单元的尺寸, 流量已经调节)。建议使用质量流量控制器, 以确保在沉积过程中恒定流动. </li>
	<li> 合闸气溶胶发生器, 并保持气溶胶常数在这个过程中, 直到包含锌前驱体的溶液完全交付到反应细胞 (这个过程需要大约120分钟, 考虑5毫升的溶液体积和流速200厘米 3 /分钟. </li>
	<li> 当解决方案已完全交付给反应单元, 断的气溶胶发生器和温度系统冷却反应细胞。同时保持氮气在整个系统中流动. </li>
	<li> 当温度降至室温时, 关闭氮气流, 打开反应单元, 并取出样品。基板将显示在表面上的灰哑光颜色, 不同于闪亮的裸硅片 (硅微机械平台在 CVD 步骤后显示类似的外观)。这种无光泽的颜色与柱状 ZnO 结构的存在有关, 如扫描电子显微镜观察到的那样 ( 图 2 ). </li>
</ol>

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作者没有透露

这里详述的气雾剂辅助 CVD 过程在10毫米 x 10 毫米的硅瓦片导致 ZnO 棒的形成。这个做法可以被扩大到外套更大的表面;然而, 注意到反应细胞体积的增加将需要调整参数, 如载流子流速和溶液体积。对于较大的反应电池, 也建议控制在基板的温度梯度, 由于微妙的梯度小于10° c 可能有强烈的影响, 由此产生的形态学的胶片, 如前所示氧化钨的气溶胶辅助 CVD8。为了重现在这里报告的结果, 我们建议使用与协议中描述的类似的工作频率的超声波雾化器, 因为气溶胶的平均雾滴大小和由此产生的薄膜形貌受到此参数7。
其他 ZnO 形貌的选择性沉积, 而不是棒, 也可以通过改变前驱体、沉积温度或载体溶剂来实现。例如, 使用前体, 如二乙锌14或醋酸锌的15 , 已被证明导致形成其他形态的形式, 而不是六角棒。我们还注意到, 在气溶胶辅助 CVD 过程中使用不同的沉积温度会产生薄膜的形貌变化, 从而在400° c 以下温度下形成多晶薄膜, 在当达到600° c 时, 基体上的温度超过400° c, 或退化且密度较低的结构。同样, 使用不同的溶剂会影响薄膜的形貌, 例如, 我们最近已经证明, 在400° c 的沉积温度下使用甲醇鼓励形成具有鳞片状形貌的结构, 而丙酮在相同温度下的使用鼓励了倒锥状结构的形成9。
温度和载体溶剂的作用以前也被注意了在其他金属氧化物结构的气雾剂辅助的 CVD (例如, 氧化钨的5和氧化锡6), 并且它一般归因于: 化学作用由反应性中间体引起, 在处理温度下成为活跃种类为沉积或反应均匀地形成固体微粒 (这更可能为溶剂例如甲醇和丙酮, 在低温可能分解如, #60; 500 ° c);和调制率的沉积 (通量) 和雾滴蒸发 (这是更有可能占主导地位的溶剂作为乙醇, 不形成活性的自由基物种的温度在我们的实验中使用)。
此处报告的协议与基于硅的电子器件的最先进的微细加工工艺相兼容, 并有可能在涉及高耐热柔性材料的过程中被纳入, 因为相对较低结构的气溶胶辅助 CVD 的温度。然而, 重要的是要提到, 使用阴影面具的选择增长的结构, 如在种子方法的基础上的蒸气-液体-固体机制16, 可能有限制在某些制造过程。另一方面, 通过这里提出的催化的方法来发展结构的可能性可能具有较少的光刻和金属化步骤的优势, 在芯片集成的结构。此外, 相对低温的合成 ZnO 棒也可能允许使用这种方法与局部加热, 一种技术, 用于限制所需的热环境分解的气相反应物和结构的生长动力学对一个微型区域, 极大地减少功率消耗量高温 (热壁) 反应器17。例如, 在催化气溶胶辅助的氧化钨燃料的 CVD 中, 使用局部加热已经证明是可行的18。在化学传感、光催化、光子学和能量等领域, 具有受控形态的柱状 ZnO 结构的生长, 使其易于集成到不同的基体和微细加工过程中, 具有共同的兴趣。收割, 除其他之外。

ZnO 是一种具有宽直带隙 (3.37 eV)、大激子结合能 (60 兆伏特)、自发极化和压电常数的 II-VI 半导体, 使其成为电子、光电子、能量发生器的极具吸引力的材料,光催化和化学传感。ZnO 的大部分有趣的功能与它的矿晶体结构及其非极性 (例如、{100}、{110}) 和极 (例如、{001}、{111}) 曲面相关, 与特定的结构化形态表 (例如:, 棒, 金字塔, 盘子)。这些形态形式的控制需要合成方法, 能够产生定义明确的晶体, 具有均匀的尺寸、形状和表面结构1,2,3,4。在这种情况下, 新的添加剂 (自下而上的合成) 制造策略, 特别是基于气相路线是工业上有吸引力的和潜在的优势, 因为它们提供的能力, 产生结构化的电影在连续而比具有高纯度和高吞吐量的间歇模式。这些路线以前显示了 ZnO 结构的影片的形成, 但通常使用催化剂种子例如金子并且/或者高处理温度 900-1300 ° c2 {Wang, 2008 #491} (这可能是不方便的某些制造过程由于需要额外的处理步骤和/或温度不兼容的芯片集成)。
最近, 我们使用了气相法, 基于气溶胶辅助 CVD 的无机或金属-有机前体, 以实现选择性沉积金属氧化物结构 (例如, 氧化钨的5或锡氧化物6), 没有需要的催化剂种子和在较低的温度比那些报告的传统 CVD。这种方法在大气压下工作, 可以使用比传统 CVD 更少的挥发性前体;溶解性是关键的前驱体要求, 因为前驱体溶液以气溶胶形式传递到反应区7。在气溶胶辅助 CVD 中, 结构材料和薄膜的成核和生长动力学受反应物种的合成温度和浓度的影响, 从而影响膜的形态形式的8。最近, 我们研究了 zno 对各种气溶胶辅助 CVD 条件 (包括前体、温度、载体溶剂和前驱体浓度) 的形貌依赖性, 并找到了结构化 zno 与棒的形成途径,片状或倒锥体状的形态, 在其他9中。
在本文中, 我们提出了由 {100} 表面组成的棒状 ZnO 结构的气溶胶辅助 CVD 的协议。该协议与各种衬底兼容, 包括硅, 硅基微机械平台, 石英, 或高耐热聚酰亚胺箔。在这份报告中, 我们专注于裸硅片的涂层和用于制造气体传感器的基于硅的微机械平台。氧化锌气溶胶辅助 CVD 由三处理步骤组成, 包括: 制备基底和沉积温度的设置、气溶胶生成溶液的制备和 cvd 过程。下面详细介绍了这些步骤, 并在图 1中显示了显示系统主要元素的示意图视图.

<table><tbody><tr><td>ZnCl&lt;sub&gt;2&lt;/sub&gt; 99,999 % trace metal basis</td><td>Sigma-Aldrich&amp;nbsp;</td><td>229997</td><td>used as purchased from manufacturer</td></tr><tr><td>Ethanol &amp;ge;96%</td><td>Penta</td><td>71430</td><td>used as purchased from manufacturer</td></tr><tr><td>Reaction cell&amp;nbsp;</td><td>home-made</td><td></td><td>stainless steel cylindrical reaction cell (7000 mm&lt;sup&gt;3&lt;/sup&gt;, diameter: 30 mm, height: 10 mm) with integrated heaters to reach the temperature of deposition and provided with a PID controller</td></tr><tr><td>Ultrasonic liquid atomizer</td><td>Johnson Matthey</td><td></td><td>Operating frequency &amp;sim;1,6 MHz</td></tr><tr><td>Flowmeter</td><td></td><td></td><td>To have a better control of this step the use of a mass flow controller is recommended.&amp;nbsp;</td></tr><tr><td>Nitrogen</td><td>Linde Gas A.S.</td><td></td><td></td></tr><tr><td>Silicon wafers&amp;nbsp;&amp;nbsp;</td><td>MicroChemicals</td><td></td><td>&amp;lt;100&gt;, p-type, 525 &amp;micro;m thick, cut into pieces (10 mm &amp;times; 10 mm )</td></tr><tr><td>Glass vial - 100 ml</td><td></td><td></td><td>29/32 joint, 200 mm lenght</td></tr><tr><td>Vacuum trap</td><td></td><td></td><td>29/32 joint, 5 mm hose barbs&amp;nbsp;</td></tr><tr><td>Graduated cylinder - 10 ml</td><td></td><td></td><td></td></tr><tr><td>Universal support&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Balance</td><td></td><td></td><td></td></tr><tr><td>Scanning Electron Microscopy (SEM)</td><td>Tescan</td><td>Mira II LMU</td><td></td></tr><tr><td>X-ray diffraction (XRD)</td><td>Rigaku&amp;nbsp;</td><td>Smart Lab 3kW</td><td>Cu K&amp;alpha; radiation</td></tr><tr><td>X-ray Photoelectron spectroscopy (XPS)</td><td>Kratos</td><td>AXIS Supra</td><td>Monochromatic&amp;nbsp; K&amp;alpha; radiatio, 300 W emission power, magnetic lens, and charge compensation&amp;nbsp;</td></tr><tr><td>Transmission Electron Microscopy (TEM)</td><td>Jeol</td><td>JEM 2100F</td><td>operated at 200kV using Schottky cathode and equiped with EDX&amp;nbsp;</td></tr></tbody></table>

aerosol-assisted chemical vapor deposition of metal oxide structures: zinc oxide rods

虽然柱状氧化锌 (ZnO) 结构以棒或线的形式在以前被不同的液体或气相路线合成, 它们的高成本生产和/或与微细加工技术的不相容, 由于使用pre-deposited 催化剂-种子和/或高处理温度超过900° c, 代表了普遍使用这些方法的一个缺点。然而, 在这里, 我们报告的合成氧化锌棒通过一个催化蒸气固体机制启用了使用气溶胶辅助化学气相沉积 (CVD) 方法在400° c 与氯化锌 (ZnCl2) 作为前体和乙醇作为载体溶剂。这种方法提供了 ZnO 棒的单步形成和与各种基材类型直接集成的可能性, 包括硅、硅微机械平台、石英或高耐热聚合物。这可能有助于在 large-scale 中使用此方法, 因为它与设备制造的最先进的微细加工工艺相兼容。本报告还描述了这些结构的性质 (例如、形态学、晶相、光带间隙、化学成分、电阻) 并验证其对一氧化碳的气体传感功能。

在乙醇中溶解的 ZnCl2的气溶胶辅助 CVD 导致在裸硅片上形成灰均匀的和附着的薄膜 (机械上相对容易磨损)。利用扫描电子显微镜 (SEM) 对薄膜进行表征, 8,000X 放大显示 quasi-aligned 六角形 ZnO 棒, 长度为∼1,600 和∼380 nm 直径 (图 2)。在设定点温度下的较大误差或在 CVD 过程中沿基底温度梯度的存在可能导致其他 ZnO 形貌的沉积 ,如 (图3) 或具有非均匀结构的薄膜。此外, 不均匀或换药的涂层可能部分地与温度控制差、流量的不正确调整和/或使用不同的载体溶剂, 而不是本议定书所规定的。
x 射线衍射 (XRD) 分析的棒显示与六角氧化锌相关联的衍射模式 (P63mc空间组, a = 3.2490 Å, b = 3.2490 Å, 和c = 5.2050 Å;iccd/cop No. 5-0664)。这些模式在 34.34°2θ上显示一个高强度的衍射峰值, 对应于六角氧化锌相的 (002) 平面, 与其他七低强度衍射峰在 31.75, 36.25, 47.54, 56.55, 62.87, 67.92, 和 72,61° 2θ, 对应于六角氧化锌相的 (100) (101) (102) (110) (103) (201) 和 (004) 平面。通过高分辨率透射电子显微镜 (TEM) 表征棒材, 显示出标出的平面间距 (0.26 nm) 与 x 射线衍射识别的 (002) 平面 (d = 0.26025 nm) 的内部晶格相一致。能量色散 X 射线 (EDX) 光谱学显示了锌的存在相对地低氯污秽 (发现为氯: 锌0.05 在%)。
通过薄膜的漫反射测量来估计杆的光带隙, 表示 3.2 eV 的光带隙, 与 ZnO10的文献值一致。用 X 射线光电子能谱 (XPS) 分析薄膜的特点是锌 2p1/2和 zn 2p3/2核心级峰值光谱分别为1045和 1022 eV, 一致与那些早先被观察的那些为 ZnO11,12。
该协议的使用, 在基于硅的微机械平台的气体传感, 导致直接集成的柱状 ZnO 棒限制在传感活动区 (400 x 400 µm2), 这是由阴影掩码定义。该薄膜的电阻ω (∼100ω) 在室温下, 使用指电极集成到硅微机械平台中进行测量。图4显示基于气溶胶辅助 CVD 棒的四微机械气体传感器阵列的图片。本文介绍了微机械平台的特点和制作过程, 并描述了13。这些微计算机系统是敏感的相对低浓度的一氧化碳, 最大的反应记录 (使用连续气体流量测试室13) 时, 传感器的操作在360° c 使用电阻 microheaters 集成在系统中 (图 5)。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56127/56127fig1.jpg"> 
图1:气溶胶辅助 CVD 系统的示意图.
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56127/56127fig2.jpg"> 
图2:顶部 (A) 和横截面 (B) 通过气溶胶辅助 CVD 沉积的 ZnO 棒的 SEM 图像。<a href="//ecsource.jove.com/files/ftp_upload/56127/56127fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56127/56127fig3.jpg"> 
图3:ZnO 在 300 (A)、400 (B)、500 (C) 和600° c (D) 上沉积的via气雾剂辅助 CVD 的横断面 SEM 图像。<a href="//ecsource.jove.com/files/ftp_upload/56127/56127fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56127/56127fig4.jpg"> 
图4:硅基微机械平台, 4 传感器安装在 TO8-package (a) 上, 并详细查看传感器 (B) 和沉积在电极边缘 (C) 的 ZnO 棒。<a href="//ecsource.jove.com/files/ftp_upload/56127/56127fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/56127/56127fig5.jpg"> 
图5:氧化锌棒对不同浓度 (25、20、10和 5 ppm) 的电阻变化.<a href="//ecsource.jove.com/files/ftp_upload/56127/56127fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods at JoVE.com

Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

金属氧化物结构的气溶胶辅助化学气相沉积: 氧化锌棒

在不使用 pre-deposited 催化剂-种子颗粒的情况下, 通过气溶胶辅助化学气相沉积法合成柱状氧化锌结构。这种方法是可伸缩和兼容的各种基板的基础上, 无论是硅, 石英或聚合物。

Whilst columnar zinc oxide (ZnO) structures in the form of rods or wires have been synthesized previously by different liquid- or vapor-phase routes, ...

aerosol-assisted-chemical-vapor-deposition-metal-oxide-structures

Research

JoVE Journal

Chemistry

13.1K 次观看.  Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC). 在不使用 pre-deposited 催化剂-种子颗粒的情况下, 通过气溶胶辅助化学气相沉积法合成柱状氧化锌结构。这种方法是可伸缩和兼容的各种基板的基础上, 无论是硅, 石英或聚合物。

视频: Aerosol-assisted Chemical Vapor Deposition of Metal Oxide Structures: Zinc Oxide Rods

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.

通过电荷分离纳米晶及其固体收获太阳能

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

科研

工程学

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

制备纳米设计的脉冲激光沉积透明导电氧化物

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and reduction half reactions, and fast electron (hole) diffusion and charge separation. Nanowires present suitable architectures to meet these requirements. Axially segmented Ag|ZnO and radially segmented (coaxial) TiO2-Ag nanowires with a diameter of 200 nm and a length of 6-20 &#181;m were made by templated electrodeposition within the pores of polycarbonate track-etched (PCTE) or anodized aluminum oxide (AAO) membranes, respectively. In the photocatalytic experiments, the ZnO and TiO2 phases acted as photoanodes, and Ag as cathode. No external circuit is needed to connect both electrodes, which is a key advantage over conventional photo-electrochemical cells. For making segmented Ag|ZnO nanowires, the Ag salt electrolyte was replaced after formation of the Ag segment to form a ZnO segment attached to the Ag segment. For making coaxial TiO2-Ag nanowires, a TiO2 gel was first formed by the electrochemically induced sol-gel method. Drying and thermal annealing of the as-formed TiO2 gel resulted in the formation of crystalline TiO2 nanotubes. A subsequent Ag electrodeposition step inside the TiO2 nanotubes resulted in formation of coaxial TiO2-Ag nanowires. Due to the combination of an n-type semiconductor (ZnO or TiO2) and a metal (Ag) within the same nanowire, a Schottky barrier was created at the interface between the phases. To demonstrate the photocatalytic activity of these nanowires, the Ag|ZnO nanowires were used in a photocatalytic experiment in which H2 gas was detected upon UV illumination of the nanowires dispersed in a methanol/water mixture. After 17 min&#160;of illumination, approximately 0.2 vol% H2 gas was detected from a suspension of ~0.1 g of Ag|ZnO nanowires in a 50 ml 80 vol% aqueous methanol solution.

Preparation and Use of Photocatalytically Active Segmented Ag|ZnO and Coaxial TiO2-Ag Nanowires Made by Templated Electrodeposition

Procedures are outlined to prepare segmented and coaxial nanowires via templated electrodeposition in nanopores. As examples, segmented nanowires consisting of Ag and ZnO segments, and coaxial nanowires consisting of a TiO2 shell and a Ag core were made. The nanowires were used in photocatalytic hydrogen formation experiments.

制备和使用光催化活性分段银|氧化锌和二氧化钛同轴<sub&gt; 2</sub&gt;银纳米线制成由模板电

Photocatalytically active nanostructures require a large specific surface area with the presence of many catalytically active sites for the oxidation and ...

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices.

Tin sulfide (SnS) is a candidate material for Earth-abundant, non-toxic solar cells. Here, we demonstrate the fabrication procedure of the SnS solar cells employing atomic layer deposition, which yields 4.36% certified power conversion efficiency, and thermal evaporation which yields 3.88%.

通过热蒸发和原子层沉积使记录效率的SnS太阳能电池

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent ...

Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO

Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu2O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu2O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu2O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu2O interface. Optimization of AP-SALD conditions as well as keeping Cu2O away from air and moisture in order to minimize Cu2O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn1-xMgxO/Cu2O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu2O-based photovoltaics.

Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO

Here we present a protocol for synthesizing Zn1-xMgxO/Cu2O heterojunctions in open-air at low temperature via atmospheric pressure spatial atomic layer deposition (AP-SALD) of Zn1-xMgxO on cuprous oxide. Such high quality conformal metal oxides can be grown on a variety of substrates including plastics by this cheap and scalable method.

在铜改善异质结质量<sub&gt; 2</sub&gt; O型的太阳能电池通过大气压力的空间原子层沉积的优化<br /&gt;锌<sub&gt; 1-X</sub&gt;镁<sub系列&gt; X</sub&gt; 0

Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O ...

化学

Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance.
For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application.

We offered a method to directly synthesize high c-axis (0002) ZnO thin film by plasma enhanced chemical vapor deposition. The as-synthesized ZnO thin film combined with Pt interdigitated electrode was used as sensing layer for ultraviolet photodetector, showing a high performance through a combination of its good responsivity and reliability.

合成和高c轴ZnO薄膜等离子体的特性增强化学气相沉积系统及其紫外探测器的应用

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto ...

Seedless Growth of Bismuth Nanowire Array via Vacuum Thermal Evaporation

Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. Conventionally reserved for the fabrication of metal thin films, thermal evaporation deposits bismuth into an array of vertical single crystalline nanowires over a flat thin film of vanadium held at RT, which is freshly deposited by magnetron sputtering or thermal evaporation. By controlling the temperature of the growth substrate the length and width of the nanowires can be tuned over a wide range. Responsible for this novel technique is a previously unknown nanowire growth mechanism that roots in the mild porosity of the vanadium thin film. Infiltrated into the vanadium pores, the bismuth domains (~ 1 nm) carry excessive surface energy that suppresses their melting point and continuously expels them out of the vanadium matrix to form nanowires. This discovery demonstrates the feasibility of scalable vapor phase synthesis of high purity nanomaterials without using any catalysts.

A protocol for seedless and high yield growth of bismuth nanowire arrays through vacuum thermal evaporation technique is presented.

铋纳米线阵列通过真空热蒸发无核增长

Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. ...

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.

利用预热水热氧化锌纳米棒/石墨烯/氧化锌纳米棒外延双异质结的机压电纳米发电机的研制

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%.

定向定向 ZnO 纳米阵列及其在倒小分子太阳电池中的应用

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

Zinc-Sponge Battery Electrodes that Suppress Dendrites

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are characterized by creating a paste made of zinc particles, organic porogen, and viscosity-enhancing agent that is heated under an inert gas and then air. During heating under the inert gas, the zinc particles anneal together, and the porogen decomposes; under air, the zinc fuses and residual organic burns out, yielding an open-cell metal foam or sponge. We tune the mechanical and electrochemical properties of the zinc sponges by varying zinc-to-porogen mass ratio, heating time under inert gas and air, and size and shape of the zinc and porogen particles. An advantage of the reported methods is their ability to finely tune zinc-sponge architecture. The selected size and shape of the zinc and porogen particles influence the morphology of the pore structure. A limitation is that resulting sponges have disordered pore structures that result in low mechanical strength at low volume fractions of zinc (&#60;30%). Applications for these zinc-sponge electrodes include batteries for grid-storage, personal electronics, electric vehicles, and electric aviation. Users can expect zinc-sponge electrodes to cycle up to 40% depth of discharge at technologically relevant rates and areal capacities without the formation of separator-piercing dendrites.

The goal of the reported protocols is to create rechargeable zinc-sponge electrodes that suppress dendrites and shape change in zinc batteries, such as nickel&#8211;zinc or zinc&#8211;air.

抑制登德里特的锌海绵电池电极

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are ...