这个研究项目是由澳大利亚研究理事会通过联动授予南玻太阳能Pty有限公司荆绕支持，承认她的大学，新南威尔士州副校长博士后奖学金。 SEM图像采取通过Jongsung公园使用由新南威尔士大学的电子显微镜单位提供的设备。

1。多晶硅太阳能电池的制作（动画3） <ol><li>硅薄膜沉积<ol class="lalpha"><li>电子束蒸发工具准备烘烤出来〜100°C过夜，以达到&lt;3E-8托基地的压力。预置样本加热到150℃待机温度。 </li><li>使用5x5厘米2（或10×10厘米2）基板硼硅玻璃（肖特Borofloat33），1.1或3.3毫米厚，涂〜80纳米的氮化硅（由PECVD准备从N 2和SiH 4的混合物）制成的基板。 </li><li>基材表面干燥氮气吹，以去除灰尘，并放置到样品架。发泄锁的负载，加载样本，泵负载锁定压力&lt;1E5托，样品传送到主室。启动加热到250°C的设定点约20分钟的泵，当压力达到8E-8 Torr或更低。 </li><li>检查的掺杂源和硅源百叶窗关闭。预置的掺杂源温度为待机温度，即磷源温度在700°C和硼离子源温度在1250°C。启动电子枪，电子枪电流缓慢增加，熔体硅坩埚。 </li><li>时所需的电流达到（从以前的校准:这个电流的电子枪和硅源条件的不同而不同），蒸发所需浓度的P和B掺杂的硅层:35在1E20厘米纳米发射-3的P 2〜3在5E15厘米-3 B的微米吸收100 nm的背表面场（BSF），在4E19厘米-3 B.精确的掺杂浓度达到某些硅沉积速率匹配，测量石英晶体显示器天平（QCM），具有一定的掺杂源的温度，使用SIMS的校准建立了合作关系。 </li><li>蒸发后进行切换关闭加热器，降温〜10分钟的样品。反FER样品负载锁，关闭闸门阀，泄负载锁和卸载的硅薄膜样品。 </li></ol></li><li>硅结晶 如果样品是10×10厘米2，它可以被切割成四个5x5厘米2细胞块大小之前结晶。放置一个粗糙和氮化硅涂层，肖特Robax玻璃（避免粘）持有人（Si薄膜）玻璃上沉积硅薄膜。负载成氮清除烤箱预热至200-300°C。提高温度高达600°C时，3〜5°C /分钟和30小时退火。打开烤箱加热，让烘箱降温自然〜200℃（2〜3小时）起卸前的样品。样品可以有一个凹的形状，由于硅结晶过程中的收缩。这将在下面的快速热加工扁平化。 </li><li>掺杂活化和缺陷退火（RTA） 将样品持有人的结晶膜制成的石墨和LOAD以快速热处理器氩清除。坡道的温度高达600°C时，1°C / S，则高达1000°C在20°C /秒，保持1分钟，然后冷却下来自然〜100°C和卸载。 </li><li>去除表面氧化 立即前到氢化硅薄膜表面氧化过程中形成的结晶和RTA必须拆除，以确保裸露的硅薄膜表面接触到氢。直到硅片表面变为疏水退火样品浸入5％HF溶液（30〜100秒）。与去离子水冲洗和干燥氮气枪。 </li><li>缺陷钝化 样品装入真空室配备了远程氢等离子体源。抽空&lt;1E-4托，加热样品〜620°，打开氩气/氢气的混合物流量（50:150 SCCM），设置压力50-100毫托，开始在3.5千瓦的等离子源微波功率和继续〜10分钟的过程。关闭加热器电源，而mainta伊宁10-15分钟的血浆，直到温度低于350℃之前，血浆和停止气体流量。卸载样品，当温度低于200°C </li><li>细胞金属化 细胞金属化进行了一系列连续的光刻图案，铝薄膜沉积与蚀刻步骤，详细描述在11。最终细胞看起来像在最后一张幻灯片的动画3所示。金属化细胞的特写视图如图1所示。 </li><li>测量EQE的金属化细胞。 </li></ol> 2。制作电浆银纳米粒子（动画4） <ol><li>用干燥的氮气吹金属化的细胞表面，去除灰尘和热蒸发器包含一个W的船装满银颗粒（0.3-0.5克）装入样品。抽空蒸发器室基地的压力2〜3E-5托。方案的QCM对Ag参数:密度10.50Z比0.529。 </li><li>确保样品快门关闭，关闭的W船加热器和增加电流，足够慢，以避免以上8E-5 Torr的压力上升，直到银颗粒融化（如通过观察视图端口）。压力稳定后的电流设定点对应的A / S（校准）0.1-0.2银沉积速率，并打开快门开始沉积过程。 </li><li>监测使用的QCM增长的Ag膜厚度和关闭快门时达到14纳米的厚度。允许在W船约15分钟冷却下来，卸载样品。电影应退火形成纳米颗粒沉积后尽快，尽可能地避免银氧化。 </li><li>新鲜沉积的Ag膜的细胞被置于氮气清除烤箱预热到230 0.1-0.2℃，退火50分钟，然后卸载。注意:由于纳米粒子的表面外观的变化。银纳米粒子的扫描电子显微镜图像是SHOWN 图。 2。 </li><li>测量EQE的细胞与纳米粒子阵列。 </li></ol> 3。制作后反射后方的反射〜300 nm厚的氟化镁（1.38注册机）介质熔覆与商业白色的天花板漆（多乐士）的外衣。 <ol><li>编造后反射之前，必须用黑色记号笔墨水保护细胞接触，这使得从下介质由升空过程中暴露的接触。 </li><li>使用氮气枪吹NP阵列和画接触，清除灰尘的样品。使用温和的氮气压力和运动保健不吹纳米粒子。放入热蒸发器包含一个W船充满氟化镁2件样品。蒸发器泵2〜3E-5 Torr的压力。 氟化镁的QCM参数为:密度3.05和Z比0.637。 </li><li>确保样品shutter被关闭，打开船加热器，慢慢加大电流，以避免过多的压力上升，直到氟化镁熔体通过视图端口。压力稳定后的电流设定点，对应的氟化镁的沉积速率为0.3 nm / s的和打开样品快门。 </li><li>监测使用的QCM沉积厚度和关闭快门时达到300海里。 </li><li>关闭加热器。允许的W船约15分钟冷却下来，卸载样品。注意:在氟化镁2熔覆细胞形态的变化。 </li><li>要取出的细胞接触的油墨面膜浸入丙酮熔覆与介质的细胞。等到开始开裂，抬起上面的油墨介质。保持在丙酮中的细胞，直到所有的墨水与介质和金属接触，充分暴露。从丙酮中取出样品，新鲜的丙酮冲洗和干燥氮气枪。 </li><li>应用层罚款对整个细胞表面的软刷白色油漆（多乐士单涂层的天花板油漆）小心地避免金属接触。油漆层有足够厚，是完全不透明（〜&gt;0.5毫米），所以没有光可以看到在明亮的光源，通过描绘细胞时。让漆干一天。 </li><li>用白色油漆后反射测量细胞EQE。 </li></ol> 4。代表结果通过整合全球标准太阳光谱的EQE曲线（气团1.5）太阳能电池的短路电流计算。无论是电池的电流，其增强由于光捕获依赖于细胞吸收层厚度:目前本身是较高较厚的细胞，但更薄的设备，看到EQE各自的数据和动画5，表1是当前加强高曲线。原来的2微米厚的细胞，没有光捕获，HAVE JSC测量步骤1.7。〜15毫安/厘米2）。后的纳米粒子阵列的制造，的JSC增加了约20毫安/平方厘米 ，其中32％提高。它是略高于由后方的漫反射，只有25-30％的提升效果更好。后加入氟化镁后熔覆细胞与电浆纳米阵列的漫反射，进一步提高司法人员叙用委员会 22.3毫安/厘米2，或45％左右提高。请注意，所有电流为3微米厚的细胞较高，而相对提高到25.7毫安/厘米2略低，42％的光捕获在更薄的设备有较大的影响。 <table border="1"><tbody><tr><td> 电池厚度: </td><td colspan="2"> 2微米 </td><td colspan="2"> 3微米 </td></tr><tr><td></td><td> JSC，毫安/厘米2 </td><td><s<html>阮富仲&gt;％以上</td><td> JSC，毫安/厘米2 </td><td> ％以上 </td></tr><tr><td>原始细胞</td><td> 15.4 </td><td></td><td> 18.1 </td><td></td></tr><tr><td>后漫反射（R）的</td><td> 20.1 </td><td> 30.5 </td><td> 21.5 </td><td> 18.8 </td></tr><tr><td>纳米粒子（NP方案） </td><td> 20.3 </td><td> 31.8 </td><td> 21.9 </td><td> 21.0 </td></tr><tr><td> NP /氟化镁2 / </td><td> 22.3 </td><td> 45.3 </td><td> 25.7 </td><td> 42.0 </td></tr></tbody></table> 表1。电浆电池短路电流和原始细胞相比，其增强。 <img alt="图1" src="/files/ftp_upload/4092/4092fig1.jpg" /> 图1。特写多晶硅薄膜太阳能电池与金属化网格细胞。 / ftp_upload/4092/4092fig2.jpg"/&gt; 图2银纳米粒子的电子显微镜图像扫描的硅表面上。 <img alt="图3" src="/files/ftp_upload/4092/4092fig3.jpg" /> 图3。1电浆薄膜晶体硅太阳能电池（不按比例）的示意图。 <img alt="图4" src="/files/ftp_upload/4092/4092fig4.jpg" /> 图4外部量子效率和短路电流的多晶硅薄膜与漫反射和电浆纳米细胞:虚线黑-原来的2微米厚的细胞，没有光捕获，JSC15.36毫安/厘米2;蓝色-细胞。弥漫油漆反射，JSC 20.08毫安/厘米2;红-与电浆银纳米粒子的细胞，JSC20.31毫安/厘米2;绿色-细胞的纳米粒子， 氟化镁，和弥漫性涂料的反射，JSC </eM&gt;22.32毫安/厘米2。紫色- 3微米厚的细胞（3毫米厚的玻璃），纳米粒子， 氟化镁，和漫反射，JSC 25.7毫安/厘米2（注意蓝色低因无意在AR层和发射层厚度差异）。坚实的黑色- 2微米厚的等离子体增强化学气相沉积法（3毫米厚的玻璃），JSC26.4毫安/厘米2，比较所示的纹理单元准备。 动画1。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4092/4092animation1.pptx" target="_blank">点击这里查看动画</a> 。 动画2。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4092/4092animation2.pptx" target="_blank">点击这里查看动画</a> 。 动画3。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4092/4092animation3.pptx" target="_blank">点击这里查看动画</a>。 动画4。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4092/4092animation4.pptx" target="_blank">点击这里查看动画</a> 。 动画5。 <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/4092/4092animation5.pptx" target="_blank">点击这里查看动画</a> 。

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	<li>Henley, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kerf-free+wafering.">Kerf-free wafering.</a> , 1184-1192 (2010).</li><li>Kunz, O., Wong, J., Janssens, J., Bauer, J., Breitenstein, O., Aberle, A. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shunting+problems+due+to+sub-micron+pinholes+in+evaporated+solid-phase+crystallised+poly-Si+thin-film+solar+cells+on+glass.">Shunting problems due to sub-micron pinholes in evaporated solid-phase crystallised poly-Si thin-film solar cells on glass.</a> Progress Photovoilt.: Res. Appl. 17, 35-46 (2009).</li><li>Kunz, O., Ouyang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5%+Efficient+evaporated+solid-phase+crystallised+polycrystalline+silicon+solar+cells.">5% Efficient evaporated solid-phase crystallised polycrystalline silicon solar cells.</a> Progress Photovolt.: Res. Appl. 17, 567-573 (2009).</li><li>Van Nieuwenhuysen, K., Payo, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epitaxially+grown+emitters+for+thin+film+silicon+solar+cells+result+in+16%+efficiency.">Epitaxially grown emitters for thin film silicon solar cells result in 16% efficiency.</a> Thin Solid Films. 518, S80-S82 (2008).</li><li>Lee, B. G., Stradin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-trapping+by+a+dielectric+nanoparticle+back+reflector+in+film+silicon+solar+cells.">Light-trapping by a dielectric nanoparticle back reflector in film silicon solar cells.</a> Appl. Phys. Lett. 99, 064101 (2011).</li><li>Catchpole, K. R., Polman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasmonic+solar+cells.">Plasmonic solar cells.</a> Optics Express. 16, 21793-21800 (2008).</li><li>Ouyang, Z., Zhao, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+enhanced+light-trapping+in+thin-film+silicon+solar+cells.">Nanoparticle enhanced light-trapping in thin-film silicon solar cells.</a> Progress Photovolt.: Res. Appl. 19, 917-926 (2011).</li><li>Catchpole, K. R., Polman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+principle+for+particle+plasmon+enhanced+solar+cells.">Design principle for particle plasmon enhanced solar cells.</a> Appl. Phys. Lett. 93, 191113 (2008).</li><li>Beck, F. J., Mokkapati, S., Polman, A., Catchpole, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Asymmetry+in+photocurrent+enhancement+by+plasmonic+nanoparticle+arrays+located+on+the+front+or+on+the+rear+of+solar+cells.">Asymmetry in photocurrent enhancement by plasmonic nanoparticle arrays located on the front or on the rear of solar cells.</a> Appl. Phys. Lett. 96, 033113 (2008).</li><li>Beck, F. J., Verhagen, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resonant+SPP+modes+supported+bt+discrete+metal+nanoparticles+on+high+index+substrates.">Resonant SPP modes supported bt discrete metal nanoparticles on high index substrates.</a> Optics Express. 19, 146-156 (2010).</li><li>Kunz, O., Ouyang, Z., al, a. t. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=5%+Efficient+evaporated+solid-phase+crystallised+polycrystalline+silicon+thin-film+solar+cells.">5% Efficient evaporated solid-phase crystallised polycrystalline silicon thin-film solar cells.</a> Progress Photovolt. 17, 567-573 (2009).</li><li>Keevers, M. J., Young, T. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=10%+Efficient+CSG+minimodules.">10% Efficient CSG minimodules.</a> , 1783-1790 (2007).</li></ol>

没有利益冲突的声明。

蒸发多晶硅太阳能电池及电浆纳米粒子光散射的光捕获的理想合作伙伴。这种细胞是平面的，因此，他们不能依靠光散射表面纹理，也可以很容易地在粗糙的表面形成电浆纳米。细胞有直接接触的硅，这也恰好是最好的最有效的电浆光散射纳米粒子的位置只有一个，后表面。此外，纳米热退火形成的最简单的方法也是最合适的光捕获结果与结晶硅薄膜的光捕获峰之间的700和1000 nm的，最重要的广泛共鸣，因为它在一个随机的纳米粒子阵列薄膜电池。只要功能细胞，制造的电浆反射是相对简单和直接在前面的章节所述。一个可能的并发症有关事实表明，纳米不仅硅细胞表面，但在金属化网格模式以及粒子形成。它可以导致有时会导致分流时，纳米粒子的相对表面覆盖过大或特别大的纳米顺带形成。为了避免分流的覆盖面应保持在50％以下的易制毒化学要保持低于20 nm的薄膜厚度，这是很容易达到标准，从14纳米前驱膜过程中，如上所述，结果在30-35％的细胞覆盖面。 电浆纳米粒子，用自己的〜30％的JSC增强，有关效率，或仅略优于色漆漫反射光散射，25％-30％，这是最简单的申请。然而，弥漫油漆反射光捕获性能，而不能进一步改善，电浆纳米粒子有一个选项被漫反射称赞放在behind，显着较高的JSC增强，从而导致高达45％，比仅由纳米粒子。这光的增强是平面晶体硅薄膜电池表现出最高的，超过最近报道由40％提高高RI介质纳米反射5。此外，超过50％，甚至更高的光增强，应该可能有如此高的国际扶轮纳米漫反射为5，而不是商业的白色油漆，。 然而，甚至45％提高约29毫安/厘米2（〜90％提高相比只有约一半通常多晶硅薄膜太阳能电池制造取得了良好的的质感superstrates，导致在JSC的PECVD反应参考平面细胞）12。更好的性能对纹理superstrates细胞主要有两种原因。首先，反射纹理前细胞表面是平面，导致更多的光线进入细胞，从而产生更多的电流比低了很多。抗反射特性的平面前表面电浆细胞需要加以改进，以使电浆光捕获与传统的纹理更具竞争力。其次，当两个单元的接口保持平面和平行，光的显着部分是国内和镜面反映没有被漫反射或纳米粒子分散在细胞内（〜17％的硅/玻璃或Si /氟化镁2接口）。这体现在细胞反射光谱或在平面细胞弥漫性或电浆反射EQE曲线干涉条纹的存在本身。少散射是指光捕获，因此，当前增强。质感细胞光散射而被反映在非并行接口没有干涉条纹，例如EQE曲线显示在 FIG。 2。 当考虑由电浆纳米粒子，以及其他手段应用于太阳能电池，如漫反射，背面的光增强，这一点很重要，要记住一个权衡之间实现较高的绝对电流或表现出较高的电流增强。更薄的设备受益于光捕获，显示出较高的电流增强，而目前本身就是明显降低为2微米，3微米厚的细胞在表1中，22.3比25.7毫安/厘米2的结果表明。同样，一个贫穷的短波（"蓝色"）的响应（如在5所描述的）的细胞有相对较高的光捕获增强，这是很重要的波长较长（"红"）具有良好的细胞反应比蓝色的反应，但后者显然可以有较高的绝对电流，从而更好的整体性能。作为光伏的主要目标是更好地performi纳克太阳能电池，应优先考虑到的光捕获方法，导致较高的绝对电流，而不是更高的电流增强。

<table border="1"><tbody><tr><td> 试剂名称 </td><td> 公司 </td><td> 目录编号 </td><td> 评论 </td></tr><tr><td>银颗粒</td><td> Sigma-Aldrich公司</td><td> 303372 </td><td> 99.99％ </td></tr><tr><td>氟化镁，随机晶体，光学级</td><td> Sigma-Aldrich公司</td><td> 378836 </td><td> &gt; = 99.99％ </td></tr><tr><td>多乐士大衣天花板涂料</td><td>多乐士</td><td></td><td> R&gt; 90％ （500-1100纳米） </td></tr></tbody></table>

polycrystalline silicon thin-film solar cells with plasmonic-enhanced light-trapping

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To compensate for lower light absorption such physically thin devices have to incorporate light-trapping which increases their optical thickness. Light scattering by textured surfaces is a common technique but it cannot be universally applied to all solar cell technologies. Some cells, for example those made of evaporated silicon, are planar as produced and they require an alternative light-trapping means suitable for planar devices. Metal nanoparticles formed on planar silicon cell surface and capable of light scattering due to surface plasmon resonance is an effective approach.
The paper presents a fabrication procedure of evaporated polycrystalline silicon solar cells with plasmonic light-trapping and demonstrates how the cell quantum efficiency improves due to presence of metal nanoparticles.
To fabricate the cells a film consisting of alternative boron and phosphorous doped silicon layers is deposited on glass substrate by electron beam evaporation. An Initially amorphous film is crystallised and electronic defects are mitigated by annealing and hydrogen passivation. Metal grid contacts are applied to the layers of opposite polarity to extract electricity generated by the cell. Typically, such a ~2 &mu;m thick cell has a short-circuit current density (Jsc) of 14-16 mA/cm2, which can be increased up to 17-18 mA/cm2 (~25% higher) after application of a simple diffuse back reflector made of a white paint.
To implement plasmonic light-trapping a silver nanoparticle array is formed on the metallised cell silicon surface. A precursor silver film is deposited on the cell by thermal evaporation and annealed at 23&deg;C to form silver nanoparticles. Nanoparticle size and coverage, which affect plasmonic light-scattering, can be tuned for enhanced cell performance by varying the precursor film thickness and its annealing conditions. An optimised nanoparticle array alone results in cell Jsc enhancement of about 28%, similar to the effect of the diffuse reflector. The photocurrent can be further increased by coating the nanoparticles by a low refractive index dielectric, like MgF2, and applying the diffused reflector. The complete plasmonic cell structure comprises the polycrystalline silicon film, a silver nanoparticle array, a layer of MgF2, and a diffuse reflector. The Jsc for such cell is 21-23 mA/cm2, up to 45% higher than Jsc of the original cell without light-trapping or ~25% higher than Jsc for the cell with the diffuse reflector only.
Introduction
Light-trapping in silicon solar cells is commonly achieved via light scattering at textured interfaces. Scattered light travels through a cell at oblique angles for a longer distance and when such angles exceed the critical angle at the cell interfaces the light is permanently trapped in the cell by total internal reflection (Animation 1: Light-trapping). Although this scheme works well for most solar cells, there are developing technologies where ultra-thin Si layers are produced planar (e.g. layer-transfer technologies and epitaxial c-Si layers) 1 and or when such layers are not compatible with textures substrates (e.g. evaporated silicon) 2. For such originally planar Si layer alternative light trapping approaches, such as diffuse white paint reflector 3, silicon plasma texturing 4 or high refractive index nanoparticle reflector 5 have been suggested.
Metal nanoparticles can effectively scatter incident light into a higher refractive index material, like silicon, due to the surface plasmon resonance effect 6. They also can be easily formed on the planar silicon cell surface thus offering a light-trapping approach alternative to texturing. For a nanoparticle located at the air-silicon interface the scattered light fraction coupled into silicon exceeds 95% and a large faction of that light is scattered at angles above critical providing nearly ideal light-trapping condition (Animation 2: Plasmons on NP). The resonance can be tuned to the wavelength region, which is most important for a particular cell material and design, by varying the nanoparticle average size, surface coverage and local dielectric environment 6,7. Theoretical design principles of plasmonic nanoparticle solar cells have been suggested 8. In practice, Ag nanoparticle array is an ideal light-trapping partner for poly-Si thin-film solar cells because most of these design principle are naturally met. The simplest way of forming nanoparticles by thermal annealing of a thin precursor Ag film results in a random array with a relatively wide size and shape distribution, which is particularly suitable for light-trapping because such an array has a wide resonance peak, covering the wavelength range of 700-900 nm, important for poly-Si solar cell performance. The nanoparticle array can only be located on the rear poly-Si cell surface thus avoiding destructive interference between incident and scattered light which occurs for front-located nanoparticles 9. Moreover, poly-Si thin-film cells do not requires a passivating layer and the flat base-shaped nanoparticles (that naturally result from thermal annealing of a metal film) can be directly placed on silicon further increases plasmonic scattering efficiency due to surface plasmon-polariton resonance 10.
The cell with the plasmonic nanoparticle array as described above can have a photocurrent about 28% higher than the original cell. However, the array still transmits a significant amount of light which escapes through the rear of the cell and does not contribute into the current. This loss can be mitigated by adding a rear reflector to allow catching transmitted light and re-directing it back to the cell. Providing sufficient distance between the reflector and the nanoparticles (a few hundred nanometers) the reflected light will then experience one more plasmonic scattering event while passing through the nanoparticle array on re-entering the cell and the reflector itself can be made diffuse - both effects further facilitating light scattering and hence light-trapping. Importantly, the Ag nanoparticles have to be encapsulated with an inert and low refractive index dielectric, like MgF2 or SiO2, from the rear reflector to avoid mechanical and chemical damage 7. Low refractive index for this cladding layer is required to maintain a high coupling fraction into silicon and larger scattering angles, which are ensured by the high optical contrast between the media on both sides of the nanoparticle, silicon and dielectric 6. The photocurrent of the plasmonic cell with the diffuse rear reflector can be up to 45% higher than the current of the original cell or up to 25% higher than the current of an equivalent cell with the diffuse reflector only.

Watch this Scientific Journal Video about Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping at JoVE.com

Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

硼，磷掺杂硅结晶，缺陷钝化和金属化层沉积制备多晶硅薄膜太阳能电池玻璃上。电浆光捕获上限〜45％的光增强扩散反射硅电池表面形成银纳米粒子的引入。

多晶硅薄膜太阳能电池电浆增强光捕获

One of major approaches to cheaper solar cells is reducing the amount of semiconductor material used for their fabrication and making cells thinner. To ...

polycrystalline-silicon-thin-film-solar-cells-with-plasmonic-enhanced

Nanyang Technological University

Research

JoVE Journal

Engineering

18.7K 次观看.  University of New South Wales. 硼，磷掺杂硅结晶，缺陷钝化和金属化层沉积制备多晶硅薄膜太阳能电池玻璃上。电浆光捕获上限〜45％的光增强扩散反射硅电池表面形成银纳米粒子的引入。

视频: Polycrystalline Silicon Thin-film Solar cells with Plasmonic-enhanced Light-trapping

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

Utilization of Plasmonic and Photonic Crystal Nanostructures for Enhanced Micro- and Nanoparticle Manipulation

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological research. Perhaps the most widely used physical force to achieve noninvasive manipulation of small particles has been dielectrophoresis(DEP).1 However, DEP on its own lacks the versatility and precision that are desired when manipulating cells since it is traditionally done with stationary electrodes. Optical tweezers, which utilize a three dimensional electromagnetic field gradient to exert forces on small particles, achieve this desired versatility and precision.2 However, a major drawback of this approach is the high radiation intensity required to achieve the necessary force to trap a particle which can damage biological samples.3 A solution that allows trapping and sorting with lower optical intensities are optoelectronic tweezers (OET) but OET's have limitations with fine manipulation of small particles; being DEP-based technology also puts constraint on the property of the solution.4,5
This video article will describe two methods that decrease the intensity of the radiation needed for optical manipulation of living cells and also describe a method for orientation control. The first method is plasmonic tweezers which use a random gold nanoparticle (AuNP) array as a substrate for the sample as shown in Figure 1. The AuNP array converts the incident photons into localized surface plasmons (LSP) which consist of resonant dipole moments that radiate and generate a patterned radiation field with a large gradient in the cell solution. Initial work on surface plasmon enhanced trapping by Righini et al and our own modeling have shown the fields generated by the plasmonic substrate reduce the initial intensity required by enhancing the gradient field that traps the particle.6,7,8 The plasmonic approach allows for fine orientation control of ellipsoidal particles and cells with low optical intensities because of more efficient optical energy conversion into mechanical energy and a dipole-dependent radiation field. These fields are shown in figure 2 and the low trapping intensities are detailed in figures 4 and 5. The main problems with plasmonic tweezers are that the LSP's generate a considerable amount of heat and the trapping is only two dimensional. This heat generates convective flows and thermophoresis which can be powerful enough to expel submicron particles from the trap.9,10 The second approach that we will describe is utilizing periodic dielectric nanostructures to scatter incident light very efficiently into diffraction modes, as shown in figure 6.11 Ideally, one would make this structure out of a dielectric material to avoid the same heating problems experienced with the plasmonic tweezers but in our approach an aluminum-coated diffraction grating is used as a one-dimensional periodic dielectric nanostructure. Although it is not a semiconductor, it did not experience significant heating and effectively trapped small particles with low trapping intensities, as shown in figure 7. Alignment of particles with the grating substrate conceptually validates the proposition that a 2-D photonic crystal could allow precise rotation of non-spherical micron sized particles.10 The efficiencies of these optical traps are increased due to the enhanced fields produced by the nanostructures described in this paper.

Plasmonic tweezers and photonic crystal nanostructures are shown to produce useful enhancements in the efficiency and orientation control of optically trapping micro- and nano-particles.

为增强微型和纳米操纵利用电浆和光子晶体纳米结构

A method to manipulate the position and orientation of submicron particles nondestructively would be an incredibly useful tool for basic biological ...

生物工程

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

合成，表征和混合金/硫化镉和Au / ZnS核/壳纳米颗粒功能化

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

化学

Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve the solar conversion efficiency of a concentrated photovoltaic system. The proposed system will also lower the solar cell cost in the concentrated photovoltaic system by replacing the expensive tandem solar cells with the cost-effective single junction solar cells. The structures and the parameters of high contrast gratings for the dispersive elements were numerically optimized. The large-area fabrication of high contrast gratings was experimentally demonstrated using nanoimprint lithography and dry etching. The quality of grating material and the performance of the fabricated device were both experimentally characterized. By analyzing the measurement results, the possible side effects from the fabrication processes are discussed and several methods that have the potential to improve the fabrication processes are proposed, which can help to increase the optical efficiency of the fabricated devices.

The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance.

制造高对比度光栅的频谱分割色散元件的聚光光伏系统

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve ...

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (&#181;c-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated &#181;c-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach.

A viable transfer printing-based methodology to introduce plasmonic metal nanostructures in solar cells is described. Using nanopillar poly(dimethylsiloxane) stamps, an Ag-based ordered nanodisk array was integrated with standard hydrogenated microcrystalline Si solar cells, which led to improved device performances due to plasmonic light trapping.

灯光诱杀银纳米结构通过转移印花在氢化微晶硅太阳能电池集成

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

全面解决方案处理的无机纳米晶体光伏器件的制造

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Morphology Control for Fully Printable Organic&#8211;Inorganic Bulk-heterojunction Solar Cells Based on a Ti-alkoxide and Semiconducting Polymer

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting material. However, fullerene derivatives are air-sensitive; therefore, air-stable material is needed as an alternative. In the present study, we propose and describe the properties of Ti-alkoxide as an alternative electron-accepting material to fullerene derivatives to create highly air-stable BHJ solar cells. It is well-known that controlling the morphology in the photoactive layer, which is constructed with fullerene derivatives as the electron acceptor, is important for obtaining a high overall efficiency through the solvent method. The conventional solvent method is useful for high-solubility materials, such as fullerene derivatives. However, for Ti-alkoxides, the conventional solvent method is insufficient, because they only dissolve in specific solvents. Here, we demonstrate a new approach to morphology control that uses the molecular bulkiness of Ti-alkoxides without the conventional solvent method. That is, this method is one approach to obtain highly efficient, air-stable, organic-inorganic bulk-heterojunction solar cells.

A method for fully printable, fullerene-free, highly air-stable, bulk-heterojunction solar cells based on Ti alkoxides as the electron acceptor and the electron-donating polymer fabrication is described here. Moreover, a method for controlling the morphology of the photoactive layer through the molecular bulkiness of the Ti-alkoxide units is reported.

基于一个钛醇盐和半导体聚合物为全可印刷有机 - 无机批量异质结太阳能电池形貌控制

The photoactive layer of a typical organic thin-film bulk-heterojunction (BHJ) solar cell commonly uses fullerene derivatives as the electron-accepting ...

Plasmonic Trapping and Release of Nanoparticles in a Monitoring Environment

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few can observe immobilized particles. Moreover, a limited number of studies have experimentally measured the exertable forces on the particles. The designs can be classified as the protruding nanodisk type or the suppressed nanohole type. For the latter, microscopic observation is extremely challenging. In this paper, a new plasmonic tweezer system is introduced to monitor particles, both in directions parallel and orthogonal to the symmetric axis of a plasmonic nanohole structure. This feature enables us to observe the movement of each particle near the rim of the nanohole. Furthermore, we can quantitatively estimate the maximal trapping forces using a new fluidic channel.

A microchip fabrication process that incorporates plasmonic tweezers is presented here. The microchip enables the imaging of a trapped particle to measure maximal trapping forces.

电浆捕获和纳米粒子的释放在监控环境

Plasmonic tweezers use surface plasmon polaritons to confine polarizable nanoscale objects. Among the various designs of plasmonic tweezers, only a few ...

Solution-Processed "Silver-Bismuth-Iodine" Ternary Thin Films for Lead-Free Photovoltaic Absorbers

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. However, poor surface morphologies and relatively high bandgap energies have limited their potential. Silver-bismuth-iodine (Ag-Bi-I) is a promising semiconductor for optoelectronic devices. Therefore, we demonstrate the fabrication of Ag-Bi-I ternary thin films using material solution processing. The resulting thin films exhibit controlled surface morphologies and optical bandgaps according to their thermal annealing temperatures. In addition, it has been reported that Ag-Bi-I ternary systems crystallize to AgBi2I7, Ag2BiI5, etc. according to the ratio of the precursor chemicals. The solution-processed AgBi2I7 thin films exhibit a cubic-phase crystal structure, dense, pinhole-free surface morphologies with grains ranging in size from 200 to 800 nm, and an indirect bandgap of 1.87 eV. The resultant AgBi2I7 thin films show good air stability and energy band diagrams, as well as surface morphologies and optical bandgaps suitable for lead-free and air-stable single-junction solar cells. Very recently, a solar cell with 4.3% power conversion efficiency was obtained by optimizing the Ag-Bi-I crystal compositions and solar cell device architectures.

Herein, we present detailed protocols for solution-processed silver-bismuth-iodine (Ag-Bi-I) ternary semiconductor thin films fabricated on TiO2-coated transparent electrodes and their potential application as air-stable and lead-free optoelectronic devices.

无铅光伏吸收剂的溶液处理 "银铋碘" 三元薄膜

Bismuth-based hybrid perovskites are regarded as promising photo-active semiconductors for environment-friendly and air-stable solar cell applications. ...

Close-Space Sublimation-Deposited Ultra-Thin CdSeTe/CdTe Solar Cells for Enhanced Short-Circuit Current Density and Photoluminescence

Developments in photovoltaic device architectures are necessary to make solar energy a cost-effective and reliable source of renewable energy amidst growing global energy demands and climate change. Thin film CdTe technology has demonstrated cost-competitiveness and increasing efficiencies due partially to rapid fabrication times, minimal material usage, and introduction of a CdSeTe alloy into a ~3 &#956;m absorber layer. This work presents the close-space sublimation fabrication of thin, 1.5 &#181;m CdSeTe/CdTe bilayer devices using an automated in-line vacuum deposition system. The thin bilayer structure and fabrication technique minimize deposition time, increase device efficiency, and facilitate future thin absorber-based device architecture development. Three fabrication parameters appear to be the most impactful for optimizing thin CdSeTe/CdTe absorber devices: substrate preheat temperature, CdSeTe:CdTe thickness ratio, and CdCl2 passivation. For proper sublimation of the CdSeTe, the substrate temperature prior to deposition must be ~540 &#176;C (higher than that for CdTe) as controlled by dwell time in a preheat source. Variation in the CdSeTe:CdTe thickness ratio reveals a strong dependence of device performance on this ratio. The optimal absorber thicknesses are 0.5 &#956;m CdSeTe/1.0 &#956;m CdTe, and non-optimized thickness ratios reduce efficiency through back-barrier effects. Thin absorbers are sensitive to CdCl2 passivation variation; a much less aggressive CdCl2 treatment (compared to thicker absorbers) regarding both temperature and time yields optimal device performance. With optimized fabrication conditions, CdSeTe/CdTe increases device short-circuit current density and photoluminescence intensity compared to single-absorber CdTe. Additionally, an in-line close-space sublimation vacuum deposition system offers material and time reduction, scalability, and attainability of future ultra-thin absorber architectures.

This work describes the complete fabrication process of thin absorber cadmium selenium telluride/cadmium telluride photovoltaic devices for enhanced efficiency. The process utilizes an automated in-line vacuum system for close-space sublimation deposition that is scalable, from fabrication of small area research devices as well as large-scale modules.

近空间升升-沉积超薄CDSeTe/CdTe太阳能电池，增强短路电流密度和光致发光

Developments in photovoltaic device architectures are necessary to make solar energy a cost-effective and reliable source of renewable energy amidst ...