将极其薄的材料堆叠在彼此之上，可以创造出具有令人兴奋的新属性的新材料。亚博网站下载但是，建造这些堆栈的最成功的过程可能是乏味和不完美的，并且不适合大规模生产。
现在，由斯坦福教授Hemamala Karunadasa领导的团队创造了一种更简单，更快的方法。它们生长了最受欢迎的材料之一，称为钙钛矿的二层，与大晶体中的其他材料薄层交织在一起。亚博网站下载
组件发生在小瓶中，其中层的化学成分在水中滚动，以及指导动作的杠铃形分子。杠铃的每一端都带有一个模板，用于生长一种类型的层。随着层结晶（类似于制作岩石糖果的过程），杠铃会以适当的顺序自动将它们连接在一起。
“真正酷的是，这些复杂的分层材料自发结晶，”亚博网站下载在研究时期，迈克尔·奥布里（Michael Aubrey）说，他是卡鲁纳达萨（Karunadasa）实验室的博士后研究员。
The researchers say their method lays the foundation for making a wide array of complex semiconductors in a much more deliberate way, including combinations of materials that have not been known to pair up in crystals before. They described the work in a paper published in自然今天。
"We are pretty thrilled about this general strategy that can be expanded to so many kinds of materials,"能源部SLAC国家加速器实验室的斯坦福材料与能源科学研究所（Simes）的调查员Karunadasa说。亚博网站下载亚博老虎机网登录
她说：“而不是在时间上操纵材料一层，我们只是把离子扔亚博网站下载进一锅水中，让离子组装他们想要组装的方式。我们可以将这些东西划分，我们知道，我们知道原子在晶体中的位置。这种精确度使我知道层之间的界面是什么样子，这对于确定材料的电子结构（其电子如何行为）很重要”
易于制作，很难堆叠
奥布里说，自1900年代以来，已经在水中组亚博网站下载装了卤化钙钛矿 - 具有与天然钙钛矿矿物质相同的八人体结构的材料。它们具有有效吸收太阳能电池并将其转换为电能的很大潜力，但众所周知，它们也不稳定，尤其是在光电燃料中运行的炎热，光明的环境中。
Layering perovskites with other materials could combine their properties in ways that improve their performance in specific applications. But an even more exciting prospect is that entirely new and unexpected properties could emerge at the interfaces where layers meet; for instance, scientists have previously discovered that stacking thin films of two different types of insulators can create an electrical conductor.
It's hard to predict which combinations of materials will turn out to be interesting and useful. What's more, making thinly layered materials has been a slow, painstaking process. Layers are generally made by peeling films just one or two atoms thick, one at a time, from a bigger chunk of material. That's how graphene is made from graphite, a pure form of carbon used in pencil leads. In other cases, these thinly layered materials are made in tiny batches at very high temperatures.
"The way they're made has not been scalable and sometimes even difficult to reproduce from one batch to another,"Karunadasa said.“剥下只有一个或两个原子厚的层是专业的工作；这不是您和我可以进入实验室的东西。这些床单就像一张非常灵活的牌一样；当您取出一张纸牌时，可能会皱眉或扣子。因此，很难知道最终堆栈的确切结构。对于看起来像我们在本研究中创建的材料的材料几乎没有先例。”亚博网站下载
岩石糖果合成
这项工作是从研究合着者亚伯拉罕·萨尔迪瓦·瓦尔德斯（Abraham Saldivar Valdes）的研究中发展出来的，他当时是卡鲁纳达萨小组的研究生。在几年的过程中，他开发了一种新的方法来使分层结构组装自己，这是研究生Bridget Connor进一步扩展的。同时，奥布里（Aubrey）发现它们的原子薄层具有与已经知道的特性的3D相似材料的结构相同的结构，并且他跟踪了两个不同层如何稍微扭曲以共享界面。亚博网站下载他还在研究生Kurt Lindquist的帮助下研究了最终产品的光学特性。
Creating the layered structures"is the same exact process as making rock candy, where you drop a wooden dowel into saturated sugar solution and the candy crystals seed themselves onto the dowel,"奥布里说。"But in this case the starting materials are different and you don't need a dowel – crystals will start forming in water or on the surface of the glass vial."
该团队制作了六种自组装材料，将钙壶与金属卤化物或金属硫化物交织在一起，并在Doe亚博网站下载's Lawrence Berkeley National Laboratory的Advanced Light Source中对其进行了检查。
In most of the structures, the barbell molecules held the layers slightly apart. But in one of them the barbell molecules brought the layers directly into contact with each other so they could form chemical bonds.
“我们对连接层连接的这种类型的结构特别兴奋，因为它可能导致新兴特性，例如分布在两层之间的电子激发，”Karunadasa said.
"And in this particular case, when we hit the material with light to free electrons and create positively charged holes, we found the electrons mostly in one type of layer and the holes mostly in the other. This is important in our field, because it allows you to tune those two environments to get the electronic behavior you want."
奥布里说，有了新技术，“我们现在正在进行大量探索，以发现可以使用哪种结构进行。”
Marina Filip and Jeffrey Neaton from the University of California, Berkeley and Berkeley Lab performed the electronic structure calculations in this work. This research was funded by the DOE Office of Science. ALS is an Office of Science user facility, as are two other facilities where computing was done for this research: the National Energy Research Scientific Computing Center (NERSC) and the Oak Ridge Leadership Computing Facility.
来源：https://www6.slac.stanford.edu/