钙钛矿材料：深入探讨从电子到清洁能源的广泛应用

科学家们正在深入研究钙钛矿，以更好地了解这种材料，这种材料具有广泛的应用，涵盖电子、储能、激光、光电子、葡萄糖传感器等。

Scientists are taking a deeper dive into perovskite to better understand this material, which has vast applications covering electronics, energy storage, lasers, optoelectronics, glucose sensors, and more. But what is it exactly?

科学家们正在深入研究钙钛矿，以更好地了解这种材料，这种材料具有广泛的应用，涵盖电子、储能、激光、光电子、葡萄糖传感器等。但它到底是什么？

Perovskite is a natural mineral made of calcium, titanium, and oxygen with the crystal structure of CaTiO₃ or having the formula ABX3. It was first discovered in 1839 in Russia. A class of materials with the same crystal structure as the mineral perovskite are also known as perovskite materials.

钙钛矿是由钙、钛和氧组成的天然矿物，晶体结构为CaTiO₃或分子式为ABX3。 1839年在俄罗斯首次发现。与矿物钙钛矿具有相同晶体结构的一类材料也称为钙钛矿材料。

The exceptional physical properties such as ferroelectric, dielectric, piezoelectric, and pyroelectric behavior and chemical properties, including catalytic activity and oxygen transport capability of perovskite, make them one of the most important structure classes in material science. This makes them a potential candidate for applications in fuel cells, memory devices, and photovoltaics.

钙钛矿的铁电、介电、压电和热电行为等优异的物理性质和化学性质（包括催化活性和氧传输能力）使其成为材料科学中最重要的结构类别之一。这使得它们成为燃料电池、存储设备和光伏应用的潜在候选者。

They can also be used in solar cells to convert sunlight into electricity, as well as for the acquisition of clean energy and the degradation of organic pollutants.

它们还可用于太阳能电池，将阳光转化为电能，以及获取清洁能源和降解有机污染物。

Given all kinds of different industries, perovskite can potentially help advance, it makes sense that scientists are trying to understand it better.

考虑到各种不同的行业，钙钛矿可能有助于进步，科学家们试图更好地了解它是有道理的。

Understanding Perovskite at Atomic Level for Better Control

在原子水平上了解钙钛矿以更好地控制

Researchers from North Carolina State University, with support from the National Science Foundation, have discovered a way to create layered hybrid perovskites (LHPs) by studying them at the molecular level.

北卡罗来纳州立大学的研究人员在国家科学基金会的支持下，发现了一种通过在分子水平上研究层状杂化钙钛矿（LHP）的方法。

This breakthrough allows for unprecedented control over LHPs' light-emitting properties and can lead to significant advancements in laser and LED technologies. It also holds promise for engineering other materials for use in photovoltaic devices.

这一突破使得人们能够对 LHP 的发光特性进行前所未有的控制，并可能导致激光和 LED 技术的重大进步。它还有望用于设计用于光伏器件的其他材料。

Layered hybrid perovskites (LHPs), according to the research, have emerged as promising semiconductors for next-generation energy and photonic applications. Here, controlling the distribution, size, and orientation of quantum wells (QWs) is extremely important.

研究表明，层状混合钙钛矿（LHP）已成为下一代能源和光子应用的有前景的半导体。在这里，控制量子阱（QW）的分布、尺寸和方向极其重要。

LHPs are made up of very thin sheets of perovskite semiconductor material. These sheets are separated from each other by thin organic “spacer” layers.

LHP 由非常薄的钙钛矿半导体材料片组成。这些片材通过薄的有机“间隔”层彼此分开。

Given that these thin films of multiple sheets of perovskite and “spacer” layers can efficiently convert electrical charge into light, LHPs have been of considerable interest to the research community for years. However, there is still limited understanding of how to engineer them to control their performance characteristics.

鉴于这些由多片钙钛矿和“间隔”层组成的薄膜可以有效地将电荷转化为光，多年来，LHP 一直引起研究界的极大兴趣。然而，对于如何对其进行设计以控制其性能特征，人们的了解仍然有限。

To understand them, we have to start with quantum wells, which are sheets of semiconductor material jammed between ‘spacer' layers.

为了理解它们，我们必须从量子阱开始，量子阱是卡在“间隔”层之间的半导体材料片。

They are the layers that form in LHPs. And a two-atom thick quantum well has higher energy than the one that is five atoms thick.

它们是 LHP 中形成的层。两个原子厚的量子阱比五个原子厚的量子阱具有更高的能量。

Because energy flows from high-energy structures to low-energy structures at the molecular level, we need to have three and four atoms-thick quantum wells between the two and five atoms-thick quantum wells, allowing the energy to flow efficiently.

因为能量在分子水平上从高能结构流向低能结构，所以我们需要在2个和5个原子厚的量子阱之间有3个和4个原子厚的量子阱，让能量有效地流动。

“You basically want to have a gradual slope that the energy can cascade down.”

“你基本上希望有一个渐进的斜坡，能量可以级联下来。”

– Kenan Gundogdu, co-author of the paper and a professor of physics at NC State

——Kenan Gundogdu，该论文的合著者、北卡罗来纳州立大学物理学教授

However, people kept running into an anomaly when studying LHPs. The anomaly is the size distribution of quantum wells in an LHP sample observed through X-ray diffraction, which is different from what's detected using optical spectroscopy.

然而，人们在研究 LHP 时不断遇到异常情况。异常现象是通过 X 射线衍射观察到的 LHP 样品中量子阱的尺寸分布，这与使用光谱检测到的不同。

Aram Amassian, the paper's corresponding author and a professor of materials science and engineering at NC State University, illustrated how diffraction can indicate that quantum wells have a two-atom thickness and are part of a 3D bulk crystal. Meanwhile, spectroscopy can reveal that the quantum wells are two, three, and four atoms thick, in addition to the presence of the three-dimensional bulk phase.

该论文的通讯作者、北卡罗来纳州立大学材料科学与工程教授 Aram Amassian 阐释了衍射如何表明量子阱具有两个原子厚度并且是 3D 块状晶体的一部分。同时，光谱可以揭示除了三维体相的存在之外，量子阱还有两个、三个和四个原子厚。

So, the team went to look for answers: Why is there this disconnect between the two, and how can quantum wells' size and distribution in LHPs be controlled?

因此，团队开始寻找答案：为什么两者之间存在这种脱节，以及如何控制 LHP 中量子阱的尺寸和分布？

Through experiments, the team discovered nanoplatelets (NPLs) to be the key player. NPLs are individual sheets of perovskite material that form spontaneously on the surface of the solution the researchers used to create LHPs.

通过实验，研究小组发现纳米血小板（NPL）是关键因素。 NPL 是在研究人员用来制造 LHP 的溶液表面自发形成的单片钙钛矿材料。

“We found that these nanoplatelets essentially serve as templates for layered materials that form under them,” said Amassian, noting that the atomic thickness of nanoplatelets dictates the thickness of LHP beneath it.

Amassian 说：“我们发现这些纳米片本质上是在其下方形成层状材料的模板。”他指出，纳米片的原子厚度决定了其下方 LHP 的厚度。

However, the nanoplatelets aren't stable, and their thickness keeps on growing, adding new layers of atoms over time.

然而，纳米片并不稳定，它们的厚度不断增加，随着时间的推移增加了新的原子层。

“Eventually, the nanoplatelet grows so thick that it becomes a three-dimensional crystal.”

“最终，纳米片变得很厚，变成了三维晶体。”

– Amassian

– 阿马西亚

So, the anomaly was due to diffraction detecting the stacking of sheets but not nanoplatelets, while optical spectroscopy detects isolated sheets. He added:

因此，这种异常现象是由于衍射检测到了片材的堆叠而不是纳米片，而光谱法检测到了孤立的片材。他补充道：

“What's exciting is that we found we can essentially stop the growth of nanoplatelets in a controlled way, essentially tuning the size and distribution of quantum wells in LHP films.”

“令人兴奋的是，我们发现我们可以以受控的方式基本上阻止纳米片的生长，从本质上调整 LHP 薄膜中量子阱的大小和分布。”

By doing so, researchers can attain superb energy cascades, which are essential for high reproducibility, low

通过这样做，研究人员可以获得极好的能量级联，这对于高再现性、低