鈣鈦礦材料：深入探討從電子到清潔能源的廣泛應用

科學家正在深入研究鈣鈦礦，以便更好地了解這種材料，這種材料具有廣泛的應用，涵蓋電子、儲能、雷射、光電子、葡萄糖感測器等。

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?

科學家正在深入研究鈣鈦礦，以便更好地了解這種材料，這種材料具有廣泛的應用，涵蓋電子、儲能、雷射、光電子、葡萄糖感測器等。但它到底是什麼？

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.

鈣鈦礦是由鈣、鈦和氧組成的天然礦物，晶體結構為CaTiO₃或分子式為ABX3。 1839年在俄羅斯首次發現。與礦物鈣鈦礦具有相同晶體結構的一類材料也稱為鈣鈦礦材料。

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.

鈣鈦礦的鐵電、介電、壓電和熱電行為等優異的物理性質和化學性質（包括催化活性和氧傳輸能力）使其成為材料科學中最重要的結構類別之一。這使得它們成為燃料電池、儲存設備和光伏應用的潛在候選者。

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.

它們還可用於太陽能電池，將陽光轉化為電能，以及獲取清潔能源和降解有機污染物。

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

考慮到各種不同的行業，鈣鈦礦可能有助於進步，科學家試圖更好地了解它是有道理的。

Understanding Perovskite at Atomic Level for Better Control

在原子層面上了解鈣鈦礦以更好地控制

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.

北卡羅來納州立大學的研究人員在國家科學基金會的支持下，發現了一種透過在分子層面上研究層狀雜化鈣鈦礦（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.

這項突破使得人們能夠對 LHP 的發光特性進行前所未有的控制，並可能導致雷射和 LED 技術的重大進步。它還有望用於設計用於光伏裝置的其他材料。

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，層狀混合鈣鈦礦（LHP）已成為下一代能源和光子應用的有前景的半導體。在這裡，控制量子阱（QW）的分佈、尺寸和方向極為重要。

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 由非常薄的鈣鈦礦半導體材料片組成。這些片材透過薄的有機「間隔」層彼此分開。

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.

鑑於這些由多片鈣鈦礦和「間隔」層組成的薄膜可以有效地將電荷轉化為光，多年來，LHP 一直引起研究界的極大興趣。然而，對於如何對其進行設計以控制其性能特徵，人們的了解仍然有限。

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

為了理解它們，我們必須從量子阱開始，量子阱是卡在「間隔」層之間的半導體材料片。

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.

它們是 LHP 中形成的層。兩個原子厚的量子阱比五個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.

因為能量在分子層次上從高能結構流向低能結構，所以我們需要在2個和5個原子厚的量子阱之間有3個和4個原子厚的量子阱，讓能量有效地流動。

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

“你基本上希望有一個漸進的斜坡，能量可以級聯下來。”

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

——Kenan Gundogdu，論文的合著者、北卡羅來納州立大學物理學教授

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，人們在研究 LHP 時不斷遇到異常情況。異常現像是透過 X 射線衍射觀察到的 LHP 樣品中量子阱的尺寸分佈，這與使用光譜檢測到的不同。

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.

該論文的通訊作者、北卡羅來納州立大學材料科學與工程教授 Aram Amassian 闡釋了衍射如何表明量子阱具有兩個原子厚度並且是 3D 塊狀晶體的一部分。同時，光譜可以揭示除了三維體相的存在之外，量子阱還有兩個、三個和四個原子厚。

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，團隊開始尋找答案：為什麼兩者之間存在這種脫節，以及如何控制 LHP 中量子阱的尺寸和分佈？

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.

透過實驗，研究團隊發現奈米血小板（NPL）是關鍵因素。 NPL 是在研究人員用來製造 LHP 的溶液表面自發形成的單片鈣鈦礦材料。

“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 說：「我們發現這些奈米片本質上是在其下方形成層狀材料的模板。」他指出，奈米片的原子厚度決定了其下方 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，奈米片並不穩定，它們的厚度不斷增加，隨著時間的推移增加了新的原子層。

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

“最終，奈米片變得很厚，變成了三維晶體。”

– Amassian

– 阿瑪西亞

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，這種異常現像是由於衍射檢測到了片材的堆疊而不是奈米片，而光譜法則檢測到了孤立的片材。他補充說：

“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.”

“令人興奮的是，我們發現我們可以以受控的方式基本上阻止奈米片的生長，從本質上調整 LHP 薄膜中量子阱的大小和分佈。”

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

透過這樣做，研究人員可以獲得極好的能量級聯，這對於高再現性、低