Diroll Benjamin T, Guzelturk Burak, Po Hong, Dabard Corentin, Fu Ningyuan, Makke Lina, Lhuillier Emmanuel, Ithurria Sandrine
Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States.
X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States.
Chem Rev. 2023 Apr 12;123(7):3543-3624. doi: 10.1021/acs.chemrev.2c00436. Epub 2023 Feb 1.
The field of colloidal synthesis of semiconductors emerged 40 years ago and has reached a certain level of maturity thanks to the use of nanocrystals as phosphors in commercial displays. In particular, II-VI semiconductors based on cadmium, zinc, or mercury chalcogenides can now be synthesized with tailored shapes, composition by alloying, and even as nanocrystal heterostructures. Fifteen years ago, II-VI semiconductor nanoplatelets injected new ideas into this field. Indeed, despite the emergence of other promising semiconductors such as halide perovskites or 2D transition metal dichalcogenides, colloidal II-VI semiconductor nanoplatelets remain among the narrowest room-temperature emitters that can be synthesized over a wide spectral range, and they exhibit good material stability over time. Such nanoplatelets are scientifically and technologically interesting because they exhibit optical features and production advantages at the intersection of those expected from colloidal quantum dots and epitaxial quantum wells. In organic solvents, gram-scale syntheses can produce nanoparticles with the same thicknesses and optical properties without inhomogeneous broadening. In such nanoplatelets, quantum confinement is limited to one dimension, defined at the atomic scale, which allows them to be treated as quantum wells. In this review, we discuss the synthetic developments, spectroscopic properties, and applications of such nanoplatelets. Covering growth mechanisms, we explain how a thorough understanding of nanoplatelet growth has enabled the development of nanoplatelets and heterostructured nanoplatelets with multiple emission colors, spatially localized excitations, narrow emission, and high quantum yields over a wide spectral range. Moreover, nanoplatelets, with their large lateral extension and their thin short axis and low dielectric surroundings, can support one or several electron-hole pairs with large exciton binding energies. Thus, we also discuss how the relaxation processes and lifetime of the carriers and excitons are modified in nanoplatelets compared to both spherical quantum dots and epitaxial quantum wells. Finally, we explore how nanoplatelets, with their strong and narrow emission, can be considered as ideal candidates for pure-color light emitting diodes (LEDs), strong gain media for lasers, or for use in luminescent light concentrators.
半导体胶体合成领域诞生于40年前，由于在商业显示器中使用纳米晶体作为磷光体，该领域已达到一定的成熟水平。特别是，基于镉、锌或汞硫族化合物的II-VI族半导体现在可以合成出具有定制形状、通过合金化实现的成分，甚至可以合成纳米晶体异质结构。十五年前，II-VI族半导体纳米片为该领域注入了新思想。事实上，尽管出现了其他有前景的半导体，如卤化物钙钛矿或二维过渡金属二硫属化物，但胶体II-VI族半导体纳米片仍然是在宽光谱范围内能够合成的最窄的室温发射体之一，并且它们随时间表现出良好的材料稳定性。这类纳米片在科学和技术上都很有趣，因为它们在胶体量子点和外延量子阱所预期的光学特性和生产优势的交叉点上展现出独特的性质。在有机溶剂中，克级合成能够生产出具有相同厚度和光学性质且无不均匀展宽的纳米颗粒。在这类纳米片中，量子限制仅限于原子尺度定义的一维，这使得它们可以被视为量子阱。在这篇综述中，我们讨论了这类纳米片的合成进展、光谱性质及应用。涵盖生长机制，我们解释了对纳米片生长的深入理解如何推动了具有多种发射颜色、空间局域激发、窄发射和宽光谱范围内高量子产率的纳米片及异质结构纳米片的发展。此外，纳米片具有大的横向延伸、薄的短轴以及低介电环境，能够支持一个或几个具有大激子结合能的电子-空穴对。因此，我们还讨论了与球形量子点和外延量子阱相比，纳米片中载流子和激子的弛豫过程及寿命是如何被改变的。最后，我们探讨了具有强而窄发射的纳米片如何能够被视为纯色发光二极管（LED）的理想候选材料、激光的强增益介质或用于发光光集中器。
