One-dimensional metal halide perovskite (MHP) nanowires (NWs) have recently emerged as highly promising optoelectronic materials due to their high aspect ratio, anisotropic quantum confinement, nonlinear optical response, unique mechanical flexibility, in addition to the well-known advantageous properties inherent to MHPs. In this review, we discuss the recent advancements in the synthesis, characterization, and properties of MHP NWs, particularly with their diameters below the Bohr radius (referred as ultrathin MHP NWs). Key future directions are highlighted, including refining synthesis methods for atomic-level control, understanding the growth mechanisms, improving stability through surface passivation, exploring lead-free alternatives to mitigate toxicity concerns, and achieving novel and unique properties. These advancements will enable ultrathin MHP NWs to play a pivotal role in advanced applications in various optical, optoelectronic, and photonic technologies.

Low-dimensional materials, with highly tunable electronic structures depending on their sizes and shapes, can be exploited as fundamental building blocks to construct higher-order structures with tailored emergent properties. This is akin to molecules or crystals that are assembled by atoms with diverse symmetries and interactions. Prominent low-dimensional materials developed in recent decades include zero-dimensional (0D) quantum dots, one-dimensional (1D) carbon nanotubes, and two-dimensional (2D) van der Waals materials. These materials enclose a vast diversity of electronic structures ranging from metals and semimetals to semiconductors and insulators. Moreover, low-dimensional materials can be assembled into higher-order architectures known as superlattices, wherein collective electronic and optical behaviors emerge that are absent in the individual building blocks alone. Superlattices composed of interacting low-dimensional entities thus define an ultra-manipulatable materials platform for realizing artificial structures with customizable functionalities. Here, we review significant milestones and recent progress in the field of low-dimensional materials and their superlattices. We survey recently observed exotic emergent electronic and optical properties in these materials and delve into the underlying mechanisms driving these phenomena. Additionally, we hint the future opportunities and remaining challenges in advancing this exciting area of research.

In-depth understandings of charge carrier transfer dynamics in any artificial catalytic system are of critical importance for the future design of highly efficient photocatalysts. Herein, we synthesized sub-monolayer ZnSe partial-shell coated CdSe/CdS core/shell quantum dots in a controlled fashion. The ZnSe decorated quantum dots were employed as a model catalyst for photogeneration of H₂ under light illumination. Both theoretical calculations and experimental results unravel that the growth of ZnSe partial-shell would retard the photogenerated electron transfer, and meanwhile, accelerate the corresponding hole migration process during the H₂ photogeneration reaction in the artificial photocatalytic system. As such, the performance of the relevant photocatalytic system can be modulated and optimized, and accordingly, a plausible underlying mechanism is rationalized.

The unique structure of zero-dimensional (0D) perovskite-analogues has attracted a great amount of research interest in recent years. To date, the current compositional library of 0D perovskites is largely limited to the lead-based Cs₄PbX₆ (X = Cl, Br, and I) systems. In this work, we report a new synthesis of lead-free 0D Cs₃BiX₆ (X = Cl, Br) perovskite-analogue nanocrystals (NCs) with a uniform cubic shape. We observe a broad photoluminescence peak centered at 390 nm for the 0D Cs₃BiCl₆ NCs at low temperatures. This feature originates from a self-trapped exciton mechanism. In situ thermal stability studies show that Cs₃BiX₆ NCs remain stable upon heating up to 200 °C without crystal structural degradation. Moreover, we demonstrate that the Cs₃BiX₆ NCs can transform into other bismuth-based perovskite-analogues via facile anion exchange or metal ion insertion reactions. Our study presented here offers the opportunity for further understanding of the structure-property relationship of 0D perovskite-analogue materials, leading toward their future optoelectronic applications.