Toward the Controlled Synthesis of Lead Halide Perovskite Nanocrystals

Abstract

Lead halide perovskite nanocrystals (LHP NCs) have rapidly emerged as one of the most promising materials for optical sources, photovoltaics, and sensor fields. The controlled synthesis of LHP NCs with high monodispersity and precise size tunability has been a subject of intensive research in recent years. However, due to their ionic nature, LHP NCs are usually formed instantaneously, and the corresponding nucleation and growth are difficult to monitor and regulated. In this Perspective, we summarize the representative attempts to achieve controlled synthesis of LHP NCs. We first highlight the burst nucleation and rapid growth characteristics of conventional synthesis methods. Afterward, we introduce the scheme of changing the LHP NCs into kinetically dominant, continuously size-tunable synthesis via nucleation–growth decoupling. We also summarize methods to eliminate undesired ripening effects and achieve homogeneous size distribution through rational ligand selection and solvent engineering. We hope this Perspective will facilitate the development of controlled LHP NCs synthesis protocols and advance the understanding of crystal growth fundamentals of perovskite materials.

Dimension and Thickness Control Synthesis of Strongly Confined Cesium Lead Iodide Perovskites with Excellent Two-Photon Absorption Properties

“…Due to the three-direction space coupling nature, 3D CsPbX 3 are known to exhibit low exciton binding energies, and excitons can dissociate easily to form free charge carriers. − Since low-dimensional CsPbX 3 semiconductor nanocrystals exhibit unique optical and optoelectronic properties, several research groups are working to develop three-dimensional (3D) to zero-dimensional (0D) perovskites with tunable band gaps, which have the capability to be used in different photoelectronic devices such as light-emitting diodes (LEDs), lasers, and photodetectors. − …”

“…In the case of 2D, 1D, and 0D perovskite materials, one can tune their photoluminescence (PL) and optoelectronic properties by reducing their diameter or thickness to below the excitonic Bohr radius and enhancing the quantum confinement effect. − Recent studies indicate that the quantum confinement effects and the optical properties of cesium halide perovskite materials can be tuned by controlling their dimensions, and they exhibit narrow emission peaks regardless of their lateral dimensions. − As a result, the design of 0D, 1D, and 2D nanostructures of CsPbX 3 (X = Cl, Br, or I) has stimulated huge interest via the hot injection and ligand-assisted reprecipitation method. − But until now, controlled synthesis has been challenging for low-dimensional CsPbI 3 as compared to CsPbBr 3 perovskites. − Driven by the need, in this manuscript, we report a systematic investigation of the synthesis of 0D Cs 4 PbI 6 perovskite nanocrystals (NCs), 1D CsPbI 3 nanowires (NWs), and 2D CsPbI 3 nanoplatelets (NPLs), which exhibit excellent two-photon absorption (TPA) properties. As reported in Figure , we show that temperature is the key influencing factor to develop highly confined 2D CsPbI 3 NPL, 1D CsPbI 3 NWs, and 0D Cs 4 PbI 6 NCs.…”

“…Cesium halide perovskites with the structure of CsPbX 3 (X = Cl, Br, or I) have been demonstrated to be promising materials for next-generation optoelectronic and photovoltaic devices. − We can classify CsPbX 3 (X = Cl, Br, or I) perovskite systems as zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D), depending on the connectivity of octahedral [BX 6 ] −4 in the building block. − As we and others have discussed before, for the 3D perovskite system, octahedral [BX 6 ] −4 are arranged in a 3D corner-sharing network. In the case of 3D CsPbI 3 , each cavity is occupied by one Cs-site cation. − …”

Modulation of Nucleation and Growth Kinetics of Perovskite Nanocrystals Enables Efficient and Spectrally Stable Pure-Red Light-Emitting Diodes

“…24 However, in a hot-injection reaction system, the nucleation and growth of PeNCs occur concurrently, making them indistinguishable on the time scale. 15 Therefore, we can attribute the first stage to the nucleation and growth process and the second stage to ripening process. 25 Based on the above analysis, the process of nucleation, growth, and ripening of control and optimized NCs is illustrated in Figure 1c.…”

“…Typically, the formation process of NCs can be described by the classical LaMer model, going through nucleation, growth, and ripening in turn . However, in a hot-injection reaction system, the nucleation and growth of PeNCs occur concurrently, making them indistinguishable on the time scale . Therefore, we can attribute the first stage to the nucleation and growth process and the second stage to ripening process .…”