Understanding the Ligand-Assisted Reprecipitation of CsPbBr3 Perovskite Nanocrystals via High Throughput Robotic Synthesis Approach

Abstract

Inorganic cesium lead bromide (CsPbBr3) perovskite nanocrystals (PNCs) have rendered promising performances in various optoelectronic applications. In contrast to the complex hot-injection synthesis, the ligand-assisted reprecipitation (LARP) method renders a simple route enabling mass-production of high-quality PNCs. However, LARP synthesis is susceptible, and thus, little has been deeply understood about how to control the growth of PNCs and the optical characteristics of the PNCs. Herein, by implementing a high-throughput automated experimental platform, we explore the growth behaviors and colloidal stability of the LARP-synthesized PNCs. Using two distinctive acid-base pairs - oleic acid-oleylamine and octanoic acid-octylamine, we systematically explore the influence of ligands - chain lengths, concentration and ratios - on the particle growths and consequent functionalities of the PNCs. We observe that the short-chain ligands cannot make functional PNCs with desired sizes and shapes, whereas the long-chain ligands provide homogeneous and stable PNCs. The PNCs transform into a Cs-rich non-perovskite structure with poorer emission functionalities and larger size distributions by employing excessive amines or polar antisolvent. This proposes that the diffusion of the ligands in a reaction system crucially determines the structures and functionalities of the PNCs. Our high-throughput exploration provides a detailed guidance on synthesis routes for desired PNCs.

Accelerating materials discovery by high-throughput GIWAXS characterization of quasi-2D formamidinium metal halide perovskites

“…Herein, we implement a high-throughput automated experimental workflow to systematically explore the phase heterogeneity of quasi-2D MHPs as a function of 2D:3D compositional ratios. 21,31 By using a robotic pipetting platform, an array of 96 quasi-2D MHP films are quickly synthesized, and the phase distributions and their time-evolutions in each filmalong the vertical directions and compositional changesare autonomously characterized via photoluminescence (PL) spectroscopy. A machine learning (ML)-based analysis effectively reveals the compositional and geometric constitutions of the associated phases in the system from the massive PL dataset, the amount of which is impossible for individual to manually analyze.…”

Lead-Free Halide Perovskites for Photocatalysis via High-Throughput Exploration

“…Combinatorial mixing and spotting involve presynthesized components mixed in various ratios and spotted onto a support to generate a diverse library. 71 Solution-phase combinatorial synthesis 72 involves a well-plate-based pipetting method that controls the dilution process and also the endmember concentrations. The room temperature-based solution-processing method offers scalability, making it an excellent choice for industrial-level production of Pb-free NCs.…”

High-Throughput Automated Exploration of Phase Growth Kinetics in Quasi-2D Formamidinium Metal Halide Perovskites

“…16 Several efforts were attempted to regulate the multi-phase emergence via spacer engineering, 17 optimal 2D:3D MHP ratio, 13 and additive engineering. 3 Recently, implementation of high-throughput robotic synthesis platforms have opened a new avenue of materials explorations and processing optimizations, 18 not only accelerating the discovery of functional MHP compositions (particularly in 3D system) but also provides comprehensive insights into the phase distributions, physical properties and stability of the complex quasi-2D MHP systems. [19][20][21] Nevertheless, all those strategies have exhibited limited success, which could be attributed to a lack in understanding of the phase growth behaviors of the complex quasi-2D MHP system.…”