A Demulsification–Crystallization Model for High‐Quality Perovskite Nanocrystals

Abstract

A room‐temperature technique with all‐nonpolar‐solvent, which circumvents the sensitivity of ionic perovskite to polar solvent, has become attractive for the synthesis of metal halide perovskite nanocrystals (PNCs). However, the lack of understanding of the inner mechanism, especially for the state of the precursor and the crystallization process of the PNCs, hinders further development of this technique. Here, through systematic study of the Pb precursor and in situ characterization of the PNCs, it is revealed that the reverse micelle nature of the Pb precursor exactly creates a novel demulsification‐crystallization (D–C) model, namely, a two‐stage nucleation is divided by a demulsification process for the PNCs. On this basis, a top efficiency for green light‐emitting diodes based on PNCs is obtained with a maximum external quantum efficiency of 22.5% through tailoring the D–C model using a multiple‐acid‐anion synergistic assisted strategy to obtain high‐quality PNCs. Beyond the high efficiency, the work paves the way for diverse ideas in PNC synthesis.

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

“…Note that state-of-the-art synthesis routes for highquality PNCs are devised via judicious ligand selections. 45,51 Together with these insights, the workflow demonstrated in this study is a powerful tool to construct a detailed chemical map of PNC synthesis, for bespoke tailoring their functionalities.…”

Improving Green Perovskite Nanoplate Light-Emitting Diode Performance via Precision Passivation and Phase Distribution Management

“…These defects can act as nonradiative recombination centers, leading to diminished luminous efficiency in PeLEDs. , Researchers have commonly employed molecules that incorporate phosphonate double bonds, −NH 3 groups, and cyanide moieties to passivate these defects and overcome this problem. ,− Guanidinium doping has been implemented to create an entropy-stabilized phase, enhancing stability by stabilizing undercoordinated sites . Furthermore, a synergistic strategy involving multiple acid anions has been proposed to expedite demulsification and crystallization processes, thereby contributing to the improvement of high-efficiency PeLEDs . In addition, PNPs frequently contained a substantial proportion of low-dimensional phases ( n ≤ 4), impeding efficient energy transfer within the perovskite structure. , To address this limitation, optimizing the phase distribution was introduced as a prevalent strategy to enhance the EQE of PeLEDs.…”

“…23 Furthermore, a synergistic strategy involving multiple acid anions has been proposed to expedite demulsification and crystallization processes, thereby contributing to the improvement of high-efficiency PeLEDs. 24 In addition, PNPs frequently contained a substantial proportion of low-dimensional phases (n ≤ 4), impeding efficient energy transfer within the perovskite structure. 17,25 To address this limitation, optimizing the phase distribution was introduced as a prevalent strategy to enhance the EQE of PeLEDs.…”

Evaluating Fluorinated-Aniline Units with Functionalized Spiro[Fluorene-9,9′-Xanthene] as Hole-Transporting Materials in Perovskite Solar Cells and Light-Emitting Diodes

“…For perovskite solar cells (PSCs), the power conversion efficiency (PCE) has approached 25% in a single-junction device using inorganic–organic hybrid halide perovskite materials as light absorbers [ 2 ]. Meanwhile, the fully inorganic cesium lead halide perovskites with the characteristics of a tunable emission color, high photoluminescent quantum yield as well as narrow emission line widths [ 3 ], have been considered ideal candidates for light-emitting diode applications, so-called PeLEDs [ 4 , 5 ]. Given the intrinsic semiconductor property of halide perovskite materials, the corresponding optoelectronic devices basically employ planar heterojunction architectures of the n - i - p or p - i - n form, in which the n - or p -type material is used to transport photo-generated or electro-injected charge carriers.…”