Atomic Insights of Stable, Monodispersed CsPbI_3−xBr_x (x = 0, 1, 2, 3) Nanocrystals Synthesized by Modified Ligand Cell

Abstract

Synthesis of monodispersed, stable halide, and mixed halide perovskite nanocrystals by hot‐injection approach is still challenging due to the fast reaction kinetics and unrevealed ligand chemistry. The atomic scale imaging of perovskite nanocrystals using transmission electron microscopy (TEM) is also challenging because of their structural degradation due to high electron dose and soft nature of perovskites. Here, a novel technique is proposed to synthesize pure cubic phase, monodispersed, stable CsPbX3 (X = I/Br) nanocrystals by simply modifying ligand chemistry using olive oil, which also leads to realization of tuneable composition mixed halide perovskites by simple physical mixing. Here, the atomic scale images and the probable distribution of Cs, Pb, and I/Br atoms in single halide and mixed halide perovskites via high‐resolution TEM microscopy are presented. The estimated atomic distance (PbPb and PbI/Br) is strongly corroborated with the VESTA structure. Interestingly, the lattice constant (d‐value) of the synthesized nanocrystals is smaller (≈3%) than the theoretical predicted one, leading to a higher phase stability in laboratory ambient conditions (45–55% humidity, 300 K). The theoretical analysis using density functional theory enlightens the understanding of higher stability of CsPbI2Br along with the maximum optical absorption in the visible regime, as a preferable material for the photovoltaic applications.

Ligand‐Mediated Revival of Degraded α‐CsPbI3 to Stable Highly Luminescent Perovskite

“…It is well known that the transformation from Cs 4 PbI 6 !CsPbI 3 is feasible in the presence of a suitable ligand. [19,40] Hence, the addition of DSH to the aged sample eventually led to the revival of the thermodynamically stable cubic phase transformed from the trigonal Cs-rich Cs 4 PbI 6 .…”

Heterojunction Engineering Enhanced Self‐Polarization of PVDF/CsPbBr3/Ti3C2Tx Composite Fiber for Ultra‐High Voltage Piezoelectric Nanogenerator

“…High-resolution transmission electron microscopy (HRTEM) images demonstrate that Ti 3 C 2 T x nanosheets retain the hexagonal crystal structure of the parent Ti 2 AlC phase (the insert of Figure 2k). The crystal plane spacing of 0.21 and 0.26 nm are corresponding to the (220) crystal plane of CsPbBr 3 [27] and (100) crystal plane of Ti 3 C 2 T x [28] (Figure 2l). The white interface implies the formation of Ti 3 C 2 T x -CsPbBr 3 heterojunction.…”

Various approaches to synthesize water-stable halide PeNCs

“…Mixing a small fraction of stable Cs + with the FA or MA-based perovskite successfully suppressed the formation of the optically inactive δ-phase by adjusting the GTF factor. 72 Park et al demonstrated that when 10% of FA + was replaced by Cs + in FAPbI 3 the water stability was improved and photodegradation under constant UV illumination was minimized. 73 Under continuous UV illumination (intensity = ∼100 mW cm −2 ) for 19 h, the FAPbI 3 film showed 86% degradation, but the FA 0.9 Cs 0.1 PbI 3 film showed 65% degradation.…”