Extraordinary Interfacial Stitching between Single All-Inorganic Perovskite Nanocrystals

Abstract

All-inorganic cesium lead halide perovskite nanocrystals are extensively studied because of their outstanding optoelectronic properties. Being of a cubic shape and typically featuring a narrow size distribution, CsPbX3 (X = Cl, Br, and I) nanocrystals are the ideal starting material for the development of homogeneous thin films as required for photovoltaic and optoelectronic applications. Recent experiments reveal spontaneous merging of drop-casted CsPbBr3 nanocrystals, which is promoted by humidity and mild-temperature treatments and arrested by electron beam irradiation. Here, we make use of atom-resolved annular dark-field imaging microscopy and valence electron energy loss spectroscopy in a state-of-the-art low-voltage monochromatic scanning transmission electron microscope to investigate the aggregation between individual nanocrystals at the atomic level. We show that the merging process preserves the elemental composition and electronic structure of CsPbBr3 and takes place between nanocrystals of different sizes and orientations. In particular, we reveal seamless stitching for aligned nanocrystals, similar to that reported in the past for graphene flakes. Because the crystallographic alignment occurs naturally in drop-casted layers of CsPbX3 nanocrystals, our findings constitute the essential first step toward the development of large-area nanosheets with band gap energies predesigned by the nanocrystal choice—the gateway to large-scale photovoltaic applications of inorganic perovskites.

Self-Patterned CsPbBr3 Nanocrystals for High-Performance Optoelectronics

“…Oriented CsPbX 3 nanostructures, such as one-dimensional (1D) nanowires, nanocrystals or two-dimensional (2D) nanosheets, have been synthesized for this purpose [15][16][17]18 . Nevertheless, these methods have failed to eliminate the grain boundaries that can hinder carrier transport.…”

Atomic Structure and Electrical Activity of Grain Boundaries and Ruddlesden–Popper Faults in Cesium Lead Bromide Perovskite

“…Besides point defects, the solution‐based growth also leads to polycrystalline materials with abundant grain boundaries (GBs) and other planar faults . There have been diverging experimental reports on the electrical activity of GBs in lead‐halide perovskites.…”

Highly Stable Perovskite Supercrystals via Oil-in-Oil Templating

“…This is different from our previous work, where we rather observed the electron-beam irradiation to enhance the stability of NCs. 28 The good stability of the SCs is also reflected in their optical properties, as shown in Figure 4 d. After 39 d at ambient conditions, ∼45% of the PL QY is preserved for all measurements. These results are in stark contrast to the rather rapid decay of morphology and PL reported previously for perovskite cuboidal superstructures, which merged into single nanoplatelets within two weeks.…”