Ion exchange for halide perovskite: From nanocrystal to bulk materials

Abstract

Halide perovskite, an ionic semiconductor, with the typically structural composition of ABX 3 has become the extremely popular star in optoelectronics due to its superior photophysical properties and easily solution processing. In comparison with the traditional semiconductors, the perovskite possesses a low crystal formation energy with facile solution synthesis, which results into its soft and dynamic crystal lattice. Therefore, the post-synthetic composition tuning via ion exchange has been proved to be an effective technique to introduce heteroatoms into perovskite lattice. In this review, we summarize the recent progress on ion exchange of halide perovskites, including mechanisms, methods, as well as different scales from low-dimensional nanoscale to bulk crystal. Besides, we also briefly discuss the prospective of ion exchange for halide perovskites, and hope it benefit for the structural design and compositional optimization in halide perovskites for various optoelectronic applications.

Free-Standing Metal Halide Perovskite Nanowire Arrays with Blue-Green Heterostructures

“…Instead, several groups have investigated the halide or anion exchange method, where the halide atoms are replaced after crystal growth. 25 , 26 Single nanowire or horizontal nanowire arrays with heterojunctions have been made by solid diffusion, 27 solution, 28 , 29 or vapor anion exchange. 30 Electron beam lithography was usually required to selectively expose parts of the nanowires before the anion exchange, 28 , 29 but such an approach is not scalable for large-area devices.…”

“…Heterostructures are essential for electronic and optoelectronic devices, thanks to their ability to control the electronic band structure, and the ability to create MHP nanowire heterostructures would be highly desirable due to their potential applications such as multicolor displays, self-powered photodetectors, and large-scale electronic circuits. − However, the epitaxial growth used to create heterostructures in traditional semiconductors is very difficult in MHPs, since the liquid precursor solution of the new layer tends to dissolve previous layers. Instead, several groups have investigated the halide or anion exchange method, where the halide atoms are replaced after crystal growth. , Single nanowire or horizontal nanowire arrays with heterojunctions have been made by solid diffusion, solution, , or vapor anion exchange . Electron beam lithography was usually required to selectively expose parts of the nanowires before the anion exchange, , but such an approach is not scalable for large-area devices.…”

One-Dimensional Highly-Confined CsPbBr3 Nanorods with Enhanced Stability: Synthesis and Spectroscopy

“…Varying the composition can usually be done by direct synthesis with a combination of different PbX 2 (X = Cl, Br, I) precursors or by post synthetic anion exchange starting from CsPbBr 3 . , However, our attempts to synthesize perovskite NRs of other halide compositions were not as successful as CsPbBr 3 , possibly due to the different reactivity of Pb complexes with ligand mixtures. Instead, we employed a well-documented anion exchange reaction to tune the halide composition, starting from the directly-synthesized CsPbBr 3 NRs.…”

In Situ Solution-Grown Halide Perovskite Single Crystals with Epitaxial Heterojunction Structures for Efficient Photodetection

“…Recently, the use of a heterojunction structure has been demonstrated to shorten the carrier transport distance in the perovskite films, thus reducing carrier losses . Although the PSC heterojunctions have been achieved with several synthetic routes, including ion exchange, epitaxial growth, and spontaneous phase separation, − to precisely control the PSC heterojunction growth and to reveal its influence on the PSC heterojunction-based devices are still challenging.…”