First evidence of macroscale single crystal ion exchange found in lead halide perovskites

Abstract

Ion exchange is classified as a reaction that may be performed among nanocrystals. Here, we discovered that methylammonium lead bromide macroscale perovskite single crystals may exchange ions with the environment while maintaining their original morphology. Iodide replaced bromide and was detected even in the very center of a previously pure macroscale MAPbBr3 single crystal. Additionally, the entrance of chloride into the crystal is energetically favorable and most bromides were exchanged, yet kinetic factors hindered Cs+ entry and Pb2+ by Sn2+ substitution. Furthermore, grinding different single crystals together revealed swift I/Br exchange. Clear differences in comparison with nanomaterials, along with density functional theory calculations, shed light on the nature of ion‐exchange reactions in perovskite single crystals. This work provides first evidence of these halide exchange reactions in macroscale perovskite single crystals. These results offer a new perspective on ion‐exchange reaction and pave a path toward synthesis of inhomogeneous single crystals.

Study of Electron Transport Layer‐Free and Hole Transport Layer‐Free Inverted Perovskite Solar Cells

“…In addition, the morphology of the crystals also changes. Figure 3c shows a well‐defined crystal with a “lego‐like” pattern (which was reported previously [ 42 ] ), whereas in Figure 3b, in the case of HTL‐free cells, the crystals are less well defined. The morphology of the perovskite deposited on other HTLs (i.e., P3HT and CuSCN) was studied, as shown in Figure S4, Supporting Information.…”

Indication of CsPbBr3 inclusions in zero dimensional Cs4PbBr6 perovskite single crystals by alkylammonium post‐treatment

“…Following, four samples of 0.15 g of Cs 4 PbBr 6 SCs were ground manually for 20 seconds using mortar and pestle under different conditions (see schematic illustration in Figure 1A). [ 28 ] The four different samples of Cs 4 PbBr 6 were ground under four different conditions: (1) dry, (2) in the presence of 500 L of absolute methanol (MeOH), (3) in the presence of 500 L of N ‐octyl monoammonium bromide (C8MABr) solution in absolute MeOH, and (4) in the presence of 500 L of 1,8‐octyl diammonium bromide (C8DABr) solution in absolute MeOH. Spontaneous evaporation of the MeOH took place under ambient atmosphere at room temperature.…”

Ion exchange for halide perovskite: From nanocrystal to bulk materials

“…This is the first report of the formation of high-quality single crystal heterojunctions in organic halide perovskite materials. Similarly, Etgar et al [163] discovered that methylammonium lead bromide macroscale perovskite single crystals may exchange ions with MAI/MACl ethanol solution of while maintaining their original morphology. The work provided first evidence of halide exchange reactions in macroscale perovskite single crystals.…”