# Mechanistic Insights into the Seed-Mediated Growth of Perovskite Nanostructures via a Two-Step Dissolution–Recrystallization Method

## TL;DR

This study explains how perovskite nanostructures grow through a two-step process, showing how stress and timing affect their shape and size.

## Contribution

The paper introduces a mechanistic model linking compressive stress in seed grains to the controlled growth of perovskite nanostructures.

## Key findings

- Nanostructures form via seed generation followed by Ostwald ripening.
- Compressive stress from phase transitions influences nanostructure morphology.
- Dipping time and stress control shape, aspect ratio, and growth direction.

## Abstract

In this study, we investigated the formation mechanism of organo-metal halide perovskite nanostructures through a two-step process categorized as dissolution–recrystallization. It is proposed that the initial formation of nanostructures is governed by the generation of seed grains, whereas the Ostwald ripening model explains only the subsequent growth stage of these structures. We suggest that newly generated grains—formed adjacent to pre-positioned grains—experience compressive stress arising from volume expansion during the phase transition from PbI2 to the MAPbI3 perovskite phase. Owing to their unstable state, these grains may serve as effective seeds for the nucleation and growth of nanostructures. Depending on the dipping time, diverse morphologies such as nanorods, plates, and cuboids were observed. The morphology, including the aspect ratio and growth direction of these nanostructures, appears to be strongly influenced by the residual compressive stress within the seed grains. These findings suggest that the shape and aspect ratio of perovskite nanostructures can be tailored by carefully regulating nucleation, dissolution, and growth dynamics during the two-step process.