# Dimensionality Control of Inorganic and Hybrid Perovskite Nanocrystals by Reaction Temperature: From No‐Confinement to 3D and 1D Quantum Confinement

## TL;DR

This paper shows how changing reaction temperature affects the shape and quantum confinement of perovskite nanocrystals, enabling control over their properties.

## Contribution

A scalable, inert-gas-free method to control the dimensionality and morphology of perovskite nanocrystals via reaction temperature.

## Key findings

- Lowering reaction temperature transforms CsPbBr3 nanocubes into 0D and 2D structures with quantum confinement.
- Higher temperatures produce rare hexapod-shaped CsPbBr3 nanocrystals.
- The method works for both inorganic and hybrid perovskites without size-selective separation.

## Abstract

This work focuses on the systematic investigation of the shape, size, and composition‐controlled synthesis of perovskite nanocrystals (NCs) under inert gas‐free conditions and using pre‐synthesized precursor stock solutions. In the case of CsPbBr3 NCs, we find that the lowering of reaction temperature from ∼175 to 100 °C initially leads to a change of morphology from bulk‐like 3D nanocubes to 0D nanocubes with 3D‐quantum confinement, while at temperatures below 100 °C the reaction yields 2D nanoplatelets (NPls) with 1D‐quantum confinement. However, to our surprise, at higher temperatures (∼215 °C), the reaction yields CsPbBr3 hexapod NCs, which have been rarely reported. The synthesis is scalable, and their halide composition is tunable by simply using different combinations of precursor solutions. The versatility of the synthesis is demonstrated by applying it to relatively less explored shape‐controlled synthesis of FAPbBr3 NCs. Despite the synthesis carried out in the air, both the inorganic and hybrid perovskite NCs exhibit nearly‐narrow emission without applying any size‐selective separation, and it is precisely tunable by controlling the reaction temperature.

The morphology of both inorganic and hybrid halide perovskite nanocrystals is tunable from 3D nanocubes with no‐confinement to 0D nanocubes and 2D nanoplatelets with 3D and 1D‐quantum confinement, respectively by a decrease of the reaction temperature in the hot‐plate approach under inert gas‐free conditions. The synthesis is scalable, and their halide composition is tunable by simply using different combinations of precursor stock solutions.