# Investigating the Role π‑Rich Solvents Play in the Growth of Cesium Lead Bromide Nanocrystals

## TL;DR

This study explores how different solvents affect the growth and properties of cesium lead bromide nanocrystals.

## Contribution

The novel contribution is the investigation of π-rich solvents' role in shaping nanocrystal morphology and optical properties.

## Key findings

- π-rich solvents like dibenzyl ether and diphenyl ether influence the formation of plumbate precursors and nanocrystal morphology.
- Room-temperature synthesis with π-rich solvents yields blue-emitting rod-like nanocrystals, while hot-injection produces green-emitting platelets.
- Room-temperature products show surface defects and lower quantum yields compared to hot-injection products.

## Abstract

In this report, the role that a high-boiling-point solvent
type
plays on the nucleation and growth, morphology, and crystal-phase
transformation of cesium lead bromide nanocrystals (CsPbBr3) is studied. The CsPbBr3 products were compared between
a one-pot growth mechanism at room temperature (RT) versus a hot-injection
mechanism (HI) control using dibenzyl ether (DBE), diphenyl ether
(DPE), dioctyl ether (DOE), or 1-octadecene (ODE). The coordination
between these solvents and the PbBr2 salt precursors resulted
in different plumbate [PbSBr
n
]2–n
precursors being formed. The S-to-Pb2+ coordination within [PbSBr
n
]2–n
was probed by UV–vis and solvent-phase 207Pb NMR, both of which showed considerable coordination between
[PbSBr
n
]2–n
and the π-rich DBE and DPE, whose reactivity affected
CsPbBr3 growth. The effect was more pronounced for CsPbBr3 prepared via RT, where the morphology was tunable, with π-rich
solvents producing thin rod-like CsPbBr3 with a blue emission,
compared to the green-emitting thicker platelets formed via HI. While
XRD showed crystalline products for both RT and HI, with orthorhombic
and cubic forms, respectively, the RT products had considerable surface
defects, as was indicated by lower quantum yields, and to understand
this the photoluminescent lifetimes were measured by time-correlated
single photon counting.