Dispersity

Physics

Quantum dot

Kinetics

Nanotechnology

Nanocrystal

Organic chemistry

Polymer chemistry

Formamidinium

Nucleation

Crystallography

Absorption (acoustics)

Engineering

Perovskite (structure)

Physical chemistry

Chemical physics

Composite material

Halide

Ionic bonding

Inorganic chemistry

Chemistry

Materials science

Colloid

Quantum mechanics

Photoluminescence

Chemical engineering

Optoelectronics

Science

Colloidal lead halide perovskite nanocrystals are of interest as photoluminescent quantum dots (QDs) whose properties depend on the size and shape. They are normally synthesized on subsecond time scales through hard-to-control ionic metathesis reactions. We report a room-temperature synthesis of monodisperse, isolable, spheroidal APbBr3 QDs ("A" indicates cesium, formamidinium, and methylammonium) that are size tunable from 3 to >13 nanometers. The kinetics of both nucleation and growth are temporally separated and substantially slowed down by the intricate equilibrium between the precursor (PbBr2) and the A[PbBr3] solute, with the latter serving as a monomer. QDs of all these compositions exhibit up to four excitonic transitions in their linear absorption spectra, and we demonstrate that the size-dependent confinement energy for all transitions is independent of the A-site cation.

Controlling the nucleation and growth kinetics of lead halide perovskite quantum dots