# Designing for Dispersibility: How Crystallinity and Solubilizing Groups Affect Quantum Dot Dispersion in Diphenylhexatriene Matrices

## TL;DR

This study shows how the design of organic semiconductor materials affects the dispersion of quantum dots in nanocomposite films for optoelectronic applications.

## Contribution

A new design rule for improving quantum dot dispersibility in diphenylhexatriene matrices by tuning solubilizing groups.

## Key findings

- PbS quantum dots with oleic acid ligands are poorly dispersed in DPH derivatives.
- Hexanoic acid or DPH-carboxylic acid ligands significantly improve quantum dot dispersibility.
- Amorphous DPH derivatives can initially disperse QDs but later cause aggregation upon crystallization.

## Abstract

Nanocomposite
films combining organic semiconductors (OSCs) and
colloidal quantum dots (QDs) are promising systems for next-generation
optoelectronic technologies such as singlet-fission photon multiplication
(SF-PM). Here, we show that tuning the solubilizing substituents on
the high-triplet-energy SF-OSC (1E,3E,5E)-1,6-diphenylhexa-1,3,5-triene (DPH) enables
precise control over film morphology and QD dispersibility. Grazing-incidence
X-ray scattering reveals that PbS QDs ligated with oleic acid are
poorly dispersed in all DPH derivatives, whereas hexanoic acid or
DPH-carboxylic acid ligands significantly improve QD dispersibility.
A clear design rule emerges: increasing solubilizing group volume
relative to the DPH core enhances QD dispersibility, enabling well-dispersed
QDs even in highly ordered DPH matrices. An exception arises in a
derivative that forms an amorphous, nonequilibrium morphology that
fully disperses QDs, but later crystallizes, resulting in QD aggregation.
These findings show that OSC:QD nanocomposites require co-optimization
of ligand–OSC chemistry and crystallization kinetics, providing
a framework for designing efficient SF-PM and related technologies.