# Refractive Index and Strain Modulation Tailor the Afterglow of Nanocomposite Films

## TL;DR

Scientists developed a new way to control the glowing properties of nanocomposite films by adjusting their refractive index and strain, enhancing brightness and afterglow.

## Contribution

A novel strategy to manipulate afterglow by tuning refractive index and strain without changing material composition.

## Key findings

- Nanocomposite films with tunable refractive indices (1.45 to 1.7) increased luminescence and afterglow brightness by 1.7-fold.
- Strain from SiO2 altered the intrinsic charging rate of ZnGa2O4:Cr3+ nanocrystals, affecting afterglow kinetics.

## Abstract

Tailoring the unique
delayed and long-lasting luminescence
of persistent
phosphors is crucial for their application in anticounterfeiting,
data storage, imaging displays, and AC-driven lighting. We introduce
a novel strategy to achieve this by modifying the refractive index
of persistent phosphor transparent coatings. Specifically, we developed
ZnGa2O4:Cr3+/SiO2 nanocomposite
films with tunable refractive indices from 1.45 to 1.7. This tunability
allowed us to precisely control the Cr3+ radiative decay
rate, resulting in a substantial 1.7-fold increase in both luminescence
and afterglow brightness. Furthermore, our approach uniquely influences
the intrinsic charging rate of the phosphor, a mechanism attributed
to the strain induced on the ZnGa2O4:Cr3+ nanocrystals by the presence of SiO2. This work
demonstrates an unprecedent ability to manipulate the afterglow kinetics
without altering the material composition, opening new avenues for
designing and optimizing persistent luminescence materials.