Issue 36, 2022

Phase modulated scanning near field optical luminescence imaging as a probe of exciton dark lifetime and diffusivity in persistently luminescent micro- and nanocrystals

Abstract

Mesoscopically structured semiconductors with long-range exciton diffusion lengths are desirable for producing high efficiency photovoltaics. However, the experimental determination of the exciton diffusion length with nanoscale precision remains rare. Here, we introduce phase modulated scanning near-field optical luminescence (PM-SNOL) imaging, a new method for assessing the exciton diffusion length and relaxation time of optical materials simultaneously. Preliminary testing is executed on strontium aluminate doped with europium and dysprosium (SrAl2O4:Eu,Dy); an insulating material known to exhibit persistent luminescence. Our results demonstrate that transport between SrAl2O4:Eu,Dy and ITO nanoparticles is feasible at the metal–insulator interface without the necessity of device fabrication and performing high voltage measurements. The basic principles of PM-SNOL are explained using a model based on semiclassical quasiparticle transport for spherical crystals. We determine the exciton diffusivity, De, to be (4.2 ± 0.9) × 10−9 m2 s−1, the relaxation time, τex, to be 0.21 ± 0.04 ms and the exciton diffusion length, lD, to be 0.95 ± 0.02 μm for SrAl2O4:Eu,Dy.

Graphical abstract: Phase modulated scanning near field optical luminescence imaging as a probe of exciton dark lifetime and diffusivity in persistently luminescent micro- and nanocrystals

Article information

Article type
Paper
Submitted
23 Jun 2022
Accepted
22 Aug 2022
First published
23 Aug 2022

J. Mater. Chem. C, 2022,10, 12975-12985

Phase modulated scanning near field optical luminescence imaging as a probe of exciton dark lifetime and diffusivity in persistently luminescent micro- and nanocrystals

V. Wong, E. Yeung, M. Cole-André and G. Fanchini, J. Mater. Chem. C, 2022, 10, 12975 DOI: 10.1039/D2TC02645G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements