On the Existence of Excitonic Signatures in the Optical Response of Metal-Organic Frameworks: Comment on "van der Waals Metal-Organic Framework as an Excitonic Material for Advanced Photonics"

R G Polozkov; N Y Senkevich; I I Vrubel; I A Shelykh

doi:10.1002/adma.201702463

On the Existence of Excitonic Signatures in the Optical Response of Metal-Organic Frameworks: Comment on "van der Waals Metal-Organic Framework as an Excitonic Material for Advanced Photonics"

Adv Mater. 2017 Dec;29(47). doi: 10.1002/adma.201702463.

Authors

R G Polozkov¹, N Y Senkevich¹, I I Vrubel¹, I A Shelykh^{1

2}

Affiliations

¹ ITMO University, Saint Petersburg, 197101, Russia.
² Science Institute, University of Iceland, Dunhagi 3, IS-107, Reykjavik, Iceland.

PMID: 29239520
DOI: 10.1002/adma.201702463

Abstract

In a recent experimental paper, it was claimed that pronounced excitonic signatures are observed in optical response of Zn-based metal-organic frameworks (MOFs) at room temperature. Performing ab initio modelling, it is demonstrated that an alternative interpretation based on single-electron optical transitions between narrow π-bands in the system of aromatic rings of the ligand is far more plausible. Although these results do not rule the possibility of exciton formation in MOFs out completely, they show that extreme caution should be taken in attributing the features in photoabsorption spectra alone to excitons, and additional proof, such as data on long-distance energy transfer, is necessary.

Keywords: density functional theory; excitons; metal-organic frameworks.