Avoiding concentration quenching and self-absorption in Cs4EuX6 (X = Br, I) by Sm2+ doping

Casper van Aarle; Karl W Krämer; Pieter Dorenbos

doi:10.1039/d2tc05311j

Avoiding concentration quenching and self-absorption in Cs₄EuX₆ (X = Br, I) by Sm²⁺ doping

J Mater Chem C Mater. 2023 Jan 27;11(6):2336-2344. doi: 10.1039/d2tc05311j. eCollection 2023 Feb 9.

Authors

Casper van Aarle¹, Karl W Krämer², Pieter Dorenbos¹

Affiliations

¹ Faculty of Applied Sciences, Delft University of Technology Mekelweg 15 Delft The Netherlands c.vanaarle@tudelft.nl.
² Department of Chemistry and Biochemistry, University of Bern Freiestrasse 3 Bern Switzerland.

Abstract

The benefits of doping Cs₄EuBr₆ and Cs₄EuI₆ with Sm²⁺ are studied for near-infrared scintillator applications. It is shown that undoped Cs₄EuI₆ suffers from a high probability of self-absorption, which is almost completely absent in Cs₄EuI₆:2% Sm. Sm²⁺ doping is also used to gain insight in the migration rate of Eu²⁺ excitations in Cs₄EuBr₆ and Cs₄EuI₆, which shows that concentration quenching is weak, but still significant in the undoped compounds. Both self-absorption and concentration quenching are linked to the spectral overlap of the Eu²⁺ excitation and emission spectra which were studied between 10 K and 300 K. The scintillation characteristics of Cs₄EuI₆:2% Sm is compared to that of the undoped samples. An improvement of energy resolution from 11% to 7.5% is found upon doping Cs₄EuI₆ with 2% Sm and the scintillation decay time shortens from 4.8 s to 3.5 s in samples of around 3 mm in size.