Luminescence decay characteristics of CdS quantum dots doped with europium ions

Abstract

In the present paper, we present an analysis of the luminescence decays for colloidal quantum dots (QDs) with interfaces doped with Eu3+ ions of the corresponding thenoyltrifluoroacetone complexes. The luminescence decay features related to concentration and temperature effects are considered. The Stern-Volmer plots obtained at 300 and 77 K for the trap state luminescence of CdS:Eu3+ QDs show that the QD luminescence quenching is of a dynamic character with the Stern-Volmer constant being Kdyn=3.7⋅105 M−1. Non-radiative excitation energy transfer from the trap state luminescence centers in CdS quantum dots to Eu3+ ions is observed. In addition, the value of the quenching rate kdyn=2.37⋅1013s−1⋅M−1 indicates that the energy transfer process has a non-diffusive nature. This conclusion is supported by the effective quenching in a frozen solution at 77 K where there is no diffusion. For CdS/TGA QDs doped with europium ions, we observe a significant increase in the luminescence lifetime (from 190 μs to 346 μs) for the band peaked at about 615 nm as compared to the free Eu:TTA complex. We conclude that Eu3+ ions are incorporated into the QD interfaces.