Issue 8, 2022

Local environment rigidity and the evolution of optical properties in the green-emitting phosphor Ba1−xSrxScO2F:Eu2+

Abstract

Developing chemically and thermally stable, highly efficient green-emitting inorganic phosphors is a significant challenge in solid-state lighting. One accessible pathway for achieving green emission is by forming a solid solution with superior blue-emitting materials. In this work, we demonstrate that the cyan-emission (λem = 481 nm) of the BaScO2F:Eu2+ perovskite can be red-shifted by forming a solid solution following (Ba1−xSrx)0.98Eu0.02ScO2F (x = 0, 0.075, 0.15, 0.25, 0.33, 0.40). Although green emission is achieved (λem = 516 nm) as desired, the thermal quenching (TQ) resistance is reduced, and the photoluminescence quantum yield (PLQY) drops by 65%. Computation reveals the source of these changes. Surprisingly, a basic density functional theory analysis shows the gradual SrBa substitution has negligible effects on the band gap (Eg) energy, suggesting the activation energy barrier for the thermal ionization quenching remains unchanged, while the nearly constant Debye temperature indicates no loss of average structural rigidity to explain the decrease in the PLQY. Instead, temperature-dependent ab initio molecular dynamics (AIMD) simulations show that gradual changes of the Eu2+ ion's local coordination environment rigidity are responsible for the drop in the observed TQ and PLQY. These results express the need to computationally analyze the local rare-earth environment as a function of temperature to understand the fundamental origin of optical properties in new inorganic phosphors.

Graphical abstract: Local environment rigidity and the evolution of optical properties in the green-emitting phosphor Ba1−xSrxScO2F:Eu2+

Supplementary files

Article information

Article type
Paper
Submitted
09 11 2021
Accepted
28 1 2022
First published
31 1 2022

J. Mater. Chem. C, 2022,10, 2955-2964

Author version available

Local environment rigidity and the evolution of optical properties in the green-emitting phosphor Ba1−xSrxScO2F:Eu2+

S. Hariyani, M. Amachraa, M. Khan, S. P. Ong and J. Brgoch, J. Mater. Chem. C, 2022, 10, 2955 DOI: 10.1039/D1TC05411B

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