Strategies for Designing Antithermal-Quenching Red Phosphors

Abstract

Nowadays, red phosphor plays a key role in improving the lighting quality and color rendering index of phosphor-converted white light emitting diodes (w-LEDs). However, the development of thermally stable and highly efficient red phosphor is still a pivotal challenge. Herein, a new strategy to design antithermal-quenching red emission in Eu³⁺, Mn⁴⁺-codoped phosphors is proposed. The photoluminescence intensity of Mg₃Y_{2(1- y )}Ge₃O₁₂:yEu³⁺, Mn⁴⁺ (0 ≤ y ≤ 1) phosphors continuously enhances with rising temperature from 298 to 523 K based on Eu³⁺ → Mn⁴⁺ energy transfer. For Mg₃Eu₂Ge₃O₁₂:Mn⁴⁺ sample, the integrated intensity at 523 K remarkably reaches 120% of that at 298 K. Interestingly, through codoping Eu³⁺ and Mn⁴⁺ in Mg₃Y₂Ge₃O₁₂, the photoluminescence color is controllably tuned from orangish-red (610 nm) to deep-red (660 nm) light by changing Eu³⁺ concentration. The fabricated w-LEDs exhibit superior warm white light with low corrected color temperature (CCT = 4848 K) and high color rendering index (R _a = 96.2), indicating the promising red component for w-LED applications. Based on the abnormal increase in antistokes peaks of Mn⁴⁺ with temperatures, Mg₃Eu₂Ge₃O₁₂:Mn⁴⁺ phosphor also presents a potential application in optical thermometry sensors. This work initiates a new insight to construct thermally stable and spectra-tunable red phosphors for various optical applications.

Keywords: Eu3+ → Mn4+ energy transfer; antithermal quenching; color adjustment; red phosphor; white light emitting diodes (w‐LEDs).