Excellent Upconversion Luminescence Obtained by Er³⁺ Self-Sensitization for Temperature Sensing in Deep Tissues and...

Area of Science:

• Materials Science
• Luminescence
• Nanotechnology

Background:

• High-efficiency upconversion (UC) materials are crucial for advanced applications.
• Materials emitting in the second near-infrared (NIR) biological window offer enhanced tissue penetration.
• Erbium (Er³⁺) doping is a common strategy for achieving UC luminescence.

Purpose of the Study:

• To investigate the upconversion luminescence properties of Er³⁺ in a CaSc₂O₄ matrix.
• To explore the potential of this material for optical thermometry and anticounterfeiting.
• To evaluate the performance of Er³⁺ self-sensitization under 1532 nm excitation.

Main Methods:

• Synthesis and characterization of CaSc₂O₄: Er³⁺ phosphor.
• Optical spectroscopy to analyze upconversion emissions (green, red, and NIR).
• Evaluation of thermometric sensitivity and variable color luminescence under dual-wavelength excitation (980 and 1532 nm).

Main Results:

• Strong green and red UC emission observed in CaSc₂O₄: Er³⁺.
• Efficient ⁴I_11/2 → ⁴I_15/2 NIR transition with a penetration depth of at least 6 mm in biological tissues.
• High sensitivity achieved in multipath optical thermometry.
• Variable color luminescence demonstrated under dual-wavelength excitation, suitable for anticounterfeiting.

Conclusions:

• CaSc₂O₄: Er³⁺ exhibits excellent upconversion properties, particularly under 1532 nm excitation within the biological window.
• The material shows significant promise for applications in sensitive optical thermometry and secure anticounterfeiting technologies.
• Er³⁺ self-sensitization in CaSc₂O₄ is an effective strategy for developing multifunctional luminescent materials.