Electrical engineering

Physics

Infrared

Organic chemistry

Dopant

Quantum efficiency

Analytical Chemistry (journal)

Optics

Phosphor

Absorption (acoustics)

Photon upconversion

Quenching (fluorescence)

Engineering

Luminescence

Composite material

Chemistry

Materials science

Emission intensity

Photoluminescence

Chromatography

Optoelectronics

Doping

Excitation

Fluorescence

Chemistry of Materials

Trivalent chromium ion-doped near-infrared (NIR) phosphors have been widely studied due to their tunable emission wavelengths and broad applications. High Cr3+ concentration can improve absorption efficiency but generally results in low emission intensity due to the concentration quenching effect. Herein, we report a series of efficient NIR phosphors with suppressed concentration quenching, Sr9M1–x(PO4)7:xCr3+ (M = Ga, Sc, In, and Lu), showing a broadband NIR emission ranging from 700 to 1100 nm peaking at 850 nm upon the 485 nm light excitation. The emission peak position is almost independent of the type of M ion and the Cr3+ dopant content, and the type of M ion has little influence on the luminescence thermal quenching, indicating that [MO6] octahedra are rigid enough to keep octahedral volumes and average M3+–O2– distances nearly constant owing to the formation of the framework structure on Cr3+ substitution. The NIR emission intensities monotonously increase with the Cr3+ content increasing from 0 to 80% with suppressed concentration quenching, the intensity of Sr9Cr(PO4)7 still maintains 84.23% of Sr9Ga0.2(PO4)7:0.8Cr3+ phosphor, and the thermal quenching behavior is slightly dependent on x; these effects can be attributed to the suppressed energy transfer due to the structural confinement effect. The optimal sample, Sr9Ga0.2(PO4)7:0.8Cr3+, has an internal/external quantum efficiency of 66.3%/29.9%. Finally, we fabricate a NIR phosphor-conversion light-emitting diode and demonstrate its applications in nondestructive examination and medical fields.

Structural Confinement for Cr<sup>3+</sup> Activators toward Efficient Near-Infrared Phosphors with Suppressed Concentration Quenching

Structural Confinement for Cr3+ Activators toward Efficient Near-Infrared Phosphors with Suppressed Concentration Quenching

Structural Confinement for Cr³⁺ Activators toward Efficient Near-Infrared Phosphors with Suppressed Concentration Quenching