Harnessing the inherent photoluminescence of Ba2MgTeO6 double perovskite phosphor for visible to near infrared pc-LED applications

Abstract

Phosphor-converted LEDs (pc-LEDs) emitting in the visible region based on undoped tellurate double perovskites have not been explored till now. A cyan-emitting pc-LED is fabricated using the host Ba₂MgTeO₆ double perovskite for the first time. The as-fabricated cyan LED emits light in the visible region with the maximum emission at 484 nm. The obtained CIE coordinates of (0.26, 0.37) ensure a cyan light, and LED exhibits superior color stability even at higher input drive current. An attempt to develop a white emitting phosphor was done by substituting Eu³⁺ ions into the Ba₂MgTeO₆ matrix. Followed by this, a phosphor converted LED emitting in the bluish white region was fabricated by combining near UV chip and BMTO: 0.02 Eu³⁺ phosphor. Further, an inherent near-infrared (NIR) luminescence in Ba₂MgTeO₆ is also discovered and it originates from the ³T_1u, ³A_1u – ¹A_1g electronic transitions within the Te⁴⁺ ions. Upon 367 nm excitation, Ba₂MgTeO₆ exhibits strong broadband NIR emission, which spans from 780 nm to 1150 nm with a maximum emission at 889 nm and full width at half maximum (FWHM) of about 115 nm. Finally, an efficient pc-LED emitting in the NIR region is fabricated using the intrinsic near-infrared luminescence observed in the Ba₂MgTeO₆ phosphor. The pc-LED covering the near infrared region can be potentially used for various applications, including plant cultivation, biosensors, night vision cameras, etc.