Achieving High Quantum Efficiency Broadband NIR Mg₄Ta₂O₉:Cr³⁺ Phosphor Through Lithium‐Ion Compensation

Abstract

Ultra‐efficient broadband near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are urgently needed to improve the detection sensitivity and spatial resolution of current smart NIR spectroscopy‐based techniques. Nonetheless, the performance of NIR pc‐LED has severely limited owing to the external quantum efficiency (EQE) bottleneck of NIR light‐emitting materials. Herein, a blue LED excitable Cr3+‐doped tetramagnesium ditantalate (Mg4Ta2O9, MT) phosphor is advantageously modified through lithium ion as a key efficient broadband NIR emitter to achieve high optical output power of the NIR light source. The emission spectrum encompasses the 700–1300 nm electromagnetic spectrum of first biological window (λmax = 842 nm) with a full‐width at half‐maximum (FWHM) of ≈2280 cm−1 (≈167 nm), and achieves a record EQE of 61.25% detected at 450 nm excitation through Li‐ion compensation. A prototype NIR pc‐LED is fabricated with MT:Cr3+, Li+ to evaluate its potential practical application, which reveals an NIR output power of 53.22 mW at a driving current of 100 mA, and a photoelectric conversion efficiency of 25.09% at 10 mA. This work provides an ultra‐efficient broadband NIR luminescent material, which shows great promise in practical applications and presents a novel option for the next‐generation high‐power compact NIR light sources.

Enhanced photoluminescence of a HF free novel NIR phosphor of K2ZnF4:Cr3+by lithium ion doping

“…The charge compensation mechanism by Li + can be described as Cr 3+ + Li + → 2Zn 2+ , which means that one Li + ion and one Cr 3+ ion co-replace two Zn 2+ ions. 21,22 In order to study the effect of Li + additive on the luminescence performance of K 2 ZnF 4 :0.04Cr 3+ , y Li + ( y = 0–0.06), we analyzed and tested the emission characteristics of Cr 3+ in the absence or presence of alkaline metal ions under excitation at 465 nm, as presented in Fig. 5(c).…”

Efficient and ultra-broadband Cr3+/Ni2+ co-doped phosphors for light-emitting diodes with spectral output over NIR-I and NIR-II regions

“…A large number of Cr 3+ -activated NIR phosphors have been reported in the last five years. 8,[10][11][12][13][14][15][16][17][18] Some of them exhibit high luminescence efficiency and good thermal stability, but normally have short emission wavelengths and narrow bandwidth. For spectroscopic analysis, NIR light sources are required to provide as broad spectral output as possible so that more substances can be detected or recognized.…”

Highly efficient and thermally stable broadband near-infrared emitting garnet Ca3Sc2Ge3O12:Cr3+,Ce3+ phosphors for multiple pc-LED applications

“…1–8 Traditional infrared light sources such as halogen tungsten filament lamps and continuous lasers have the disadvantages of large volume and poor efficiency, which cannot meet the requirements of commercial applications. 9 Inspired by white light-emitting diode (LED) technology, NIR emitting phosphor-converted LEDs (NIR pc-LEDs) have been extensively studied in recent years as they can be easily integrated into smartphones and wearable electronic devices for multifunctional applications. 10,11 As one of the essential components of NIR pc-LEDs, the NIR phosphor plays a vital role in the performance of the device.…”