Blue InGaN chip-pumped short-wave infrared (SWIR) emitters
have
aroused tremendous attention and shown emerging applications in diverse
fields such as healthcare, retail, and agriculture. However, discovering
blue light-emitting diode (LED)-pumped SWIR phosphors with a central
emission wavelength over 1000 nm remains a significant challenge.
Herein, we demonstrate the efficient broadband SWIR luminescence of
Ni2+ by simultaneously incorporating Cr3+ and
Ni2+ ions into the MgGa2O4 lattice,
with Cr3+ as the sensitizer and Ni2+ as the
emitter. Because of the strong blue light absorption of Cr3+ and high energy transfer efficiency to Ni2+, the obtained
MgGa2O4:Cr3+, Ni2+ phosphors
show intense SWIR luminescence with a peak wavelength at 1260 nm and
a full width at half maximum (FWHM) of 222 nm under the excitation
of blue light. The optimized SWIR phosphor presents an ultra-high
SWIR photoluminescence quantum efficiency of 96.5% and outstanding
luminescence thermal stability (67.9%@150 °C). A SWIR light source
has been fabricated through a combination of the prepared MgGa2O4:Cr3+, Ni2+ phosphor and
a commercial 450 nm blue LED chip, delivering a maximum SWIR radiant
power of 14.9 mW at 150 mA input current. This work not only demonstrates
the feasibility of developing broadband high-power SWIR emitters using
converter technology but also presents new insights into the importance
of SWIR technology.
Short-wave infrared (SWIR) light sources featuring large spectral bandwidth and high luminescence efficiency have found wide applications in the fields of night vision, non-destructive detection, covert information identification, and biomedical...
Infrared-emitting
phosphor-converted light-emitting diodes (LEDs)
are desirable light sources for a very wide range of applications
such as spectroscopy analysis, nondestructive monitoring, covert information
identification, and night-vision surveillance. The most important
aspect of infrared emitters for spectroscopy is to cover the widest
possible wavelength range of emitted light. However, developing ultrabroad-band
infrared emitters based on converter technology is still a challenging
task due to the lack of suitable phosphor materials that emit in a
wide wavelength range upon excitation from blue-emitting chips. Herein,
this work demonstrates Cr3+-activated Mg2SiO4 infrared phosphors with a super wide infrared spectral range
of 600 to 1400 nm and high internal quantum yield up to 80.4% upon
460 nm excitation. Site-selective occupancy of Cr3+ emitters
in two different Mg sites in the Mg2SiO4 lattice
results in two distinct broad emission bands peaking at 760 and 970
nm, both of which contribute to the ultrabroad-band infrared luminescence
with a full width at half maximum (FWHM) of 419 nm. This is by far
the broadest infrared emission to the best of our knowledge. On this
basis, an ultrabroad-band infrared LED prototype has been fabricated
by the combination of the Mg2SiO4:Cr3+ phosphor with a blue LED chip, which shows great potential for imaging
and sensing applications. This work demonstrates that site-selective
occupancy control of Cr ions is an effective strategy for developing
ultrabroad-band Cr3+-doped phosphors.
Luminescence Boltzmann thermometry is becoming one of the most trustworthy methods for locally measuring temperature in noncontact mode. In this work, we report a comprehensive spectroscopic study of the Cr3+...
Trivalent europium (Eu3+) doped phosphors usually radiate orange or red light owing to distinct transitions from the 5D0 excited level to the ground states of 7F1 and 7F2. However, Eu3+ activated phosphors with a dominant deep‐red emission due to 5D0→7F4 transition are relatively rare. In this work, the synthesis and photoluminescence properties of Ca3Al2Ge3O12:Eu3+ deep‐red phosphor with an intense 5D0→7F4 transition are reported. Irradiating this new garnet phosphor with 394 nm near‐ultraviolet light generates a dominant deep‐red emission band centered at 707 nm. The phosphor has a high internal quantum efficiency of 98.4% and excellent luminescence thermal stability, maintaining 78.8% of the room temperature emission intensity at 150 °C. Based on the unique spectral feature of this new compound, a phosphor‐converted deep‐red LED prototype device is fabricated, producing an output power of 27.3 mW with a photoelectric conversion efficiency of 4.0% at 200 mA. Plant growth experiments are also conducted to demonstrate the obvious positive effects of the fabricated deep‐red LED on plant growth, further indicating that the as‐prepared Ca3Al2Ge3O12:Eu3+ deep‐red phosphor can act as a promising luminescence converter for plant growth LED bulbs.
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