Simultaneous Broadening and Enhancement of Cr³⁺Photoluminescence in LiIn₂SbO₆by Chemical Unit Cosubstitution: Night‐Vision and Near‐Infrared Spectroscopy Detection Applications

Abstract

Near‐infrared (NIR)‐emitting phosphor materials have been extensively developed for optoelectronic and biomedical applications. Although Cr3+‐activated phosphors have been widely reported, it is challenging to achieve ultra‐broad and tunable NIR emission. Here, a new ultra‐broadband NIR‐emitting LiIn2SbO6:Cr3+ phosphor with emission peak at 965 nm and a full‐width at half maximum of 217 nm is reported. Controllable emission tuning from 965 to 892 nm is achieved by chemical unit cosubstitution of [Zn2+–Zn2+] for [Li+–In3+], which can be ascribed to the upshift of 4T2g energy level due to the strengthened crystal field. Moreover, the emission is greatly enhanced, and the FWHM reaches 235 nm. The as‐prepared luminescent tunable NIR‐emitting phosphors have demonstrated the potential in night‐vision and NIR spectroscopy techniques. This work proves the feasibility of chemical unit cosubstitution strategy in emission tuning of Cr3+‐doped phosphors, which can stimulate further studies on the emission‐tunable NIR‐emitting phosphor materials.

Near‐infrared emitting metal halide materials: Luminescence design and applications

“…Some tuning approaches such as cation substitution/ cosubstitution, codoing, crystallinity improvement have been extensively explored in inorganic NIR-emitting phosphors. [205][206][207][208] However, related studies on NIR LMHs are still in the infancy stage. In this section, several feasible strategies toward improving luminescence and optoelectronic properties of NIR LMHs have been summarized, including bandgap engineering, self-trapping state engineering, chemical composition modification, energy transfer, and other auxiliary strategies such as improvement of synthesis scheme and postprocessing (Figure 6).…”

Broadband near-infrared luminescence in a cubic pyrophosphate Al0.5Ta0.5P2O7:Cr3+ phosphor for multi-functional applications

“…Generally, rare earth ions Eu 2+ and several transition metal ions (Cr 3+ , Ni 2+ , and Mn 2+ ) are preferred to be selected as activators for broadband NIR materials. 1,[23][24][25][26][27][28][29][30][31] Particularly, Cr 3+ when introduced into a weak octahedral crystal field exhibits broadband excitation in the blue light region and tunable NIR emission depending on crystal field strength, making it an ideal activator to convert blue light from a commercial InGaN LED into broadband NIR light. [32][33][34][35][36][37][38][39] Therefore, finding a suitable host for Cr 3+ is the main challenge for the designing of broadband NIR phosphors.…”

Sharp-Line Near-Infrared Emission from Tetrahedron-Occupied Ni2+ in Ca2GeO4

“…Near-infrared (NIR) emitting materials have gained enormous interest and exhibited potential applications in multiple fields like bio-imaging, food quality control, security camera, plant growth, and photovoltaics. , Various 3 d transition metals, such as Cr 3+ , Mn 2+ , Mn 5+ , Fe 3+ , Ni 2+ , and Cu 2+ , are commonly used as a luminescent center in inorganic NIR phosphors. − In this series, Cr and Ni have been extensively studied because of their promising luminescence properties. Cr 3+ is widely investigated as an efficient luminescent center, which exhibits a broadband NIR-I (700–950 nm) emission when it is substituted into the octahedral site with low crystal-field strength. − However, the NIR spectral region above 1000 nm could be only covered by the emission tail of Cr 3+ -activated phosphors with very low emission intensity. Thus, developing phosphors with a longer emission peak beyond 1000 nm for spectroscopic analysis, bio-imaging, and optical communication applications is urgently needed but rarely reported.…”