Unraveling Luminescent Energy Transfer Pathways: Futuristic Approach of Miniature Shortwave Infrared Light-Emitting Diode Design

Abstract

Phosphor-converted shortwave infrared phosphor light-emitting diodes (pc-SWIR LEDs, 900−1700 nm) are promising next-generation portable light sources for spectroscopy, security, optical communication, and medical applications. A typical design strategy involves energy transfer from Cr 3+ to Ni 2+ , and thus, energy transfer from Cr 3+ −Cr 3+ pairs to Ni 2+ ions is important but challenging. Here, we report a Sr 1−x La x Al 5.92 Cr 0.08 Ga 6−x O 19 :xNi 2+ (x = 0−0.09) series for the SWIR emissions range of 900−1600 nm due to an energy transfer from Cr 3+ and Cr 3+ −Cr 3+ pair to Ni 2+ . Short-range structural studies using electron paramagnetic resonance and magnetometry measurements reveal that Ni 2+ ions likely exist as isolated Ni 2+ ions and Cr 3+ −Ni 2+ pairs rather than forming Ni 2+ −Ni 2+ pairs. The fabricated prototype SWIR pc-LED delivers a radiant flux of 12.43 mW under a 350 mA driving current. This work provides insights into the codopant strategy for energy transfer and the design of promising next-generation SWIR phosphors.

Understanding enormous redshifts in highly concentrated Mn2+ phosphors

“…In recent publications redshifted NIR emission was also reported for exchange coupled Cr 3+ dimers with shifts of about 1000 cm −1 from the isolated 2 E → 4 A 2 Cr 3+ emission around 700 nm. 63,64 These shifts are in line with redshifts expected for exchange coupled Cr 3+ pairs. Exchange interaction in dimers is known to be stronger for Cr 3+ than for Mn 2+ which results in higher magnetic transition temperatures ( e.g.…”

Boosting broadband short-wave infrared emission to achieve near-unity quantum efficiency via bridging Cr3+–Ni2+ in spinel solid-solutions towards light-emitting diode applications

“…To address this issue, a strategy of constructing an energy bridge has been proposed, i.e., by incorporating Cr 3+ ions that strongly absorb blue light and transfer energy efficiently to Ni 2+ , thus amplifying the SWIR emission intensity. Guided by this method, some blue light excitable and broadband SWIR emitting phosphors, such as MgO:Cr 3+ , Ni 2+ (83%@423 K, IQE = 92.7%), 32 LiMgPO 4 :Cr 3+ ,Ni 2+ (42% @423 K, IQE = 5.2%), 33 Mg 2 SnO 4 :Cr 3+ ,Ni 2+ (20.9%@423 K, IQE = 48.5%), 34 Sr 0.98 La 0.02 Al 5.92 Cr 0.08 Ga 5.98 O 19 :Cr 3+ ,Ni 2+ (59% @450 K, IQE = 62%), 35 LaMgGa 11 O 19 :Cr 3+ ,Ni 2+ (66%@373 K, IQE = 70%), 36 Zn 1.492 Sn 0.5 Ga 0.86 O 4 :Cr 3+ ,Ni 2+ (18%@403 K, IQE = 48%), 37 ZnGa 2 O 4 :Cr 3+ ,Ni 2+ (28.7%@400 K, IQE = 8.3%), 38 and MgGa 2 O 4 :Cr 3+ ,Ni 2+ (64.5%@423 K, IQE = 96.5%), 39 have been reported. Nevertheless, the purposeful design of Cr 3+ -Ni 2+ codoped broadband SWIR phosphors with high quantum efficiency and thermal stability for commercial use still remains an open question.…”

Ultrahigh Quantum Efficiency Near-Infrared-II Emission Achieved by Cr3+ Clusters to Ni2+ Energy Transfer

“…However, this intensity decrease was not accompanied by the broadening of the signal, as shown in Figure S5a, with a change in only the concentration of Cr 3+ . Therefore, all spin Hamiltonian (SH) parameter fittings were conducted for experimental data as shown in Figures S5c,d ) or SH fitting parameters, 39 suggesting that Ni 2+ substitutes at the octahedral Mg 2+ site with the same ionic valency, similar ionic radii, and suitable symmetric environment, reinforcing the nominal chemical formula. Temperaturedependent magnetic susceptibility (MS) is shown in Figure S7 and confirms the EPR results.…”