Near-infrared emission of CaAl₆Ga₆O₁₉:Cr³⁺,Ln³⁺ (Ln = Yb, Nd, and Er) via energy transfer for c-Si solar cells

Abstract

In this study, we have reported broadband spectral conversion of UV/visible to near-infrared emission in the CaAl6Ga6O19:Cr3+,Ln3+ (Ln = Yb, Nd, and Er) materials for the c-Si solar cells via energy transfer.

Advances in Chromium‐Activated Phosphors for Near‐Infrared Light Sources

“…[ 59 ] This strategy of ET between Cr 3+ and rare earth ions to broaden the PL spectrum has been reported in many materials such as Ca 2 LuZr 2 Al 3 O 12 , Ca 2 LuHf 2 Al 3 O 12 , Gd 3 Sc 1.5 Al 0.5 Ga 3 O 12 , Gd 3 Sc 2 Ga 3 O 12 , Ca 3 Y 2 Ge 3 O 12 , Ca 2 MgWO 6 , LiIn 2 SbO 6 , LiScP 2 O 7 , YAl 3 (BO 3 ) 4 , Gd 2 GaSbO 7 , La 3 Ga 5.5 Nb 0.5 O 14 , CaAl 6 Ga 6 O 19 , Lu 0.2 Sc 0.8 BO 3 , etc. [ 14,28,70,107,108,193,245,247,296–301 ] Notably, although the ET between Cr 3+ and other luminescence centers can broaden the emission spectrum, it is often accompanied with the decrease in the luminescence intensity of sensitizer ions and difficult to maintain the color stability.…”

“…have been introduced into inorganic host materials to exhibit NIR luminescence. [ 7,11–16 ] However, rare earth ions Yb 3+ , Er 3+ , and Nd 3+ usually present narrowband emissions and the absorption is weak due to the parity forbidden f–f transition. [ 14 ] Although the parity allowed f–d transition of Eu 2+ ion enhances the absorption intensity, the emission peak is mainly located at visible light region.…”

“…[ 7,11–16 ] However, rare earth ions Yb 3+ , Er 3+ , and Nd 3+ usually present narrowband emissions and the absorption is weak due to the parity forbidden f–f transition. [ 14 ] Although the parity allowed f–d transition of Eu 2+ ion enhances the absorption intensity, the emission peak is mainly located at visible light region. Only a few Eu 2+ ‐doped phosphors have emission extending to far‐red region and it is difficult to achieve longer NIR emission wavelength.…”

Near-infrared Sr7NaGa(PO4)6:Cr3+,Ln3+ (Ln = Nd, Er, and Yb) phosphors with different energy transfer paths: photoluminescence enhancement and versatility

“…To better understand the energy transfer from the Cr 3+ to Ln 3+ ions, the average lifetime can be calculated using the equation as follows: 21,40 The lifetimes of the Cr 3+ ions in SNGP:0.15Cr 3+ ,Ln 3+ decrease continuously with increasing Ln 3+ -concentration, confirming that the energy is transferred from Cr 3+ to Ln 3+ ions. The energy transfer efficiency ( η ) was calculated using the following equation: 41 where τ and τ 0 are the lifetimes of Cr 3+ ions in the presence and absence of Ln 3+ ions, respectively. As shown in Fig.…”

Broadband NIR Garnet Phosphors with Improved Thermal Stability via Energy Transfer

“…Hence, enriching the longer-wavelength component (900–1100 nm) is of great importance. Codoping another activator that emits in the longer-wavelength region to utilize the energy transfer (ET) process is one of the common ways to solve the above problem, and it has been intensively studied in the Cr 3+ –Yb 3+ -codoped system, because the efficient emitter Yb 3+ can generate the NIR emission centered at 1000 nm. − On the other hand, the thermal stability of Cr 3+ will be limited by the structural properties of the host crystals due to its highly sensitive d–d transitions. − However, Yb 3+ has two unique energy levels that are separated by about 10 000 cm –1 , 2 F 7/2 and 2 F 5/2 , resulting in negligible multiphonon relaxation and thermally stable NIR emission. , Therefore, an improved thermal stability can also be achieved in Cr 3+ –Yb 3+ systems because of the occurrence of the ET process. ,, Therefore, codoping Yb 3+ will be an effective strategy to broaden the emission spectrum as well as improve the thermal stability simultaneously.…”