Broadband Near‐Infrared Down‐Shifting by Yb–O Charge‐Transfer Band in Yb³⁺ Singly Doped Tellurite Glasses

Abstract

Yb3+ singly doped tellurite as‐prepared glasses and glass ceramics were synthesized by high‐temperature melt‐quenching method. The excitation and emission spectra have shown that there is an efficient near‐infrared (NIR) down‐shifting due to the sensitization of a novel Yb3+–O2− charge‐transfer (CT) band. The CT band in the present host is located at around 320 nm at room temperature, which is much lower than that in other oxide hosts reported before. The possible energy‐transfer mechanism from the Yb3+–O2− CT band to the 2F5/2 multiplet of Yb3+ ions is discussed in detail. The concentration quenching is not observed even when the Yb3+‐doped concentration is increased up to 40 mol%. The excitation of this strong broad CT band causes intense NIR emission of Yb3+:2F5/2→2F7/2 from 920 to 1120 nm, making the tellurite glasses suitable for efficient photovoltaic (PV) application as a spectral conversion material for the crystalline Si (c‐Si) solar cells.

An Efficient Dual‐Mode Solar Spectral Modification for c‐Si Solar Cells in Tm3+/Yb3+ Codoped Tellurite Glasses

“…It should be noted that there is a broad excitation band ranging from 240 to 400 nm and centered at about 320 nm by monitoring the Yb 3+ : 2 F 5/2 → 2 F 7/2 transition at 976 and 1020 nm in Tm 3+ /Yb 3+ codoped samples. This broad band, which has also been observed in the singly doped tellurite glass, is assigned to Yb 3+ ‐O 2− charge‐transfer band, as reported in our previous work …”

“…The studied tellurite glasses in this work were with the composition of 75TeO 2 –20ZnO–5Na 2 O‐0.5Tm 3+ – x Yb 3+ ( x = 0, 0.5, 2, 3, 4, 8), which were referred as TZN:Tm 0.5 Yb x ( x = 0, 0.5, 2, 3, 4, 8) hereafter. The preparation of the samples was similar with our previous work . Stoichiometric amount of TeO 2 (99.99%), ZnO (99.99%), Na 2 CO 3 (99.99%), Yb 2 O 3 (99.99%), and Tm 2 O 3 (99.99%) were ground homogeneously in an agate mortar and melted at 950°C for 30 min in a corundum crucible in the air.…”

Response of Various Yb3+-Doped Oxide Glasses to Different Radiation Treatments

“…Yb 3+ charge transfer (CT) -related absorption bands are a potential source for absorption bands [51,52], but, here, they cannot be resolved from the absorption spectra in Figure 2. Any such band would be expected to occur in the deep UV for all glasses [53][54][55]. Furthermore, any changes to the CT process itself would be a result of changes in the Yb 3+ local environment, such as the defects of interest.…”

Sandwich-like transparent ceramic demonstrates ultraviolet and visible broadband downconversion luminescence

“…23,40,41 Downconversion caused by the Yb-O charge transfer band has been observed in many host materials. 42,43 However, it is not seen in this work, because the Yb-O charge transfer band decays quickly in the bulk Y 2 O 3 host (lifetime $ 72 ns) and quenches easily with increasing temperature (quenching temperature $ 130 K). 28 In the PLE spectra of the sandwich-like Ce, Yb:YLZO ceramic, excitation bands in both the UV and Vis range (250-650 nm) have been detected (Fig.…”