Role of electron transfer in Ce3+ sensitized Yb3+ luminescence in borate glass

Abstract

In a Ce 3þ-Yb 3þ system, two mechanisms are proposed so far namely, the quantum cutting mechanism and the electron transfer mechanism explaining Yb 3þ infrared luminescence under Ce 3þ excitation. Among them, the quantum cutting mechanism, where one Ce 3þ photon (ultraviolet/blue) gives rise to two Yb 3þ photons (near infrared) is widely sought for because of its huge potential in enhancing the solar cell efficiency. In present study on Ce 3þ-Yb 3þ codoped borate glasses, Ce 3þ sensitized Yb 3þ luminescence at $1 lm have been observed on Ce 3þ 5d state excitation. However, the intensity of sensitized Yb 3þ luminescence is found to be very weak compared to the strong quenching occurred in Ce 3þ luminescence in Yb 3þ codoped glasses. Moreover, the absolute luminescence quantum yield also showed a decreasing trend with Yb 3þ codoping in the glasses. The overall behavior of the luminescence properties and the quantum yield is strongly contradicting with the quantum cutting phenomenon. The results are attributed to the energetically favorable electron transfer interactions followed by Ce 3þ-Yb 3þ Ce 4þ-Yb 2þ intervalence charge transfer and successfully explained using the absolute electron binding energies of dopant ions in the studied borate glass. Finally, an attempt has been presented to generalize the electron transfer mechanism among opposite oxidation/reduction property dopant ions using the vacuum referred electron binding energy (VRBE) scheme for lanthanide series.

Significance of host׳s intrinsic absorption band tailing on Ce3+ luminescence quantum yield in borate glass

“…In case of Ce 3 þ doped glass, the spectrum shows additional intense absorption bands in the 200-380 nm wavelength range due to the 4f-5d j absorption transitions of Ce 3 þ ions. The Ce 3 þ absorption exhibits five distinct splitting characteristic to five-fold non-degeneracy of excited 5d orbitals as represented in the host referred electron binding energy level diagram of Ce 3 þ in the present borate glass (inset) [10].…”

“…Borate glasses with base composition of 55 B 2 O 3 -20 CaO -10 Al 2 O 3 -15 La 2 O 3 in mol% were synthesized by high temperature melt quenching method [10]. The doped glasses were obtained by substituting a fraction of La 2 O 3 contents with an equivalent amount of the dopant contents.…”

“…Note that the Ce 3 þ 5d 1 state is close to the conduction band and upper 5d j states are inside the conduction band in present borate glass [10,19]. Therefore, to restrict the influence of thermal ionization of excitation population to the conduction band, the excitation was carried at the Ce 3 þ 5d 1 state using a 372 nm laser diode.…”

Tuning the Structure and Properties of Lanthanoid Coordination Polymers with an Asymmetric Anilato Ligand

“…The main difference is the presence of a third peak at the near-infrared in compound 4, labelled as PYb. This peak is the well-known signature of the Yb(III) ion, and it corresponds to the transition 2 F5/2 → 2 F7/2 [45]. Since 2 F5/2 is the only excited state of the Yb(III), no more peaks can be ascribed to this ion.…”

Spectral Properties and Energy Transfer between Ce3+ and Yb3+ in the Ca3Sc2Si3O12 Host: Is It an Electron Transfer Mechanism?

“…Thus, as long as the 5d(1) level lies above the Yb 2+ ground state energy in the vacuum referred binding energy (VRBE) diagram, the transfer process 3 is energetically possible. 6,7 Notice that in this case the electron transfer involves two spin doublet initial states and two spin singlet final states.…”