Broadband downconversion based infrared quantum cutting by cooperative energy transfer from Eu2+ to Yb3+ in glasses

Abstract

Near-infrared quantum cutting involving the emission of near-infrared photons by downconversion cooperative energy transfer from Eu2+ to Yb3+ in borate glasses was reported. Electron spin resonance spectra and absorption spectra were measured to prove the existence of Eu2+ in borate glasses. Excitation, emission, and fluorescence decay measurements were performed to examine the occurrence of cooperative energy transfer from Eu2+ to Yb3+ ions. Yb3+ concentration dependent quantum efficiency was calculated and the maximum efficiency approaches 164.19%.

Infrared cascade and cooperative multicolor upconversion emissions in Y_8V_2O_17:Eu:Yb nanophosphors

“…By taking the ratio between the estimated and experimental (~401 ± 1 µs) lifetimes, the QE of the sample was estimated to be ~13%. This QE is comparable to the efficiency of YVO 4 As seen in Fig. 4, when Yb 3+ ions coexist with Eu 3+ ions, all peaks present in the singly doped Eu sample spectrum appear, together with a broad NIR band centered at 980 nm.…”

“…Recently, the unification of lanthanide spectroscopy with nanotechnology expanded their applications from display devices and sensors to the biomedical field. Among lanthanide elements Europium (Eu) is considered as one of the best known red emitting lanthanide ions having quantum efficiency (QE) up to ~90% in the red region [4] and for this reason, the Eu 3+ ion is a well-known activator, widely used as red phosphor in television screens and fluorescent lamps etc [5]. The use of other lanthanide ions such as Er, Ho, Sm, Gd and Pr as source of red color is limited by their small absorption cross-section and consequently, low QE.…”

“…The solution color change from yellow to light green suggests the vanadium valence reduction from + 5 to + 3. 10 ml of NH 4 OH was added soon after the addition of 5 ml of ethylene glycol under constant stirring. The white precipitate obtained was washed three times with ethanol and distilled water, and was then isolated by centrifugation at 5000 rpm for 15 minutes in ethanol solution.…”

Highly efficient near-infrared quantum cutting in Ce3+/Yb3+ co-doped chalcohalide glasses

“…Compared to the single doped samples, the codoped sample shows very strong NIR emissions centered at ~ 980 nm-1020 nm due to the 2 F 5/2 → 2 F 7/2 transitions of Yb 3+ [5][6][7], but the visible emission is much reduced, implying that there exists an efficient ET from Ce 3+ to Yb 3+ . From the excitation spectra monitored at the 988 nm emission of Yb 3+ (dashed line in Fig.2) it is clear that co-doping of Ce 3+ (G2) leads to a much broader and more intense excitation band with the maximum wavelength shifted to the blue region.…”

“…Downconversions including downshifting and quantum cutting (QC), are important methods of modifying the solar photon flux spectrum. Many efforts have been made to develop NIR QC phosphors or glasses co-doped with Yb 3+ and other rare-earth ions (RE 3+ ) [5][6][7]. The Yb 3+ is suitable as an acceptor and emitter because luminescence quantum efficiency of Yb 3+ is close to 100% and most importantly, the transition energy from the only excited level to the ground state of Yb 3+ : 2 F 5/2 → 2 F 7/2 (~1.2 eV) is roughly in accordance with the band gap of Si (~1.1 eV).…”