Intense red upconversion emission of Yb/Tm/Ho triply-doped tellurite glasses

Recent progress in lanthanide-doped luminescent glasses for solid-state lighting applications-a review

Nowadays, solid-state white light-emitting diodes (wLEDs) have attracted remarkable attention for applications in general lighting, displays and numerous electronical devices due to their eminent efficiency, longer lifetime and higher mechanical durability compared to traditional incandescent and fluorescent lights. In current commercial wLEDs, a combination of Y₃Al₅O₁₂:Ce³⁺yellow phosphor with blue LED chip and epoxy resin is generally used to generate white light. However, there are some considerable frailties mostly originated from phosphor and resin such as, degradation upon heat, and moisture, inhomogeneous spectral distribution, and poor color rendering capability. Therefore, phosphor embedded glass-ceramics have been developed as a promising way to obtain durable solid-state lighting devices. However, in these methods, there is a greater risk of reactions between the phosphor material and the glass host. At this point, lanthanide-doped luminescent glasses have drawn great attention as a new generation phosphor and/or epoxy free white-light-emitting source owing to their favorable properties including high thermal and chemical stability, high transparency, and easy manufacturing process. This review article aims to comprehensively summarize the recent progress in singly (i.e., Dy³⁺, Eu²⁺), doubly (i.e., Dy³⁺/Eu³⁺, Dy³⁺/Tm³⁺, Dy³⁺/Ce³⁺, Ce³⁺/Sm³⁺, Ce³⁺/Tb³⁺) and triply (i.e., Ce³⁺/Tb³⁺/Mn²⁺, Eu³⁺/Tb³⁺/Tm³⁺, Ce³⁺/Tb³⁺/Eu³⁺, Tm³⁺/Tb³⁺/Sm³⁺, Ce³⁺/Dy³⁺/Eu³⁺, Ho³⁺/Tm³⁺/Yb³⁺, Er³⁺/Tm³⁺/Yb³⁺) lanthanide-doped glasses for solid-state lighting applications through down-shifting and up-conversion emissions. Theoretical background including energy transfer mechanisms, glass synthesis methods, radiative and colorimetric properties are given in details. Finally, various effective strategies are highlighted that minimize the critical challenges associated with lanthanides-such as providing energy transfer from quantum dots or nanoparticles to lanthanides, and doping lanthanides in low phonon energy glass-to improve the white light emission of luminescent glasses and broaden their application areas.

A novel holmium–mercury complex: Structure, green photoluminescence, energy transfer mechanism and semiconducting properties

The complex (Ho(IA)3(H3O)(H2O)) n(0.5 nHg2I6) (HIA = isonicotinic acid) has been synthesized via a hydrothermal reaction and has a one-dimensional (1D) chain-like structure. It has an emission band in the green region of 542 nm, which could originate from the 5 S2 → 5 I8 transition of the Ho3+ ion. The compound possesses Commission Internationale de I’Éclairage chromaticity coordinates of (0.2065, 0.4969) and has a wide optical band gap of 2.32 eV, as found by solid-state UV-Vis diffuse reflectance measurements.

Intense 2.7 µm emission of Er3+-doped water-free fluorotellurite glasses

By physical and chemical dehydration techniques, a group of Er3+-doped water-free fluorotellurite glasses with a composition of 60TeO2-30ZnF2-10NaF(TZNF60,mol%)+x Er2O3(wt%,x=0~1.5) were fabricated. Under 978 nm excitation, the 4I(11/2)→4I(13/2) emission of Er3+ ions in TZNF60-glass was investigated: τ(f) is of 1.07~1.93 ms and emission bandwidth is about 163 nm at 2.71 µm, which benefits from the absence of OH groups and the decreased phonon energy with the addition of fluorides. In contrast, 1.25Er-TZNF60 glass is proposed to be a promising material for mid-infrared fiber lasers at around 2.7 µm.