Towards highly efficient NIR II response up-conversion phosphor enabled by long lifetimes of Er.

The second near-infrared (NIR II) response photon up-conversion (UC) materials show great application prospects in the fields of biology and optical communication. However, it is still an enormous challenge to obtain efficient NIR II response materials. Herein, we develop a series of Er doped ternary sulfides phosphors with highly efficient UC emissions under 1532 nm irradiation.

Enhanced core-shell CeO:Er,Yb@WO heterojunction H generation by multiband emissions of Er ions.

The core-shell CeO:Er,Yb@WO heterojunction is successfully synthesized via the facile solvothermal method. The octahedral CeO:Er,Yb nanocrystal's core exhibits green (H, S → I), red (F → I) and NIR (I → I and I → I) emission under 980 nm laser diode excitation, and the multiband emissions are absorbed by the WO nanowire's shell, re-exciting its higher energy localized surface plasmon resonances (LSPR). With the excitation of 980 nm, the photocatalytic property of CeO:Er,Yb@WO for hydrogen (H) evolution from ammonia borane (BHNH), a three-fold increase compared to WO, is researched.

Energy transfer from Er to Nd ions by the thermal effect and promotion of the photocatalysis of the NaYF:Yb,Er,Nd/WO heterostructure.

The NaYF4:Yb,Er/W18O49 heterostructure is an excellent photocatalyst that can promote H2 evolution by hydrolyzing BH3NH3 under near-infrared (NIR) light irradiation. At the same time, the photothermal effect can be produced in photocatalytic reactions, which will cause the luminescence efficiency and photocatalytic activity to decrease. Determining how to take advantage of that photothermal effect becomes a major problem.

Near-Infrared-Plasmonic Energy Upconversion in a Nonmetallic Heterostructure for Efficient H Evolution from Ammonia Borane.

Plasmonic metal nanostructures have been widely used to enhance the upconversion efficiency of the near-infrared (NIR) photons into the visible region via the localized surface plasmon resonance (LSPR) effect. However, the direct utilization of low-cost nonmetallic semiconductors to both concentrate and transfer the NIR-plasmonic energy in the upconversion system remains a significant challenge. Here, a fascinating process of NIR-plasmonic energy upconversion in Yb/Er-doped NaYF nanoparticles (NaYF:Yb-Er NPs)/WO nanowires (NWs) heterostructures, which can selectively enhance the upconversion luminescence by two orders of magnitude, is demonstrated.

Strong up-conversion luminescence of rare-earth doped oxide films enhanced by gap modes on ZnO nanowires.

Up-conversion luminescence (UCL) from rare-earth doped oxide (RE) films has great potential for application in fields such as solar cells, bioanalysis, or display technologies. However, the relatively high phonon energy of oxide matrices usually facilitates nonradiative relaxation leading to low UCL efficiency. Herein, we report a three-layer hierarchical structure of Ag/ZnO nanowires (nw-ZnO)/RE composite films, which enhances the UCL of rare-earth doped oxide films.

Multiple Temperature-Sensing Behavior of Green and Red Upconversion Emissions from Stark Sublevels of Er³⁺.

Upconversion luminescence properties from the emissions of Stark sublevels of Er(3+) were investigated in Er(3+)-Yb(3+)-Mo(6+)-codoped TiO₂ phosphors in this study. According to the energy levels split from Er(3+), green and red emissions from the transitions of four coupled energy levels, ²H11/2(I)/²H11/2(II), ⁴S3/2(I)/⁴S3/2(II), ⁴F9/2(I)/⁴F9/2(II), and ²H11/2(I) + ²H11/2(II)/⁴S3/2(I) + ⁴S3/2(II), were observed under 976 nm laser diode excitation. By utilizing the fluorescence intensity ratio (FIR) technique, temperature-dependent upconversion emissions from these four coupled energy levels were analyzed at length.

Temperature sensing and in vivo imaging by molybdenum sensitized visible upconversion luminescence of rare-earth oxides.

A novel high excited state energy transfer pathway to overcome the phonon quenching effect in rare-earth (RE) oxide upconversion (UC) materials is reported. In Er(Tm)-Yb oxide systems, an extraordinary enhancement of UC luminescence efficiency with four orders of magnitude is realized by Mo co-doping. The RE oxides with significant UC efficiency are successfully utilized for temperature sensing and in vivo imaging.

Up-conversion emissions characteristics of non-aqueous sol-gel derived RE3Al5O12 nanocrystals.

The RE3Al5O12 (REAG:Er3Al5O12, Er:Y3Al5O12 and Er:Yb3Al5O12) up-conversion (UC) nanocrystals have been prepared by the non-aqueous sol-gel method. The green and red UC emissions are attributed to the 2H(11/2), 4S(3/2) --> 4I(15/2) and 4F(9/2) --> 4I(15/2) transitions of Er3+, respectively, were obtained for all samples with a 975 nm semiconductor LD excitation. For Er3Al5O12 nanocrystals, the green and red UC emissions have similar intensities.

Local and remote charge-transfer-enhanced Raman scattering on one-dimensional transition-metal oxides.

The one-dimensional (1D) transition-metal oxide MoO(3) belt is synthesized and characterized with X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. Charge-transfer-(CT) enhanced Raman scattering of 4-mercaptobenzoic acid (4-MBA) on a 1D MoO(3) belt was investigated experimentally and theoretically. The chemical enhancement of surface-enhanced Raman scattering (SERS) of 4-MBA on the MoO(3) belt by CT is in the order of 10(3).