Ag-Sensitized {NIR}-Emitting Yb3mathplusmathplus-Doped Glass-Ceramics

Featured Applicationdownshifting layers for silicon solar cells, NIR emitting devices and lasers.Abstract The optical photoluminescent (PL) emission of Yb3+ ions in the near infrared (NIR) spectral region at about 950-1100 nm has many potential applications, from photovoltaics to lasers and visual devices. However, due to their simple energy-level structure, Yb3+ ions cannot directly absorb UV or visible light, putting serious limits on their use as light emitters. In this paper we describe a broadband and efficient strategy for sensitizing Yb3+ ions by Ag codoping, resulting in a strong 980 nm PL emission under UV and violet-blue light excitation. Yb-doped silica-zirconia-soda glass-ceramic films were synthesized by sol-gel and dip-coating, followed by annealing at 1000 degrees C. Ag was then introduced by ion-exchange in a molten salt bath for 1 h at 350 degrees C. Different post-exchange annealing temperatures for 1 h in air at 380 degrees C and 430 degrees C were compared to investigate the possibility of migration/aggregation of the metal ions. Studies of composition showed about 1-2 wt% Ag in the exchanged samples, not modified by annealing. Structural analysis reported the stabilization of cubic zirconia by Yb-doping. Optical measurements showed that, in particular for the highest annealing temperature of 430 degrees C, the potential improvement of the material's quality, which would increase the PL emission, is less relevant than Ag-aggregation, which decreases the sensitizers number, resulting in a net reduction of the PL intensity. However, all the Ag-exchanged samples showed a broadband Yb3+ sensitization by energy transfer from Ag aggregates, clearly attested by a broad photoluminescence excitation spectra after Ag-exchange, paving the way for applications in various fields, such as solar cells and NIR-emitting devices

Structural and photophysical properties of rare-earth complexes encapsulated into surface modified mesoporous silica nanoparticles

The encapsulation of [Eu(dbm)3phen] into functionalized mesoporous silica nanoparticles (MSN) has been carried out to study the effect of chemical environments on the photoluminescence properties of the rare-earth complex. Surface functionalization was achieved by the reaction of the silanol groups on the surface of mesoporous silica with different organosilylating agents such as (3-aminopropyl)-triethoxysilane (APTES), (3-mercaptopropyl)-trimethoxysilane (MPTMS), and ethoxytrimethylsilane (ETMS). A change in the luminescence properties of the Eu(dbm)3phen complex has been observed on its encapsulation into surface modified mesoporous silica nanoparticles. The modification of photophysical properties is attributed to the interaction of Eu(dbm)3phen with the different chemical environments in the functionalized mesoporous silica nanoparticles (MSN). The luminescence properties of the rare-earth complex in surface-modified MSN increase in the order MSN < MSN–ETMS < MSN–MPTMS < MSN– APTES. The Eu(dbm)3phen complex encapsulated in the functionalized mesoporous silica nanoparticles shows an enhanced luminescence and an increased lifetime compared to the pure rare-earth complex in the solid state and that in unmodified MSN. This implies that some interactions of the lanthanide complexes take place during their incorporation process into the organically modified mesoporous silica nanoparticles. The organically modified mesoporous silica nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR) and N2 adsorption desorption measurements. The luminescence properties of the encapsulated Eu(dbm)3phen were studied in detail. Moreover, the effect of functionalized MSNs on the structural behaviour of the Eu(dbm)3phen was investigated by solid state nuclear magnetic resonance (SSNMR) techniques using an analogous diamagnetic model complex, Y(dbm)3phen, encapsulated into functionalized MSNs. These studies indicate that the encapsulated rare-earth complex shows some interactions with the functional groups anchored on the surface of MSNs

Structural and photophysical properties of rare-earth complexes encapsulated into surface modified mesoporous silica nanoparticles

The encapsulation of [Eu(dbm)3phen] into functionalized mesoporous silica nanoparticles (MSN) has been carried out to study the effect of chemical environments on the photoluminescence properties of the rare-earth complex. Surface functionalization was achieved by the reaction of the silanol groups on the surface of mesoporous silica with different organosilylating agents such as (3-aminopropyl)-triethoxysilane (APTES), (3-mercaptopropyl)-trimethoxysilane (MPTMS), and ethoxytrimethylsilane (ETMS). A change in the luminescence properties of the Eu(dbm)3phen complex has been observed on its encapsulation into surface modified mesoporous silica nanoparticles. The modification of photophysical properties is attributed to the interaction of Eu(dbm)3phen with the different chemical environments in the functionalized mesoporous silica nanoparticles (MSN). The luminescence properties of the rare-earth complex in surface-modified MSN increase in the order MSN < MSN–ETMS < MSN–MPTMS < MSN– APTES. The Eu(dbm)3phen complex encapsulated in the functionalized mesoporous silica nanoparticles shows an enhanced luminescence and an increased lifetime compared to the pure rare-earth complex in the solid state and that in unmodified MSN. This implies that some interactions of the lanthanide complexes take place during their incorporation process into the organically modified mesoporous silica nanoparticles. The organically modified mesoporous silica nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR) and N2 adsorption desorption measurements. The luminescence properties of the encapsulated Eu(dbm)3phen were studied in detail. Moreover, the effect of functionalized MSNs on the structural behaviour of the Eu(dbm)3phen was investigated by solid state nuclear magnetic resonance (SSNMR) techniques using an analogous diamagnetic model complex, Y(dbm)3phen, encapsulated into functionalized MSNs. These studies indicate that the encapsulated rare-earth complex shows some interactions with the functional groups anchored on the surface of MSNs