Luminescence thermometry is being addressed as one of the most promising techniques to non-contact measurement of temperature with sub-micrometric resolution, due to the possibility of design the thermometer performance by the smart combination of emitting centers, ligands and host matrix. Numerous applications in microelectronic circuits and photonic devices will benefit of improved spatial and temporal resolution in the temperature imaging. In this paper we report three Ln3+-based (Ln=Eu, Tb) molecular thermometers co-doping an organic–inorganic hybrid matrix with Eu3+/Tb3+ chelates that differ in the ligand used. We show that the sensitivity of such thermometers can be tuned from 0.042±0.002 to 3.0±0.4%•K−1, in the 295–330K range, through the wisest design of the ligand (and the ligand-hybrid host interactions). The maximum sensitivity value is one of the largest reported so far for luminescent ratiometric thermometers. Furthermore, we rationalize the increase on the performance of the molecular thermometers using a partial energy scheme involving the emitting levels of the Ln3+ ions and the singlet and triplet states of the ligands and the hybrid host.

An integrated variable wave plate device based on a thermo-optic (TO) effect was fabricated by patterning a waveguide channel through direct UV laser writing on the surface of sol-gel derived organic-inorganic hybrid (di-ureasil) films. The di-ureasil layer is stable up to 250 °C and has a high TO coefficient calculated as -(4.9 ± 0.5) × 10(-4) °C(-1) at 1550 nm. The waveguide temperature was tuned, inducing optical phase retardation between the transverse electric and transverse magnetic modes, resulting in a controllable wave plate. A maximum phase retardation of 77 ° was achieved for a waveguide induced temperature increase of 5 °C above room temperature, with a power consumption of 0.4 W. The thermal linear retardation coefficient was calculated to be 19 ± 1 °/ °C.

A mixed lanthanide β-diketonate complex of molecular formula [Eu0.45Tb0.55(btfa)3(4,4′-bpy)(EtOH)] (btfa–=4,4,4–trifluoro–1–phenyl–1,3–butanedionate; 4,4′-bpy=4,4′-dipyridyl; EtOH=ethanol) was synthesized and its structure was elucidated by single crystal X-ray diffraction. The temperature dependence of the complex emission intensity between 11 and 298K is illustrated by the Commission Internacionale l’Éclairage (CIE) (x,y) color coordinates change within the orange-red region, from (0.521, 0.443) to (0.658, 0.335). The existence of Tb3+-to-Eu3+ energy transfer was observed at room temperature and as the complex presents a relatively high emission quantum yield (0.34±0.03) it was doped in a 4,4′-bis(carbazol-9-yl)biphenyl (CBP) organic matrix to be used as emitting layer to fabricate a white organic light-emitting diode (WOLED). Continuous electroluminescence emission was obtained varying the applied bias voltage showing a wide emission band from 400 to 700nm. The white emission results from a combined action between the Eu3+ and Tb3+ peaks from the mixed Eu3+/Tb3+ complex and the other organic layers forming the device. The intensity ratio of the peaks is determined by the layer thickness and by the bias voltage applied to the OLED, allowing us to obtain a color tunable light source.

The rare-earth metal organic chelate [Eu(btfa)3(MeOH)(bpeta)] (btfa, 4,4,4-trifluoro-1-phenyl-1,3-butanedionate; bpeta, 1,2-bis(4-pyridyl)ethane) has been used to dope a plastic optical fibre (POF) prepared by the bulk homopolymerization of hexamethylene diisocyanate (HMDI) catalysed by Tin(II)-2 ethylhexanoate (SnOct), to obtain a plastic optical fibre amplifier (POFA). The Eu3+ chelate, primarily added as luminophore for the amplification of the optical signal, showed an interesting co-catalytic activity in the polymerization of HMDI, that preferentially proceeded towards the formation of the highly stable polyisocyanurate trimer form thanks to its selective driving action, as demonstrated by 13C solid-state NMR. Pumping of the POFA with xenon lamps demonstrated the occurrence of stimulated emission inside the doped fibre.

In this work, we report an integrated tunable wave-plate based on thermo-optic (TO) effect on a waveguide patterned by direct UV laser writing on films of organic-inorganic hybrid materials. The temperature of the waveguide was tuned inducing phase retardation between transverse electric and transverse magnetic modes. The TO coefficient of the planar waveguide is (-4.9±0.3)×10-4°C-1 at 1550 nm. A maximum phase retardation of 77° was achieved for a temperature variation of 5 oC, with a power consumption of 435 mW. The transformations of the state of polarization between linear and circular were visualized on the Poincaré sphere.

Transparent monoliths and films of urea cross-linked tripodal siloxane-based hybrids (named tri-ureasils) were prepared by the sol–gel process, under controlled atmosphere (inside a glove box) and ambient conditions and their structure and optical features were compared. X-ray diffraction data point out that all the materials are essentially amorphous and 29Si NMR reveal an increase in the condensation degree (0.97) for the hybrids prepared under controlled atmosphere relatively to that found for those prepared under ambient conditions (0.84–0.91). The tri-ureasils are white light emitters under UV/Visible excitation (from 250 to 453 nm) being observed for the composites prepared inside the glove box a significant enhancement (60–80 %) of the absorption coefficient and higher emission quantum yield values (~0.27 and ~0.20 for monoliths and films, respectively) relatively to those synthesized under ambient condition.

This work reports a variable attenuator/waveplate based on thermo-optic (TO) effect induced on a waveguide patterned by direct UV-laser writing on films of organic-inorganic di-ureasil hybrids. The waveguide temperature was tuned inducing phase retardation between the transverse electric (TE) and transverse magnetic (TM) modes, resulting in a controllable waveplate. Furthermore, the waveguide TO actuation allows obtaining a variable optical attenuator. The relevant properties, such as attenuation, polarization dependence of the thermal actuation and power consumption will be presented in the NIR (1550 nm). The required electrical power and temperature variation to attain the optical signal extinction and the retardation phase of π/2 were estimated.

This work reports the synthesis of novel sol–gel derived urea cross-linked tripodal siloxane-based hybrids (classed as tri-ureasils) modified by the addition of phenyltriethoxysilane (PTES) and diphenyldimethoxysilane (DPDMS). The materials were produced as transparent monoliths and thin films (thickness = 3.3–17.5 ± 0.1 μm) and characterized by X-ray diffraction, mid-infrared spectroscopy, 29Si and 13C nuclear magnetic resonance, thermogravimetric analysis, ultraviolet/visible (UV/Vis) absorption and photoluminescence spectroscopies. The role played by PTES and DPDMS as light harvesting chromophores has been discussed and quantified through emission quantum yield and UV/Vis absorption measurements. All the hybrids show efficient emission at room temperature in the blue spectral region with maximum emission quantum yield values ranging from 0.01 ± 0.001 to 0.10 ± 0.01. The highest values were found for the tri-ureasils incorporating PTES and DPDMS essentially due to an increase in the absorption coefficient (from 1.4 × 103 cm−1, for the pristine tri-ureasil, to 8.6 × 103 cm−1, for the hybrids modified by the chromophores). The existence of energy transfer between the DPDMS and PTES excited states and the hybrid host intrinsic emitting levels (NH/C=O- and siliceous-related levels) has been discussed.

We report the fabrication of thermo-optic optical attenuators produced by direct UV laser writing in transparent, low surface roughness, and low-loss thin films of organic-inorganic hybrids, so called di-ureasils. The signal propagation and attenuation were demonstrated for propagation signals at 635.0 nm and 1550.0 nm, showing a power reduction up to 75% with a temperature gradient of -16.1 K·mm-1 and -7.6 K·mm-1 at 635.0 nm and 1550.0 nm, respectively.

Organic–inorganic hybrids incorporating Tb(acac)3·3H2O (where acac is acetylacetonate) were synthesized via conventional hydrolysis sol–gel reaction in the presence and absence of an acid catalyst (hydrochloric acid, HCl). The host framework of these materials, named di-ureasils, is formed by polyether-based chains grafted to both ends to a siliceous backbone through urea cross-linkages (–NHC(CO)NH–). Four different concentrations of HCl (0.5, 1.0, 1.5, and 2.0molL−1) were used as catalyst for hydrolysis reactions. The gelation time of the resulting materials depends on the HCl concentration varying between 5 and 20min. The hybrids were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 29Si and 13C magic-angle spin nuclear magnetic resonance (NMR) and photoluminescence spectroscopy. The emission quantum yield for the undoped hybrids lies between 8.7 and 10.6%, much higher than those obtained for analogous samples prepared via conventional hydrolysis in the absence of catalyst. For the Tb3+-containing hybrids the lanthanide local environment was affected due to different synthetic conditions used. An increase in the 5D4 lifetime values, relatively to that of the isolated Tb(acac)3·3H2O complex, is in good agreement with a smaller 5D4 non-radiative transition probability in the hybrids suggesting the replacement of the Tb3+coordinated water molecules by the oxygen atom of the carbonyl group of the di-ureasil host.

In this work, the fabrication and the characterization of a white triple-layer OLED using a β-diketones binuclear complex [Eu(btfa)3phenterpyTb(acac)3] as the emitting layer is reported. The devices were assembled using a heterojunction between three organic molecular materials: the N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPB) as hole-transporting layer, the β-diketones binuclear complex and the tris(8-hydroxyquinoline aluminum) (Alq3) as the electron transporting layer. All the organic layers were sequentially deposited under high vacuum environment by thermal evaporation onto ITO substrates and without breaking vacuum. Continuous electroluminescence emission was obtained varying the applied bias voltage from 10 to 22 V showing a wide emission band from 400 to 700 nm with about 100 cd/m2 of luminance. The white emission results from a combined action between the binuclear complex, acting as hole blocking and emitting layer, blue from NPB and the typical Alq3 green emission. The intensity ratio of the peaks is determined by the layer thickness and by the bias voltage applied to the OLED, allowing us to obtain a color tunable light source.

New europium and gadolinium tris-beta-diketonate complexes have been prepared and incorporated in sol-gel-derived organic-inorganic hybrids, named di-ureasils. The general formula [Ln(btfa)3(4,4'-bpy)(EtOH)] (Ln=Eu, Gd; 4,4'-bpy=4,4'-bipyridine; btfa=4,4,4-trifluoro-1-phenyl-1,3-butanedione) for the complexes was confirmed by X-ray crystallography and elemental analysis. The ground-state geometry of the Eu3+ complex was calculated from the Sparkle/AM1 model. The calculated quantum yield obtained from the Sparkle model and from the crystal structure (both 46%) are in satisfactory agreement with the experimental value (38+/-4%). In the isolated complex the most efficient luminescence channel is S0-->S1-->T-->(5D1, 5D0)-->7F0-6, where the exchange mechanism dominates in the energy-transfer channel T-->(5D1, 5D0). For the Eu3+-based di-ureasils a 50% quantum yield enhancement compared to the Eu3+ complex is observed, which suggests an effective hybrid host-metal ion interaction and an active energy-transfer channel between the hybrid host and the Eu3+ complex. The Eu3+-based di-ureasils are photostable under UVA (360 nm) excitation, whereas under UVB (320 nm) and UVC (290 nm) photodegradation occurs.

Tris(beta-diketonato)europium(III) complexes of general formula [Eu(TPI)(3)-L], with chelating ligands such as 3-phenyl-4-(4-toluoyl)-5-isoxazolone (HTPI) and adduct-forming reagents [L = H2O, tri-n-octylphosphane oxide (TOPO), triphenylphosphane oxide (TPhPO), 1,10-phenanthroline], have been synthesized and characterized by elemental analysis and FT-IR, H-1 NMR, and photoluminescence spectroscopy. The coordination geometries of the complexes were calculated using the Sparkle/AM1 (Sparkle model for the calculation of lanthanide complexes within the Austin model 1) model. The ligand-Eu3+ energy-transfer rates were calculated using a model of intramolecular energy transfer in lanthanide coordination complexes reported in the literature. The room-temperature PL spectra of the europium(III) complexes are composed of the typical Eu (3+) red emission, assigned to transitions between the first excited state (5 DO) and the multiplet (F-7(0-4)). The results clearly show that the substitution of water molecules by TOPO leads to greatly enhanced quantum yields (i.e., 1.3% vs. 49.5%) and longer D-5(0) lifetimes (220 vs. 980 mu s). This can be ascribed to a more efficient ligand-to-metal energy transfer and a less efficient nonradiative D-5(0) relaxation process. The theoretical quantum yields are in good agreement with the experimental quantum yields, which highlights that the present theoretical approach can be a powerful tool for the a priori design of highly luminescent lanthanide complexes. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).

Complexes of Eu3+, Tb3+ and Gd3+ with dipicolinic acid, chelidamic acid and chelidonic acid have been synthesized in order to study the effect of the substituent groups on the luminescence of the lanthanide complexes. The luminescence of the Eu3+ and Tb3+ complexes was quantified by quantum yield measurements. The complexes of Gd3+ have been used to determine the energies of the triplet states of the ligands. The Tb3+ complex synthesized with dipicolinic acid presented the highest quantum yield due to the energy difference between the triplet state of the dipicolinic acid and the emitting level of the Tb3+ ion.