Photoluminescence tuning and energy transfer process from Tb3+ to Eu3+ in GPTMS/TEOS–derived organic/silica hybrid films

Abstract

In this work the photoluminescence study and energy transfer from Tb 3+ to Eu 3+-β-diketonate complexes incorporated into organic/Silica hybrid films derived from 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) alkoxysilanes were investigated. Highly homogeneous and transparent films of Ln 3+-doped GPTMS/TEOS-derived organic/silica hybrids were obtained from the organic/silica sols prepared by sol-gel. Tb 3+ :Eu 3+-doped GPTMS/TEOS-derived films showed very intense luminescence when excited with UV light. Films co-doped with Tb 3+ concentration fixed at 40.0×10 18 ions/cm 3 and Eu 3+ concentrations of 0, 0.03, 0.05, 0.1, 0.3, 0.5, 1.0, 1.5, and 2.0×10 18 ions/cm 3 were studied. The films presented characteristic transitions 5 D 4-7 F 6-3 of Tb 3+ ions and 5 D 0-7 F 0-4 of Eu 3+ ions measured on the visible spectrum region. Energy transfer from Terbium to Europium was studied through emission decay time measurements of 5 D 4-7 F 5 transition of Tb 3+ (547 nm) which showed an accentuated decrease (from 1329 to 55 µs) due to the co-doping with Eu 3+ ions concentrations varied from 0.03 to 1.5×10 18 ions/cm 3. Energy transfer rate (W ET) of 17.4×10 3 s −1 and relative energy transfer efficiency (η T) of 96% were observed for films samples co-doped with 40×10 18 ions/cm 3 of Tb 3+ and 1.5×10 18 ions/cm 3 of Eu 3+. Due to the variation in W ET and η T from Tb 3+ to Eu 3+ , the intensity ratios of Tb 3+ band at 547 nm (5 D 4-7 F 5) and Eu 3+ band at 617 nm (5 D 0-7 F 2) vary remarkably making the co-doped film samples exhibit different luminescence colors varying from green to orange and red which can be tuned by the Tb 3+ /Eu 3+ ratio incorporated into the samples.

Energy Transfer in Mixed Lanthanides Complexes: Toward High‐Performance Pressure Sensors Based on the Luminescence Intensity Ratio

“…[76,77] The considerable reduction in the decay time of the Tb 3+ emission in complexes with Eu 3+ indicates the transfer of energy from the 5 D 4 level of Tb 3+ to excite Eu 3+ . [65,90,92] Figure 4a shows that the decay time of Tb 3+ emission decreases with increasing Eu 3+ concentration, corresponding to the same variation in Eu 3+ rise time (Figure 4b), which can be described by the simplified model Equation ( 1): [5,78,79,[93][94][95] n =…”

“…[ 76,77 ] The considerable reduction in the decay time of the Tb 3+ emission in complexes with Eu 3+ indicates the transfer of energy from the 5 D 4 level of Tb 3+ to excite Eu 3+ . [ 65,90,92 ] Figure 4a shows that the decay time of Tb 3+ emission decreases with increasing Eu 3+ concentration, corresponding to the same variation in Eu 3+ rise time (Figure 4b), which can be described by the simplified model Equation (): [ 5,78,79,93–95 ] $$$$\begin{equation}n{\mathrm{\;}} = \left[ {{n_0} + {n_1}\left( {1 - \exp \left( {\frac{{ - t}}{{{\tau _1}}}} \right)} \right)} \right]{\mathrm{\;}}\exp \left( {\frac{{ - t}}{{{\tau _2}}}} \right)\end{equation}$$$$Where n and n 0 are the number of electrons in the excited level at time t ant t 0 , respectively; τ 2 is the decay time from the upper level; n 1 presents the number of electrons in the feeding level; and τ 1 is the time for feeding this level. This model will be used to fit the Eu 3+ decay‐time curves (Equation S1, Supporting Information), where τ 1 is the decay time of Tb 3+ , fitted by the biexponential decay function (Equation S2, Supporting Information).…”