Intrinsic quantum yields and radiative lifetimes of lanthanide tris(dipicolinates)

Citations Over TimeTop 10% of 2009 papers

Abstract

The efficiency with which the surroundings of trivalent lanthanide ions sensitize their luminescence (eta(sens)) is a key parameter in the design of highly emitting molecular edifices and materials. Evaluation of eta(sens) requires the measurement of the overall and intrinsic quantum yields obtained upon ligand and metal excitation, respectively. We describe a modified integration sphere enabling absolute determination of these quantities on small amounts of solid samples or solutions (60 muL). The sphere is tested for linear response of emitted versus absorbed light intensities with increasing concentration of Cs(3)[Ln(dpa)(3)] solutions (Ln = Eu, Tb). The overall (Q = 29 +/- 2%) and intrinsic (Q = 41 +/- 2%) quantum yields obtained for Eu allow the direct calculation of eta(sens) (71 +/- 6%) while the radiative lifetime (tau(rad) = 4.1 +/- 0.3 ms) is calculated from Q and the observed lifetime. The intrinsic quantum yield matches the value extracted from emission parameters using the simplified equation proposed by Werts et al. but, on the other hand, the theoretical estimate using spontaneous transition probabilities calculated from Judd-Ofelt (JO) parameters is off by -25% (3.15 ms). In the case of Cs(3)[Tb(dpa)(3)], the molar absorption coefficient of the (5)D(4)(7)F(6) emission and the absorption spectrum of the dipicolinate triplet, this overlap being smaller in the case of the solution. The overall quantum yield of Na(3)[Yb(dpa)(3)] in aqueous solution is very low (0.015 +/- 0.002%) due to both poor sensitization efficiency (8%) and small intrinsic quantum yield (Q = 0.178 +/- 0.003%; tau(rad) = 1.31 +/- 0.02 ms). For evaluating intrinsic quantum yields of Yb in aqueous solutions of coordination compounds from lifetimes, a value of 1.2-1.3 ms is recommended.

Related Papers

• → Near-Quantitative Internal Quantum Efficiency in a Light-Emitting Electrochemical Cell(2008)178 cited
• → Self-absorption correction for solid-state photoluminescence quantum yields obtained from integrating sphere measurements(2007)151 cited
• → High‐Efficiency Near‐Infrared Fluorescent Organic Light‐Emitting Diodes with Small Efficiency Roll‐Off: A Combined Design from Emitters to Devices(2017)59 cited
• → <title>Dye-doped molecular light-emitting diodes with enhanced performance</title>(1998)19 cited
• → Fast and Reliable Measurement of Photoluminescence Quantum Yields for the Development of Fluorescent Probes(2013)