Engineering highly efficient Eu(III)-based tri-ureasil hybrids toward luminescent solar concentrators

abstract

Following a computational-experimental approach, a highly luminescent beta-diketonate-europium(III) complex containing 2-thenoyltrifluoracetonate (tta(-)) and 5,6-epoxy-5,6-dihydro-[1,10] phenanthroline (ephen) ligands, Eu(tta)(3)ephen (II), was theoretically studied by DFT/TD-DFT calculations, synthesized from Eu(tta)(3)(H2O)(2)(I) and fully characterized by high resolution mass spectrometry, TGA analysis, vibrational, UV-Vis and photoluminescence spectroscopy. For intramolecular energy transfer analysis purpose, Ln(NO3)(3)(ephen)(2) [Ln = Eu (III), Gd (IV)] complexes were also synthesized and complexes I and III were theoretically studied. The organic-inorganic tri-ureasil matrix was used as a support for the immobilization of complex II and two hybrid samples were synthesized as a monolith (MtU5Eu-II) and as a thin film (FtU5Eu-II), characterized and its photoluminescence properties were compared with those of complex II. The photophysical properties of complex II benefit from the synergy between the excited-states of both ligands that create efficient energy transfer pathways to optimize the Eu3+ sensitization contributing to the large emission quantum yield (82 +/- 8%), which is one of the highest so far reported for solid lanthanide beta-diketonate complexes. Moreover, although the incorporation of complex II into the hybrid matrix is disadvantageous from the quantum yield point of view, MtU5Eu-II and FtU5Eu-II exhibit the highest emission quantum yields reported so far for Eu3+-containing hybrids (63 +/- 6% and 48 +/- 5%, respectively). Additionally, a significant improvement in the photostability under UV irradiation of the incorporated complex II is observed. The possibility of FtU5Eu-II to be used as a luminescent solar concentrator was evaluated and an optical conversion efficiency of similar to 9% as well as an ability to boost up the Si-photovoltaic cell output to 0.5% were verified.

keywords

INTRAMOLECULAR ENERGY-TRANSFER; ORGANIC-INORGANIC HYBRIDS; BETA-DIKETONATE COMPLEX; EMISSION QUANTUM YIELD; RARE-EARTH COMPLEX; SPECTROSCOPIC PROPERTIES; EUROPIUM COMPLEXES; AROMATIC LIGANDS; EU-III; SILICA

subject category

Chemistry; Energy & Fuels; Materials Science

authors

Nolasco, MM; Vaz, PM; Freitas, VT; Lima, PP; Andre, PS; Ferreira, RAS; Vaz, PD; Ribeiro-Claro, P; Carlos, LD

Groups

1 - inorganic functional nanomaterials and organic-inorganic hybrids
6 - computer simulation and multiscale modeling

Projects

Centre for Research in Ceramics and Composite Materials - CICECO (LA0011: 2011-2012) (PEst-C/CTM/LA0011/2011)

Organic-inorganic hybrids with enhanced light-emitting properties for the new generation of optical communications (PTDC/CTM/101324/2008)

acknowledgements

The authors are grateful to Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), COMPETE and FEDER programs (Pest-C/CTM/LA0011/2011, PEst-OE/QUI/UI0612/2011, PTDC/CTMNAN/112168/2009, PTDC/CTM/101324/2008) and Laboratorio Associado CICECO (by granting access to the Flamingo multi-processor cluster). The Portuguese National Mass-Spectrometry Network (REDE/1501/REM/2005) is also acknowledged. MMN (SFRH/BPD/32103/2006), PPL (SFRH/BPD/34365/2006) and VTF (SFRH/BD/87403/2012) acknowledge FCT for a research grant.