Síntese e avaliação fotoluminescente de filmes poliméricos de PMMA e PVDF baseados em complexos de európio(III) e térbio(III) utilizando derivados de β –dicetonas
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Data
2021-10-06
Autores
Beltrame, Ariane Carolina Ferreira
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Universidade Estadual Paulista (Unesp)
Resumo
Visando a aplicação em dispositivos de iluminação, este trabalho teve como objetivo a síntese e caracterização de filmes produzidos via método “drop-casting” baseados em complexos tetraquis de dibenzoilmetanato (Hdbm) de európio(III), para emissão na região do vermelho, e de acetilacetonato (Hacac) de térbio(III) para emissão na região do verde, utilizando os polímeros polimetil-metacrilato (PMMA) e fluoreto de polivinilideno (PVDF). Os complexos tetraquis [C26H56N+][Eu(dbm)4] e Na[Tb(acac)4] foram obtidos com sucesso e sem a presença de moléculas de água na esfera de coordenação, tendo suas propriedades caracterizadas por meio das técnicas de FTIR, TGA, MALDI-TOF, análise elementar, UV-Vis e fotoluminescência. No caso do complexo [C26H56N+][Eu(dbm)4], filmes suportados em PMMA ou PVDF, nas concentrações 0,1%, 0,25%, 0,5%, 0,75%, 1%, 2% e 5% foram produzidos. Já para o complexo Na[Tb(acac)4], tanto para os filmes em PMMA como PVDF, as concentrações utilizadas foram 0,5%, 0,75%, 1%, 2% e 5%. Todos os filmes tiveram suas propriedades luminescentes avaliadas tendo sido observado que a concentração dos complexos em meio aos dois polímeros, modifica os parâmetros foto físicos analisados (tempo de vida, rendimento quântico intrínseco e rendimento quântico absoluto), mas não uniformemente, pois em altas concentrações os complexos tendem a formar aglomerados. Dentre as séries de filmes poliméricos emissores no vermelho, tanto em PVDF quanto em PMMA, aqueles com a concentração de 1% do complexo de Eu(III) foram considerados os candidatos mais promissores para a fabricação de protótipos de LED. Já no caso dos filmes emissores no verde, a concentração de 5% do complexo tetraquis de térbio(III) resulta em um sistema mais adequado a ser utilizado na produção dos dispositivos de iluminação. A escolha entre os dois polímeros, em cada caso, no entanto, dependerá da produção do protótipo e do monitoramento dos parâmetros relacionados ao funcionamento do LED.
In the search for lighting devices application, the aim of this study was the synthesis and characterization of films via the “drop-casting” method based on tetrakis complexes of dibenzoylmetanate (Hdbm) of europium(III), for emission in the red region, and of terbium(III) acetylacetonate (Hacac) for emission in the green region, using the polymers polymethyl-methacrylate (PMMA) and polyvinylidene fluoride (PVDF). The tetrakis complexes [C26H56N+][Eu(dbm)4] and Na[Tb(acac)4] were successfully obtained without water molecules in the coordination sphere, and their properties were characterized using FTIR, TGA, MALDI-TOF, elemental analysis, UV-Vis and photoluminescence techniques. In the case of the [C26H56N+][Eu(dbm)4] complex, films supported on PMMA or PVDF, in concentrations of 0.1%, 0.25%, 0.5%, 0.75%, 1%, 2% and 5% were produced. As for the Na[Tb(acac)4] complex, for both PMMA and PVDF films, the concentrations used were 0.5%, 0.75%, 1%, 2% and 5%. All films had their luminescent properties evaluated and it was observed that the concentration of the complexes embedded in the two polymers modifies the analyzed photophysical parameters (lifetime, intrinsic quantum yield and absolute quantum yield), but not uniformly, as at high complexes concentrations tend to form clusters. Among the series of red-emitting polymeric films, both in PVDF and in PMMA, those with a concentration of 1% of the Eu(III) complex were considered the most promising candidates for manufacturing LED prototypes. In the case of green-emitting films, the 5% concentration of terbium(III) tetrakis complex results in a more suitable system to be used in the production of lighting devices. The choice between the two polymers, in each case, however, will depend on the production of the prototype and the monitoring of the parameters related to the LED operation.
In the search for lighting devices application, the aim of this study was the synthesis and characterization of films via the “drop-casting” method based on tetrakis complexes of dibenzoylmetanate (Hdbm) of europium(III), for emission in the red region, and of terbium(III) acetylacetonate (Hacac) for emission in the green region, using the polymers polymethyl-methacrylate (PMMA) and polyvinylidene fluoride (PVDF). The tetrakis complexes [C26H56N+][Eu(dbm)4] and Na[Tb(acac)4] were successfully obtained without water molecules in the coordination sphere, and their properties were characterized using FTIR, TGA, MALDI-TOF, elemental analysis, UV-Vis and photoluminescence techniques. In the case of the [C26H56N+][Eu(dbm)4] complex, films supported on PMMA or PVDF, in concentrations of 0.1%, 0.25%, 0.5%, 0.75%, 1%, 2% and 5% were produced. As for the Na[Tb(acac)4] complex, for both PMMA and PVDF films, the concentrations used were 0.5%, 0.75%, 1%, 2% and 5%. All films had their luminescent properties evaluated and it was observed that the concentration of the complexes embedded in the two polymers modifies the analyzed photophysical parameters (lifetime, intrinsic quantum yield and absolute quantum yield), but not uniformly, as at high complexes concentrations tend to form clusters. Among the series of red-emitting polymeric films, both in PVDF and in PMMA, those with a concentration of 1% of the Eu(III) complex were considered the most promising candidates for manufacturing LED prototypes. In the case of green-emitting films, the 5% concentration of terbium(III) tetrakis complex results in a more suitable system to be used in the production of lighting devices. The choice between the two polymers, in each case, however, will depend on the production of the prototype and the monitoring of the parameters related to the LED operation.
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Palavras-chave
Íons terras raras, Emissor no vermelho, Emissor no verde, Luminescência, DBM, ACAC, Rare earth ions, Red emitter, Green emitter, Luminescence, LEDs