Sensitization of Lanthanide (Ln³⁺) ion Luminescence in Ln³⁺ -doped Nanomaterials

Samanta, Tuhin (2018) Sensitization of Lanthanide (Ln³⁺) ion Luminescence in Ln³⁺ -doped Nanomaterials. PhD thesis, Indian Institute of Science Education and Research Kolkata.

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Abstract

Lanthanides (Ln³⁺) ions have very unique optical properties such as large downshifting, downconversion, upconversion, high signal to noise ratio, narrow emission band, etc. Generally these properties are observed in Ln³⁺ based complexes and Ln3+ doped materials. Ln³⁺ doped materials have advantages over complexes as materials are more robust and favourable for device fabrication. However, main drawbacks of the Ln³⁺ doped materials are the low absorbance coefficiency and narrow absorbance band of the Ln³⁺ ions. The low luminescence quantum efficiency of the Ln³⁺ doped materials can be improved via sensitization of the luminescence. This section discusses some of the sensitization methods developed to increase the luminescence efficiency of Ln³⁺ doped materials. In addition, sensitization of near infrared emission is less addressed compared to visible emissions, particularly in colloidal disersions. This can be challenging given the high probability of nonradiative relaxation in aqueous medium. In second chapter, we have discussed the observation of very strong Eu³⁺ ions luminescence via sensitization by carbon dots (C dots) in Eu³⁺ doped LaF3–C dot nanocomposites. In the third chapter, demonstrates a strategy to enhance Si solar cell efficiency via sensitization of Eu³⁺ ions luminescence from colloidal nanocrystals. In the fourth chapter we report the sensitization of NIR luminescence from Ln³⁺ ions in Ln³⁺ doped nanocrystals. In the fifth chapter, we have discussed about the sensitization of NIR emission of Ln³⁺ ions. In the sixth chapter, we have shown the enhancement of Eu³⁺ ions luminescnec by tuning the pahse and morphology of the GdF₃ nanocrystals. The high luminescence efficiency of the Eu³⁺ doped GdF₃ nanocrystals together with high dispersibility in water can have potential use in bioimaging and MRI imaging applications.

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