We report the enhancement of both visible and near infrared (NIR) emissions from Nd(3+) ions via Ce(3+) sensitization in colloidal nanocrystals for the first time. This is achieved in citrate capped Nd(3+)-doped CeF3 nanocrystals under ultraviolet (UV) irradiation (λex = 282 nm). The lasing transition ((4)F3/2 → (4)I11/2) at 1064 nm from Nd(3+)-doped CeF3 nanocrystals has much higher emission intensity via Ce(3+) ion sensitization compared to the direct excitation of Nd(3+) ions. The nanocrystals were prepared using a simple microwave irradiation route. Moreover, the study has been extended to Sm(3+)-doped CeF3 nanocrystals which show strong characteristic emissions of Sm(3+) ions via energy transfer from Ce(3+) ions. The energy transfer mechanism from Ce(3+) to Nd(3+) and Sm(3+) ions is proposed.

Lanthanide (Ln)-doped nanocrystals generally display low luminescence quantum efficiency due to forbidden nature of the 4f-4f transition besides possessing low absorption cross sections (∼10 M cm). Considering the demand for these materials, particularly for light emission and bioimaging applications, it is very important to improve their quantum efficiency. This work demonstrates a strategy to enhance Si solar cell efficiency via sensitization of Eu ions luminescence from colloidal nanocrystals. We have for the first time developed a simple ligand exchange approach to attach 4,4,4-trifluoro-1-phenyl-1,3 butanedione (TPB) to the surface of Eu-doped LiYF nanocrystals (NCs). Owing to the good overlap between the emission of the TPB ligands and the energy levels of Eu ions, an efficient energy transfer takes place from the ligand to Eu ions upon ultraviolet (UV) excitation of the ligand, leading to intense red emission. The sensitization of Eu ions greatly enhanced the quantum yield of Eu ions (∼31%) compared to the ∼5% obtained via direct excitation of Eu ions (λ = 394 nm) in Eu-doped LiYF NCs. A device was fabricated by embedding the nanocrystals on a Si solar cell to capture the UV photons and convert them into visible ones, which subsequently creates charge carriers inside the cell. Upon exposure to UV light, the nanocrystal embedded Si solar cell shows overall enhancement in the photocurrent upon excitation under UV radiation.

In this communication we report the observation of intense near infrared (NIR) emissions in the 900 nm to 2000 nm range from colloidal water dispersible lanthanide (Ln3+) doped GdVO4 nanocrystals (Ln = Sm3+, Nd3+, Dy3+, Tm3+, Er3+ and Ho3+).

This study provides new insight towards the non-classical “amorphous to crystalline” growth mechanism for metal nanowire synthesis and reports an electrochemical strategy to activate inactive materials into efficient electrocatalysts for the OER.

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