Investigation of local field effect of α‐NaYF₄:Nd³⁺ nanocrystals

Abstract

Pure α‐NaYF4: Nd3+ nanocrystals of various sizes from 6 nm to 18 nm were successfully synthesized by a solvothermal method. The monodispersed oleate‐capped nanocrystals were dispersed in several nonpolar solvents to obtain stable colloidal. Under the excitation by an 803 nm laser, luminescent decay curves of the colloidal were measured. The relationship between emission lifetimes of samples and effective refractive indices of solvents was studied for the local field correction factor. In the 18 nm sample, the real cavity model was preferable model. As the particle size decreased to 6 nm, the preferred model altered from the real cavity model to the virtual cavity model which might be derived from changing of polarizability density. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of the effective refractive index on the radiative decay rate in nanoparticle thin films

“…4–9,10 However, the simplest approach to changing the LDOS of a light source is to modify the refractive index ( n ) of the medium in which it is embedded, which can easily be done in simple systems such as nanoparticle dispersions by using solvents with different values of n . 11–16 Indeed, an almost cubic dependence of Γ rad on the solvent refractive index has been observed, which has been classically explained by the use of local field cavity models. 17–20 Although this theoretical formalism can be applied to any luminescent nanoparticle, including dye-doped polymer beads or semiconductor quantum dots, most reported examples involve phosphor nanoparticles.…”

“…2,3 Since then, a wide variety of optical materials made of dielectrics and metals, nanostructured at the scale of the targeted photon wavelength, have been used to manipulate the LDOS and thus modify the PL of nanomaterials, including semiconductor nanocrystals, organic molecules or rare earth (RE) phosphor nanoparticles. [4][5][6][7][8][9]10 However, the simplest approach to changing the LDOS of a light source is to modify the refractive index (n) of the medium in which it is embedded, which can easily be done in simple systems such as nanoparticle dispersions by using solvents with different values of n. [11][12][13][14][15][16] Indeed, an almost cubic dependence of Γ rad on the solvent refractive index has been observed, which has been classically explained by the use of local field cavity models. [17][18][19][20] Although this theoretical formalism can be applied to any luminescent nanoparticle, including dye-doped polymer beads or semiconductor quantum dots, most reported examples involve phosphor nanoparticles.…”

The influence of solvent refractive index on the photoluminescence decay of thick‐shell gradient‐alloyed colloidal quantum dots investigated in a wide range of delay times

“…First, the aforementioned Lorentz virtual‐cavity model has been used to calculate $$$ f(n) $$$ for CdSe/ZnS semiconductor QDs [7, 8]. Second, the so‐called real‐cavity model has been used to obtain $$$ f(n) $$$ for Tm 3+ :LaF 3 nanocrystals [9] and for α‐NaYF 4 :Nd 3+ nanocrystals [10]. Third, the so‐called nanocrystal‐cavity model has been successfully used to calculate $$$ f(n) $$$ for LaPO 4 QDs doped with Ce 3+ or Tb 3+ ions [11] as well as for CdSe/CdS/CdZnS/ZnS semiconductor QDs [12].…”