Hydrothermal Synthesis and Size-Enhanced Chromaticity of Sr₂ZnSi₂O₇:Eu³⁺ Nanoparticles

Abstract

Red phosphor Sr2ZnSi2O7:Eu3+ nanoparticles with an average diameter of 20 nm were successfully synthesized via a low-temperature hydrothermal route in order to understand the underlying relationship between size and luminescent properties. The nanometer-sized particles result in a distinct improvement in chromaticity and a high quenching concentration. According to emission spectra, the relative intensity of the 5D0 --> 7F2 to 5D0 --> 7F1 transitions in nanometer-sized phosphors is higher than that of the corresponding bulk material. The better chromaticity results from the more distorted lattices and relatively lower crystal symmetry around the Eu3+ ions, which is ascribed to the large surface area due to the nanometer size of the phosphor. Moreover, the nanometer-sized Sr2ZnSi2O7:Eu3+ red phosphor exhibits a shorter fluorescent lifetime and a blue-shift in excitation spectra compared to that of its bulk counterpart. These results indicate that size-induced enhancement of luminescent properties is an efficient way to obtain red phosphors with better chromaticity.

A comprehensive study of the effect of in situ annealing at high growth temperature on the morphological and optical properties of self-assembled InAs/GaAs QDs

“…After 50 s of annealing pause the morphological properties of the dots degrade drastically leading to a blue shift in the PL spectra, as mentioned earlier. Some of the above results shown here have already been reported earlier [17], but for the sake of better comprehensiveness and clarity, also have been included in this paper.…”

“…The change in the morphological parameters influences the quantum confinement of the charged carriers in the QDs by modifying their bandgap energy profiles and therefore determines the optical properties and emission wavelength of the heterostructures. In our previous work [17] we have already demonstrated that annealing at high growth temperature during dot pause causes a red shift in the interband photo-response of the self-assembled InAs/GaAs QDs grown by MBE.…”

Inhibition of emission wavelength blueshift in annealed InAs/GaAs quantum dot stacks: an important observation for their potential application in photovoltaic devices

“…In a QD-IBSC, the IB is formed with the introduction of valid quantum states of the QD deep into the previously forbidden band gap of a host semiconductor and can be used for absorption of incident photons in the solar spectrum at energies below the band gap of the GaAs host matrix [5]. The ground state emission peak of InAs/GaAs QD lies typically in between 900 nm to 1200 nm [6,7]. Hence, the use of InAs QD in IBSC will enable a larger portion of the long wavelength region of solar radiation spectrum to be harvested for the photocurrent generation.…”