Enhancement of Temperature Fluorescence Brightness of Zn@Si Core-Shell Quantum Dots Produced via a Unified Strategy

Abstract

Despite many dedicated efforts, the fabrication of high-quality ZnO-incorporated Zinc@Silicon (Zn@Si) core–shell quantum dots (ZnSiQDs) with customized properties remains challenging. In this study, we report a new record for the brightness enhancement of ZnSiQDs prepared via a unified top-down and bottom-up strategy. The top-down approach was used to produce ZnSiQDs with uniform sizes and shapes, followed by the bottom-up method for their re-growth. The influence of various NH4OH contents (15 to 25 µL) on the morphology and optical characteristics of ZnSiQDs was investigated. The ZnSiQDs were obtained from the electrochemically etched porous Si (PSi) with Zn inclusion (ZnPSi), followed by the electropolishing and sonication in acetone. EFTEM micrographs of the samples prepared without and with NH4OH revealed the existence of spherical ZnSiQDs with a mean diameter of 1.22 to 7.4 nm, respectively. The emission spectra of the ZnSiQDs (excited by 365 nm) exhibited bright blue, green, orange-yellow, and red luminescence, indicating the uniform morphology related to the strong quantum confinement ZnSiQDs. In addition, the absorption and emission of the ZnSiQDs prepared with NH4OH were enhanced by 198.8% and 132.6%, respectively. The bandgap of the ZnSiQDs conditioned without and with NH4OH was approximately 3.6 and 2.3 eV, respectively.

Photovoltaic Performance of Spherical TiO2 Nanoparticles Derived from Titanium Hydroxide Ti(OH)4: Role of Annealing Varying Temperature

“…The P-Si layer revealed indirectly to direct band gap energy transition due to the quantum confinement effect, which was due to the shrinkage of Si particle size below 5 nm [35,36]. The value of 𝐸𝑔 for PSi (~2.78 eV) was comparable with the one obtained previously (2.2 eV) from the photoluminescence spectral analyses [37][38][39]. The solar simulator was used to determine the cell characterization, which gives the value automatically.…”

Performance Improvement of Graded Bandgap Solar Cell via Optimization of Energy Levels Alignment in Si Quantum Dot, TiO2 Nanoparticles, and Porous Si

“…The variation of NH 4 OH amount considerably affected the morphologies (sizes and shapes) of ZnSiQDs, causing the QDs size distribution to become more uniform with reduced inter-particle spacing. In short, the addition of NH 4 OH into the colloidal ZnSiQDs suspension enabled the re-growth of tinier nanoparticles and the formation chain through a central core [37,38].…”