Synthesis of Monodisperse Silicon Quantum Dots Through a K-Naphthalide Reduction Route

Abstract

Si quantum dots (Si q-dots) with a size below *5 nm have great potential in electronics and photovoltaics and are candidate materials for down conversion of light due to their strong photoluminescence (PL) properties. Proper control of size and size distribution as well as the surface characteristics of the Si q-dots are critical for applications in order to control the PL response. Here we report on the synthesis of Si q-dots by a chemical route using potassium-naphthalide as a reducing agent. A narrow size distribution of the Si q-dots, with size in the range from 3 to 30 nm, was achieved by controlling the concentration of the reduction agent, the concentration of silicon tetrachloride (SiCl 4 ) precursor, temperature and the reaction time. The crystallinity and the narrow size distribution of Si q-dots were demonstrated by electron microscopy and electron diffraction. The optical absorption and PL response in the blue region of the visible spectrum is reported for 3.1 ± 0.6 nm octanoxy capped Si q-dots and 4.2 ± 1.4 nm methoxy capped Si q-dots in 1,2-dimethoxyethane solution. A quantum efficiency of (1.63 ± 0.16) 9 10 -3 % was detected for the octanoxy terminated Si q-dots.

Silicon‐Based Dielectric Metamaterials: Focus on the Current Synthetic Challenges

“…[90] Thelargest particle size obtained was 27 AE 4.8 nm by SiCl 4 reduction using potassium naphthalide.T he increase of SiCl 4 /potassium naphthalide ratio from 0.224 to 0.289 permits at en-fold increase (respectively from 3.1 AE 0.6 nm to 27 AE 4.8 nm) in the size of Si nanoparticles.Afast nucleation, as explained by the LaMer mechanism, due to ah igh concentration of the potassium naphthalide increased the number of nuclei and hence small, crystalline Si particles were formed. [90] Thelargest particle size obtained was 27 AE 4.8 nm by SiCl 4 reduction using potassium naphthalide.T he increase of SiCl 4 /potassium naphthalide ratio from 0.224 to 0.289 permits at en-fold increase (respectively from 3.1 AE 0.6 nm to 27 AE 4.8 nm) in the size of Si nanoparticles.Afast nucleation, as explained by the LaMer mechanism, due to ah igh concentration of the potassium naphthalide increased the number of nuclei and hence small, crystalline Si particles were formed.…”

Colloidal silicon quantum dots: synthesis and luminescence tuning from the near-UV to the near-IR range

“…Therefore, alkoxylation is an efficient pathway for surface passivation [32, 60–62]. In addition to sodium, the use of potassium is also available [63]. The Kauzlarich group has solution routes extensively studied [58–60, 64–67].…”

Herausforderungen bei der Synthese siliciumbasierter dielektrischer Metamaterialien

“…Natriumnaphthalid, Natriumcyclopentadienid und Kaliumnaphthalid werden eingesetzt, um SiCl 4 zu reduzieren und Si‐Nanokristalle bei Umgebungstemperatur zu synthetisieren. Die Reduktion von Si‐Salzen geschieht durch Ein‐Elektronen‐Transfer vom Radikalanion.…”

“…Wie Balci et al. berichteten, veränderte sich die Si‐Partikelgröße als Funktion des Verhältnisses von Si‐Vorstufe zu Reduktionsmittel . Die höchste erreichte Partikelgröße betrug 27±4.8 nm durch die SiCl 4 ‐Reduktion mit Kaliumnaphthalid.…”