scholarly journals Interparticle Spacing Effect among Quantum Dots with High-Pressure Regulation

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 325
Author(s):  
Ji-Chao Cheng ◽  
Ling-Yun Pan ◽  
Xiao-Li Huang ◽  
Yan-Ping Huang ◽  
Ying-Hui Wang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Pressure ◽  
Optical Properties ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Spacing Effect ◽  
Transient State ◽  
Interparticle Spacing ◽  
Pressure Regulation ◽  
Volume Compression

In this paper, we explore whether interparticle spacing affects steady-state and transient-state optical properties by comparing close-packed CdSe/ZnS–quantum dots (QDs) and CdSe/ZnS–QDs dispersed in polymethyl methacrylate (PMMA). High–pressure is an effective physical means to adjust the interparticle spacing of QDs, which may artificially expand the application of QDs further. The results under high–pressure indicate that it is the reduced interparticle spacing rather than the enhanced quantum confinement effect with volume compression that has a stronger effect on exciton relaxation of CdSe/ZnS–QDs. This work is hoped to help us further understand the effect of interparticle spacing among QDs in various integrated environments.

scholarly journals Tailoring Blue-Green Double Emissions in Carbon Quantum Dots via Co-Doping Engineering by Competition Mechanism between Chlorine-Related States and Conjugated π-Domains

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 635 ◽  
Author(s):  
Xue Sun ◽  
Huilian Liu ◽  
Lili Yang ◽  
Xinying Wang ◽  
Weiqiang Yang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Reaction Time ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Carbon Quantum Dots ◽  
Confinement Effect ◽  
Co Doping ◽  
Photoelectric Properties ◽  
Co Doped

Representing single-layer to tens of layers of graphene in a size less than 30 nm, carbon quantum dots (CQDs) is becoming an advanced multifunctional material for its unique optical, electronic, spin and photoelectric properties induced by the quantum confinement effect and edge effect. In present work, upon co-doping engineering, nitrogen and chlorine co-doped CQDs with uniquely strong blue-green double emissions are developed via a facile and one-pot hydrothermal method. The crystalline and optical properties of CQDs have been well manipulated by tuning the mole ratio of nitrogen/chlorine and the reaction time. The characteristic green emission centered at 512 nm has been verified, originating from the chlorine-related states, the other blue emissions centered at 460 nm are attributed to the conjugated π-domain. Increasing the proportion of 1,2,4-benzentriamine dihydrochloride can effectively adjust the bandgap of CQDs, mainly caused by the synergy and competition of chlorine-related states and the conjugated π-domain. Prolonging the reaction time promotes more nitrogen and chlorine dopants incorporate into CQDs, which inhibits the growth of CQDs to reduce the average size of CQDs down to 1.5 nm, so that the quantum confinement effect dominates into play. This work not only provides a candidate with excellent optical properties for heteroatoms-doped carbon materials but also benefits to stimulate the intensive studies for co-doped carbon with chlorine as one of new dopants paradigm.

Vertical Quantum Confinement Effect on Optical Properties of Strain-Induced Quantum Dots Self-Formed in GaP/InP Short-Period Superlattices

1998 ◽  
Vol 37 (Part 1, No. 3B) ◽  
pp. 1540-1547 ◽  
Author(s):  
Seong-Jin Kim ◽  
Hajime Asahi ◽  
Kumiko Asami ◽  
Minori Takemoto ◽  
Mayuko Fudeta ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Short Period ◽  
Short Period Superlattices

Size-Controlled Microwave-Assisted Synthesis of Water-Dispersible Cd(Se,S) Quantum Dots for Potential Biological Applications

2015 ◽  
Vol 1784 ◽  
Author(s):  
E. Calderón-Ortiz ◽  
S. Bailón-Ruiz ◽  
L. Alamo-Nole ◽  
J. Rodriguez-Orengo ◽  
O. Perales-Perez
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Quantum Confinement Effect ◽  
Reactive Oxygen Species Generation ◽  
Size Control ◽  
Average Crystallite Size ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted

ABSTRACTNanomedicine is fostering significant advances in the development of platforms for early detection and treatment of diseases. Nanoparticles (NPs) like quantum dots (QDs) exhibit size-dependent optical properties for light-driven technologies, which might become important in bio-imaging, sensing and photo-dynamic therapy (PDT) applications. The present research addresses the synthesis of water-stable Cd-based QDs via a Microwave-Assisted synthesis approach using cadmium sulfate salt, and thioglycolic acid as Cd- and S-precursors, respectively. Selenide ions were available by reductive leaching of metallic Selenium in Sodium bisulfite solution. The size control and the tunability of the optical properties were achieved by a suitable control of the reaction temperature (in the 140°C- 190°C range) and reaction time (10 minutes-40 minutes). X-ray diffraction analyses suggested the development of a CdSe,S face cubic centered structure; the broadening of the diffraction peaks indicated the presence of very small nanocrystals in the samples. The average crystallite size was estimated at 5.50 nm ± 1.17nm and 3.72 nm ± 0.04 nm, for nanoparticles synthesized at 180°C after 40 minutes or 10 minutes of reaction, respectively. HRTEM images confirmed the crystalline nature and the small size of the synthesized nanocrystals. In turn, the exciton was red-shifted from 461nm to 549 nm when the reaction temperature was prolonged from 140°C to 190 °C, suggesting the crystal growth. The corresponding band gap values were approximately 2.2 eV, confirming the quantum confinement effect (bulk value 1.74eV). This red shift was also evidenced in PL measurements where the main emission peak was shifted from 507 nm to 564 nm when the samples were excited at 420 nm. A narrow size-tunable emission also was supported by the full width at half maximum (∼ 45 nm) for the synthesized nanocrystals. The reactive oxygen species generation capability of as-synthesized QDs was also investigated. The correlation between the particle size and the generation of (ROS) by the degradation of methylene blue was evident with a reduction of MB concentration from 10μM to 7.5μM and 6.7μM after 15 minutes of UV irradiation for reaction time of 10 min. and 40 min. respectively. No additional degradation was noticed after 60 minutes of irradiation.

scholarly journals Strong Quantum Confinement Effect in the Optical Properties of Ultrathin α-In2Se3

2016 ◽  
Vol 4 (12) ◽  
pp. 1939-1943 ◽  
Author(s):  
Jorge Quereda ◽  
Robert Biele ◽  
Gabino Rubio-Bollinger ◽  
Nicolás Agraït ◽  
Roberto D'Agosta ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect

Observation of quantum-confined exciton states in monolayer WS2 quantum dots by ultrafast spectroscopy

Nanoscale ◽  
2021 ◽  
Author(s):  
Shuwen Zheng ◽  
Lei Wang ◽  
Hai-yu Wang ◽  
chenyu Xu ◽  
Yang Luo ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Transition Metal ◽  
Edge Effect ◽  
Quantum Confinement ◽  
Ultrafast Spectroscopy ◽  
Photophysical Properties ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Transition Metal Dichalcogenide ◽  
Fundamental Study

Monolayer transition metal dichalcogenide quantum dots (TMDC QDs) could exhibit unique photophysical properties, because of both lateral quantum confinement effect and edge effect. However, there is little fundamental study on...

scholarly journals Quantum Confinement Effect and Photoenhancement of Photoluminescence of PbS and PbS/MnS Quantum Dots

2020 ◽  
Vol 10 (18) ◽  
pp. 6282
Author(s):  
Muhammad Safwan Zaini ◽  
Josephine Ying Chyi Liew ◽  
Shahrul Ainliah Alang Ahmad ◽  
Abdul Rahman Mohmad ◽  
Mazliana Ahmad Kamarudin
Keyword(s):  
Aqueous Solution ◽  
Quantum Dots ◽  
Quantum Confinement ◽  
Shell Thickness ◽  
Quantum Confinement Effect ◽  
Band Gap Energy ◽  
Confinement Effect ◽  
Core Shell ◽  
Lead Sulphide ◽  
Peak Energy

The quantum confinement effect and photoenhancement of photoluminescence (PL) of lead sulphide (PbS) quantum dots (QDs) and lead sulphide/manganese sulphide (PbS/MnS) core shell QDs capped with thiol ligands in aqueous solution were investigated. From PL results, the presence of MnS shells gives a strong confinement effect which translates to higher emission energy in PbS/MnS core shell QDs. Increasing MnS shell thickness from 0.3 to 1.5 monolayers (ML) causes a blueshift of PL peak energies as the charge carriers concentrated in the PbS core region. Enhancement of the PL intensity of colloidal PbS and PbS/MnS core shell QDs has been observed when the samples are illuminated above the band gap energy, under continuous irradiation for 40 min. Luminescence from PbS QDs and PbS/MnS core shell QDs can be strongly influenced by the interaction of water molecules and oxygen present in aqueous solution adsorbed on the QD surface. However, PbS/MnS core shell QDs with a shell thickness of 1.5 ML did not show a PL peak energy stability as it was redshifted after 25 min, probably due to wider size distribution of the QDs.

Properties of Nanostructure Formed on SiO2/Si Interface by Laser Radiation

2007 ◽  
Vol 131-133 ◽  
pp. 559-562 ◽  
Author(s):  
Arthur Medvid ◽  
Igor Dmitruk ◽  
Pavels Onufrijevs ◽  
Iryna Pundyk
Keyword(s):  
Optical Properties ◽  
Laser Radiation ◽  
Band Gap ◽  
Quantum Confinement ◽  
Quantum Confinement Effect ◽  
Confinement Effect ◽  
Visible Range ◽  
Pulsed Nd:Yag Laser ◽  
Self Organized ◽  
Graded Band Gap

The aim of this work is to study optical properties of Si nanohills formed on the SiO2/Si interface by the pulsed Nd:YAG laser radiation. Nanohills which are self-organized on the surface of Si, are characterized by strong photoluminescence in the visible range of spectra with long wing in the red part of spectra. This peculiarity is explained by Quantum confinement effect in nanohillsnanowires with graded diameter. We have found a new method for graded band gap semiconductor formation using an elementary semiconductor. Graded change of band gap arises due to Quantum confinement effect.

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