Defect-rich ZnO quantum dots as a potential multifunctional sunscreen and cosmetic active ingredient

2015 ◽  
Vol 87 (9-10) ◽  
pp. 971-977 ◽  
Author(s):  
Adersh Asok ◽  
Ajit R. Kulkarni ◽  
Mayuri N. Gandhi
Keyword(s):  
Quantum Dots ◽  
Active Ingredient ◽  
Visible Region ◽  
Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Zno Nps ◽  
Visible Luminescence ◽  
Zno Quantum Dots ◽  
Zno Qds

AbstractIn sunscreens, ZnO nanoparticles (NPs) are used as inorganic UV filter which have a prominent band edge emission in the UVA region (~385 nm). When applied to biological surface, this highly penetrating UVA emission from ZnO NPs would enhance the generation of reactive oxygen species resulting in oxidative stress. Therefore, the elimination of this harmful UVA emission from ZnO NPs are much sought after for the development of safer sunscreens. In this paper we introduce the use of defect-rich ZnO (D-ZnO) quantum dots (QDs) as a multifunctional active ingredient in sunscreen/cosmetic application. These D-ZnO QDs make use of their defect energy levels to emit in visible region by bypassing their harmful band edge emission at UVA region. The D-ZnO QDs also showed prominent visible luminescence which matches well with the autofluorescence of in vivo human skin. Hence, this visible luminescence could be useful for camouflaging, thereby enabling its potential as a biologically safe active ingredient for both cosmetic and UV screening applications.

Enhancement of Photoluminescence from Organic and Inorganic Surface Passivated ZnS Quantum Dots

2001 ◽  
Vol 667 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Ling Xu ◽  
Mingha Li ◽  
Yi Ma ◽  
Xinfan Huang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Organic Coating ◽  
Band Edge ◽  
Band Edge Emission ◽  
Trap States ◽  
Edge Enhancement ◽  
Edge Emission ◽  
Inorganic And Organic

ABSTRACTZnS quantum dots (QDs) chemically synthesized in PVP stabilizing medium have been coated with Zn(OH)2, SiO2and polystyrene (PS) shells as inorganic and organic passivation agents. to synthesize ZnS/Zn(OH)2, ZnS/SiO2and ZnS/PS QDs. PL properties of inorganically passivated ZnS/Zn(OH)2 and ZnS/SiO2 had reported band edge enhancement of 8-10 times, while organically passivated ZnS/PS QDs exhibit tremendous enhancement of band edge emission as much as 10-15 times,. Therefore inorganic and organic coating can passivate trap states of different energies on the surface of ZnS QDs.

Structural, optical and magnetic properties of highly oriented transition metal (Mn/Co/Ni/Cu) doped ZnO thin films prepared by PLD

2012 ◽  
Vol 1454 ◽  
pp. 239-244 ◽  
Author(s):  
Arun Aravind ◽  
M.K. Jayaraj ◽  
Mukesh Kumar ◽  
Ramesh Chandra
Keyword(s):  
Thin Films ◽  
Transition Metal ◽  
Room Temperature Ferromagnetism ◽  
Visible Region ◽  
Band Edge ◽  
Zno Films ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Axis Orientation ◽  
Doped Zno

ABSTRACTZnO doped with transition metal (TM) thin films were grown by pulsed laser deposition. XRD pattern reveals that all the ZnTMO films have c-axis orientation normal to the substrate. The reciprocal space mapping shows that the crystallinity of ZnTMO film deteriorates at higher doping of TM. All the TM doped ZnO films have transmittance greater than 75% in the visible region. The band gap of the ZnTMO thin films shows red shift on doping with Ni and Cu where as blue shift is observed for Co and Mn which increases with TM concentration. The copper doped ZnO thin film shows green PL emission at 542 nm along with the band edge emission at 385 nm. But other TM doping shows only band edge emission (385nm) and its intensity decreases at higher doping percentage. The presence of non-polar E2high and E2lowRaman modes in thin films indicates that ‘TM’ doping do not alter the wurtzite structure of ZnO. The magnetic studies of the TM doped ZnO shows room temperature ferromagnetism

Enhancement of Band Edge Emission from ZnS/Zn(OH) 2 Quantum Dots

2001 ◽  
Vol 18 (4) ◽  
pp. 616-618 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Xu Ling ◽  
Huang Xin-Fan ◽  
Li Ming-Hai ◽  
Chen Kun-Ji
Keyword(s):  
Quantum Dots ◽  
Band Edge ◽  
Band Edge Emission ◽  
Edge Emission

Formation and Optical Properties of ZnSe Self-Assembled Quantum Dots in Cl-Doped ZnSe Thin Films Grown on GaAs (100) Substrates

2007 ◽  
Vol 124-126 ◽  
pp. 567-570
Author(s):  
G.N. Panin ◽  
H.J. Kim ◽  
S.Y. Kim ◽  
J.H. Jung ◽  
Tae Whan Kim ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Confinement Effect ◽  
Blue Shift ◽  
Emission Peak ◽  
Band Edge ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Acceptor Pair ◽  
Small Quantum

The high-resolution scanning electron microscopy (HRSEM) image showed that selfassembled ZnSe small quantum dots (QDs) and large nanodots with a pyramid shape were formed in the Cl-doped ZnSe epilayers grown on GaAs (100) substrates. The formation of the ZnSe QDs was attributed to three-dimensional growth controlled by distribution of the impurities in the Cldoped ZnSe epilayrs. Cathodoluminescence (CL) measurements at room temperature revealed the emission peak at 3.1 eV corresponding to the blue shift approximately 400 meV from the near band edge emission of 2.7 eV in the bulk ZnSe. The blue shifted CL peak indicates the quantum confinement effect resulting from the formation of the ZnSe QDs in the Cl-doped ZnSe thin film. While the peak position of the donor-acceptor pair emission shifted to higher energies with decreasing temperature, the band-edge emission peak for the QDs did not significantly change.

Binary and Ternary Mercury Chalcogenide Quantum Dots and Clusters

2002 ◽  
Vol 737 ◽  
Author(s):  
Masaru Kuno ◽  
Keith A. Higginson ◽  
Syed B. Qadri ◽  
Mohammad Yousuf ◽  
Benjamin L. Davis ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Phase Separation ◽  
Near Infrared ◽  
Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
High Quality ◽  
Synthetic Strategy ◽  
Simultaneous Use

ABSTRACTThis paper describes the synthesis, characterization and optical properties of binary and ternary mercury chalcogenide quantum dots and clusters. Such materials were made by applying a synthetic strategy involving the simultaneous use of strong Hg(II) coordinating ligands and the explicit phase separation of both metal and chalcogen precursors. High quality QDs and clusters are obtained in this manner with sharply structured absorption and band edge emission covering the visible to near infrared.

(Keynote) Band-Edge Emission from AgInS2/Ga2S3 Core/Shell Quantum Dots and Enhancement of Their Quantum Yield

2020 ◽  
Vol MA2020-02 (61) ◽  
pp. 3076-3076
Author(s):  
Susumu Kuwabata ◽  
Taro Uematsu ◽  
Watcharaporn Hoisang ◽  
Tsukasa Torimoto
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
Band Edge ◽  
Core Shell ◽  
Band Edge Emission ◽  
Edge Emission

The Enhancement of Band Edge Emission from ZnS/Zn(OH)2 Quantum Dots

2000 ◽  
Vol 642 ◽  
Author(s):  
Hatim Mohamed El-Khair ◽  
Ling Xu ◽  
Xinfan Huang ◽  
Minghai Li ◽  
Xiaofeng Gu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Surface Passivation ◽  
Band Edge ◽  
Band Edge Emission ◽  
Trap States ◽  
Edge Emission ◽  
Surface Trap ◽  
Quantum Size ◽  
Transmission Electron

ABSTRACTWurtzite structure monodisperse ZnS quantum dots (QDs) of 1 to 5 nm diameter, synthesized by colloidal chemical method, were confirmed by transmission electron microscopy (TEM) images and electron diffraction (ED) patterns. Enhanced blue shifted band edge emission from Zn(OH)2 capped ZnS QDs with decreasing size has been observed, which indicates the role of inorganic surface passivation and hence supports the quantum size effect. Detectable far-red shifted emission from bare ZnS QDs has been observed when QDs precursors and stabilizer dispersed in solvents with different polarities. This emission is attributed to the surface trap states of different energies.

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