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Synthesis of cadmium-free quantum dots

Due to the toxicity issues of cadmium-based quantum dots, there is a need to replace it with cadmium-free quantum dots. In this project, synthesis of zinc selenide quantum dots (ZnSe QD) using hot injection method will be studied. In today’s researches, diethylzinc is used as the zinc precursor. How...

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Main Author: Aaron, Tan Cheng Shiong
Format: Monograph
Language:English
Published: Universiti Sains Malaysia 2017
Subjects:
T Technology
TA401-492 Materials of engineering and construction. Mechanics of materials
Online Access:http://eprints.usm.my/52804/1/Synthesis%20of%20cadmium-free%20quantum%20dots_Aaron%20Tan%20Cheng%20Shiong.pdf
http://eprints.usm.my/52804/
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spelling my.usm.eprints.52804 http://eprints.usm.my/52804/ Synthesis of cadmium-free quantum dots Aaron, Tan Cheng Shiong T Technology TA401-492 Materials of engineering and construction. Mechanics of materials Due to the toxicity issues of cadmium-based quantum dots, there is a need to replace it with cadmium-free quantum dots. In this project, synthesis of zinc selenide quantum dots (ZnSe QD) using hot injection method will be studied. In today’s researches, diethylzinc is used as the zinc precursor. However, diethylzinc possess safety issues in which it reacts violently with water and easily ignites upon contact with air. Therefore, a new material (zinc acetate) was proposed in this project. The precursors were prepared by dissolving zinc acetate and selenium into trioctylphosphine (TOP). They were then injected into two different types of coordinating solvents, that were mixture of trioctylphosphine oxide (TOPO), hexadecylamine (HDA) and tetradecylphosphonic acid (TDPA), and hexadecylamine (HDA) only. Synthesis of ZnSe QD in HDA coordinating solvent was found to be successful. Growth time and molar ratio (Zn:Se) were manipulated to determine the optimum parameters. The optimum parameters to synthesize ZnSe QD were at molar ratio (Zn:Se) of 1:2 and growth time of 15 minutes. Based on the UV-Vis absorbance spectra, the radius of ZnSe QD was calculated by using effective mass approximation and was found to be 3.61 nm in which, it is smaller than the bulk exciton Bohr radius of ZnSe (5.7 nm). Stability study on ZnSe QD showed that the ZnSe QD was stable and did not agglomerate much throughout one month period. The UV-Vis absorption spectra remained at 431 nm throughout the month, indicating that there were no changes in the particle size. Based on zeta potential measurement, ZnSe QD were found to agglomerate (unstable) at first (11.5 mV) and became stable over period of time (-21.1 mV). In conclusion, synthesis of ZnSe QD using zinc acetate as Zn precursor with HDA coordinating solvent was successful. Universiti Sains Malaysia 2017-06-01 Monograph NonPeerReviewed application/pdf en http://eprints.usm.my/52804/1/Synthesis%20of%20cadmium-free%20quantum%20dots_Aaron%20Tan%20Cheng%20Shiong.pdf Aaron, Tan Cheng Shiong (2017) Synthesis of cadmium-free quantum dots. Project Report. Universiti Sains Malaysia, Pusat Pengajian Kejuruteraan Bahan Sumber Mineral. (Submitted)
institution Universiti Sains Malaysia
building Hamzah Sendut Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Sains Malaysia
content_source USM Institutional Repository
url_provider http://eprints.usm.my/
language English
topic T Technology
TA401-492 Materials of engineering and construction. Mechanics of materials
spellingShingle T Technology
TA401-492 Materials of engineering and construction. Mechanics of materials
Aaron, Tan Cheng Shiong
Synthesis of cadmium-free quantum dots
description Due to the toxicity issues of cadmium-based quantum dots, there is a need to replace it with cadmium-free quantum dots. In this project, synthesis of zinc selenide quantum dots (ZnSe QD) using hot injection method will be studied. In today’s researches, diethylzinc is used as the zinc precursor. However, diethylzinc possess safety issues in which it reacts violently with water and easily ignites upon contact with air. Therefore, a new material (zinc acetate) was proposed in this project. The precursors were prepared by dissolving zinc acetate and selenium into trioctylphosphine (TOP). They were then injected into two different types of coordinating solvents, that were mixture of trioctylphosphine oxide (TOPO), hexadecylamine (HDA) and tetradecylphosphonic acid (TDPA), and hexadecylamine (HDA) only. Synthesis of ZnSe QD in HDA coordinating solvent was found to be successful. Growth time and molar ratio (Zn:Se) were manipulated to determine the optimum parameters. The optimum parameters to synthesize ZnSe QD were at molar ratio (Zn:Se) of 1:2 and growth time of 15 minutes. Based on the UV-Vis absorbance spectra, the radius of ZnSe QD was calculated by using effective mass approximation and was found to be 3.61 nm in which, it is smaller than the bulk exciton Bohr radius of ZnSe (5.7 nm). Stability study on ZnSe QD showed that the ZnSe QD was stable and did not agglomerate much throughout one month period. The UV-Vis absorption spectra remained at 431 nm throughout the month, indicating that there were no changes in the particle size. Based on zeta potential measurement, ZnSe QD were found to agglomerate (unstable) at first (11.5 mV) and became stable over period of time (-21.1 mV). In conclusion, synthesis of ZnSe QD using zinc acetate as Zn precursor with HDA coordinating solvent was successful.
format Monograph
author Aaron, Tan Cheng Shiong
author_facet Aaron, Tan Cheng Shiong
author_sort Aaron, Tan Cheng Shiong
title Synthesis of cadmium-free quantum dots
title_short Synthesis of cadmium-free quantum dots
title_full Synthesis of cadmium-free quantum dots
title_fullStr Synthesis of cadmium-free quantum dots
title_full_unstemmed Synthesis of cadmium-free quantum dots
title_sort synthesis of cadmium-free quantum dots
publisher Universiti Sains Malaysia
publishDate 2017
url http://eprints.usm.my/52804/1/Synthesis%20of%20cadmium-free%20quantum%20dots_Aaron%20Tan%20Cheng%20Shiong.pdf
http://eprints.usm.my/52804/
_version_ 1735387508546469888
score 13.251813

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