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Fabrication of Ⅱ-Ⅳ-Ⅴ2 colloidal quantum dots : CdSnP2, CdSnAs2
- Author(s)
- 이성희
- Alternative Author(s)
- Sunghee Lee
- Advisor
- 김상욱
- Department
- 일반대학원 분자과학기술학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2015-08
- Language
- eng
- Keyword
- Ⅱ-Ⅳ-Ⅴ2; colloidal quantum dot
- Alternative Abstract
- N-type CdSnP2(CTP) with the chalcopyrite structure, one of the Ⅱ-Ⅳ-Ⅴ2 semiconductor materials, has been known to optimal materials for solar energy conversion owing to direct 1.17eV band gap, large absorption coefficient (>104cm-1) and fast electron mobility (>1015cm-3). Another candidates P-type CdSnAs2 crystals, having the tetragonal chalcopyrite structure, was reported a narrow direct band gap (0.26 eV) material and one of the highest electron mobility(104 cm2 V-1 sec-1) among a ternary compounds. The Ⅱ-Ⅳ-Ⅴ2 family showed similar structure with Ⅲ-Ⅴ family however interesting physical properties by tetragonal unit cell anisotropic distortion. Unfortunately, they are only developed by physical single crystal growth method for photoelectrical analysis and theoretically calculation regions. In here, we synthese the Ⅱ-Ⅳ-Ⅴ2 CTP and CTA quantum dots(QDs) for the first time by hot-injection colloidal methods and investigated their physical and chemical properties. Their chalcopyrite crystal structure were confirmed by X-Ray diffraction(XRD) analysis. The broad full width at half maximum(FWHM) of diffraction peaks were observed due to the size of nanocrystalline. Also zinc blende ZnS was used as inorganic passivation materials by epitaxial growth therefore core-shell structure of CTP and CTA improved photoluminecence property and confirmed by peak shift in XRD data and transmission electron microscopy(TEM) images. CTP and CTA QDs have the size of 4 nm, which was observed by high resolution ? transmission electron microscopy(HR-TEM), energy dispersive x-ray(EDX) mapping proved the existence of cadmium, tin and phosphorous or arsenide, qualitatively. For more precise quantitative composition analysis, inductively inductively coupled plasma-optical emission spectrometry(ICP-OES) analysis was conducted. As a result, the ratio of the elements is observed; Cd:Sn:P=0.9 :1.5 :2, Cd:Sn:As=0.95 :1.05 :2. Through Absorption and Emission spectroscopy, CTP shows absorption of 670 nm in vis-NIR region and CTA shows absorption of 1190 nm in NIR region. Finally, for the application, cyclovoltammetry (CV) were measured which HOMO and LUMO band position and band gap; CTP (- 5.13 eV, 3.53 eV, 1.6 eV) and CTA (- 3.63 eV, -4.88 eV, 1.25eV), respectively. CTP, CTA QDs tried to apply as absorber materials in mesoporous TiO2 matrix, however it has problems in device cell fabrication. Therefore photo-conversion efficiency will be reported in further study.
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Molecular Science and Technology > 3. Theses(Master)
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