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| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Nowshad Amin, Prof. Dr. | |
| dc.contributor.author | Yulisa Mohd Yusoff (P68194) | |
| dc.date.accessioned | 2023-10-11T02:28:18Z | - |
| dc.date.available | 2023-10-11T02:28:18Z | - |
| dc.date.issued | 2018-07-06 | |
| dc.identifier.other | ukmvital:121881 | |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/487066 | - |
| dc.description | Copper-Indium-Gallium-Selenium (CIGS) solar cells are one of the most prominent 2nd generation thin-film solar cells where the absorber layer is made up of copper based chalcopyrite materials having different concentrations of Indium, Gallium, Sulfur and Selenium. Along with the fact that all variations of CIGS films are direct bandgap semiconductor materials, CIGS solar cells can be tuned to absorb most of the solar spectrum incident on the surface of the earth. The incorporation of approximately 50 nm cadmium sulfide (CdS) layer (also called buffer layer) deposited by chemical bath deposition (CBD) process as the n-type heterojunction partner of the CIGS absorber propelled the photovoltaic conversion efficiency of devices to slightly more than 20%. In practice, CdS thin films produced by relatively low-cost CBD technique is pin-hole free, densely homogeneous and possess superior optoelectronic qualities, which is quite comparable to films produced using far costlier deposition methods, e.g. sputtering. The method is also adaptable for large area deposition. However, the CBD process generates large amounts of highly toxic chemical waste. Therefore, active research is being carried out to replace this CdS layer with cadmium free alternatives in order to reduce the use of this carcinogenic substance. Among the Cd-free alternatives under active study, zinc sulfide (ZnS) has emerged as a strong contender as it has higher absorbance of shorter wavelength photons due to its bandgap of 3.5 eV (CdS has a bandgap of 2.3 eV). Even though zinc is less toxic compared to cadmium, the CBD process used still generates large amounts of chemical waste. Moreover, the rate of the chemical reaction process needed to deposit ZnS films is also much slower than for CdS. Thus, a novel technique adapted from Metal-Organic Chemical Vapor Deposition (MOCVD) process has been developed in this study, utilizing easily attainable and inexpensive apparatus. This technique is named as modified Atmospheric Pressure Chemical Vapor Deposition (APCVD) because it eliminates the need for expensive and complicated chemical vapor deposition reactors. Various thin film characterizations have been carried out on the CdS, ZnS and CdZnS thin films produced using this modified APCVD technique, at substrate temperatures ranging from 400 to 480 C, and it was observed that the quality of the films rivaled those produced using CBD. Ultraviolet to visible (UV-Vis) wavelength Spectroscopy measurement showed transmittance of over 70% in the spectra region between 300 to 800 nm for all deposited films. Meanwhile, the calculated bandgap for CdS films ranges from 2.56 and 2.86 eV, between 2.69 and 2.86 eV for CdZnS films, and between 3.52 and 3.72 eV for ZnS films. X-ray Diffraction (XRD) and Atomic Force Microscopy (AFM) analyses revealed that the deposited films are polycrystalline in nature and were observed to provide good coverage with low occurrence of pin holes. All these chalcogen based thin films were incorporated to simple CIGS cell structures and photovoltaic effect with limited performance was confirmed. Rigorous optimization on each layers as well as interfaces between two subsequent layers is needed to achieve the highest potential to prove the applicability of these chalcogen based buffer layers in thin film solar cells such as CIGS and others.,Ph.D | |
| dc.language.iso | eng | |
| dc.publisher | UKM, Bangi | |
| dc.relation | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
| dc.rights | UKM | |
| dc.subject | Solar cells | |
| dc.subject | Thin films | |
| dc.subject | Universiti Kebangsaan Malaysia -- Dissertations | |
| dc.subject | Dissertations, Academic -- Malaysia | |
| dc.title | Cadmium and zinc based chalcogenide thin film buffer layers by atmospheric pressure chemical vapor deposition technique for cigs thin-film solar cells | |
| dc.type | Theses | |
| dc.format.pages | 182 | |
| dc.identifier.callno | TK2960.Y835 2018 3 tesis | |
| dc.identifier.barcode | 005519(2021)(PL2) | |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina | |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_121881+SOURCE1+SOURCE1.0.PDF Restricted Access | 5.45 MB | Adobe PDF |  View/Open |
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