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Title:	Fabrication of copper-tin-sulphide thin film solar cells by sequential-sputtering technique
Authors:	Ejarder Sabbir Hossain (P85754)
Supervisor:	Badariah Bais, Assoc. Prof. Dr.
Keywords:	Thin films Solar cells Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	25-Feb-2019
Description:	Copper-tin-sulphide (CTS) thin film solar cell has attracted vast research interest due to its earth-abundant and non-toxicity features. CTS has similar crystal structure as copper-zinc-tin-sulphide (CZTS) and has been considered as a prospective candidate for chalcogenide based absorber. Up to date, the best efficient CTS based solar cell was fabricated using co-evaporation technique with 4.63% conversion efficiency. However, in terms of composition control, and smooth large-scale production capability, sputtering is the best deposition method. CTS thin film solar cell can be fabricated by depositing either sulphur based precursor or metallic precursor through sputtering method. Sulphur based precursor are responsible for the MoS2 layer in between Mo and absorber layers, which deteriorates the cell performances. Metallic precursor can prohibit the formation of MoS2, however it suffers lots of problems, such as, secondary phases, voids, pinholes and unfavourable morphology which are the main challenges to improve the efficiency. In this study, sequential sputtering deposition of CuSn(CT)/Sn layers were carried out to determine the optimum Cu/Sn ratio for pinhole and void free smooth surface. Special emphasize was given on the optimization of the sulphurization parameters such as temperature, duration and pressure to improve the CTS thin film crystallinity and grain size. The influences of as-deposited Cu/Sn ratio as well as the sulphurization parameters on CTS thin films were characterized through X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive Xray spectroscopy (EDX), ultraviolet-visible (UV-Vis) spectroscopy and Hall effect measurement system. Overall, 12 CTS full photovoltaic devices were fabricated in the configuration of Mo/CTS/CdS/ZnO/ITO/Ag structure and measured by standard Light Current Voltage (LIV) tester. The as deposited Cu/Sn ratio was varied from 1.56 to 0.91 for Sn deposition time varying from 10 min to 50 min. Preliminary fabricated CTS thin films showed monoclinic phase with (-131) preferential orientation for the optimized Cu/Sn ratio of 1.09. The same film demonstrated the lowest surface roughness of 170.06 nm and the highest optical band gap of 0.90 eV. A preliminary full cell as the best test case was able to achieve the conversion efficiency of 0.71%. The optimal sulphurization temperature, duration and pressure were found to be 580 °C, 3 hr and 200 Torr, respectively. Results show a gradual enhancement of both CTS thin films properties and solar cell devices performances with increased temperature and time. A medium sulphurization pressure was found to be beneficial for CTS thin films and devices. The optimized CTS thin films showed the same monoclinic phase with the crystallite size of 83.37 nm. Stone-like grain shaped thin film was achieved with an average grain size in micrometre range. The optimised CTS device demonstrated the highest conversion efficiency of 0.96% with the performance parameters of Voc = 0.147 V, Jsc = 19.08 mA/cm2 and FF = 0.34.,Ph.D.
Pages:	134
Call Number:	TA418.9.T45H567 2019 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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