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Title:	Fabrication of copper-zinc-tin sulphide thin film solar cell by single quaternary compound target in radio frequency magnetron sputtering
Authors:	Mohammad Tanvirul Ferdaous (P83767)
Supervisor:	Nowshad Amin, Prof. Dr.
Keywords:	Solar cells Copper-zinc alloys Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	19-Sep-2018
Description:	Copper-Zinc-Tin-Sulphide (CZTS) based thin film solar cells are promising 2nd generation solar cells due to abundance and non-toxic nature of their constituent elements. To date, laboratory scale CdS/CZTS heterojunction thin film solar cell has recorded the highest conversion efficiency of 9.1% via multi-target sequential sputtering process, which is expensive and time consuming from industrial point of view. Hence, this study focuses primarily on the deposition and characterization of CZTS thin film absorber layer by single quaternary compound target in RF sputtering method. The highest conversion efficiency achieved to-date by this simpler method is 6.94%, which has potential for improvement. Apart from investigating core absorber layer by a simpler process, major emphasize is also given to charge collection efficiency at two contact ends namely Mo/CTZS interfacial region and transparent conductive oxide (TCO) layer. AMPS 1D software was employed as numerical simulation software while DC and RF sputtering, thermal annealing, chemical bath deposition (CBD) were few of the methods employed for the experimental works. Computer aided numerical simulation reveals that the n-MoS2 interfacial layer which can form spontaneously due to the reaction between Mo and CZTS layers is detrimental to the CZTS solar cell devices compared to p-MoS2. The degree of degradation induced by n-MoS2 depends on its physical and electrical properties such as thickness, band-gap energy, electron affinity and carrier concentration. Fabrication related experimental studies reveal that compositional property of as-sputtered CZTS, mainly the preferential Cu-poor and Znrich off-stoichiometry is influenced by the sputtering process parameters such as RF power, substrate temperature, operating pressure, target-sample distance as evident from the EDX analysis. In particular, high RF power was found to be detrimental with Cu loss as high as 53% from the original atomic composition for a particular investigated target. Operating pressure and target-sample throw distance also contributed to compositional deviation owing to induced preferential elemental loss. Sulphurization process with appropriate duration was found to smoothen the compositional deviation of CZTS thin films. Ga doped ZnO (GZO) was implemented as TCO to replace expensive and scarce ITO by DC sputtering with emphasis on process parameters like deposition power and temperature. Improvement in desirable electrical and optical properties along with spatial uniformity of deposited GZO films were linked to certain process parameters and crystallographic properties of deposited films. GZO thin films exhibited resistivity of ~1x10-3 Ω.cm and optical transparency of ~90% in the visible spectrum validating its suitability as a promising TCO layer. CZTS solar cell device fabrication at the optimized temperature of 560 ˚C for 60 minutes during sulphurization achieved the photovoltaic conversion efficiency of 1.605 % for an active area of 0.25 cm2 with Voc = 588 mV, Jsc = 9.504 mA/ cm2 and FF = 28.74 %, establishing the conceptual validation of this study.,Ph.D.
Pages:	146
Call Number:	TK2960.M84786 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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