الفهرس 
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Abstract
Cu2ZnSnS4 (CZTS) and (Cu2ZnSn (SxSe1-x)4 CZTSSe kesterite compounds have potential properties for low-cost thin-film solar cells. It is made up of abundant elements as well as non-toxic material, and it has desirable properties for thin film photovoltaic (PV) applications, such as a high absorption coefficient of close to 10-4 cm-1 and a band gap of 1.5 and 1.25 eV for CZTS and CZTSSe, respectively. Spray pyrolysis was used to successfully produce CZTS to obtain high-quality CZTS thin films at different deposition temperatures (350, 375, 400 oC), CZTS water-based precursors were deposited onto clean glass (SLG) and Molybdenum (Mo) substrates at optimum deposition parameters. Investigating the effect of annealing processes in chalcogen atmospheres (S, Sn) for sulfurization and (Se and SnSe) for selenization at 530 oC for 30 minutes on crystal structure, composition, morphology, and band gap. The average crystallite size of as-deposited CZTS thin films is 9.42 nm, 10.30 nm, and 11.07 nm. It was also found that the size of crystallite increases with annealing to be 54.64, 51.23, and 48.16 nm for films deposited at 350, 375, and 400 oC, respectively. Raman measurements
confirmed that the main peaks of CZTS for various fabrication conditions
were at 337 cm-1, which corresponds to the A1 mode of single phase CZTS, and two dominant Raman peaks were observed and assigned to A symmetry modes: CZTSe -like (165-205 cm-1). where the main peaks for thin films after annealing become narrower and sharper than as-deposited, indicating crystallinity improvement. Moreover, the SEM measurements confirm that annealing improved the surface morphology and resulted in a densified and large grain structure, which improves device performance. The average diameter grain size of CZTS thin films determined by ImageJ increases with increasing deposition temperature and was found to be within the range of ” ” ” " ~ " ” ” ” 536.5, 554, and 636.5 nm for 350, 375, and 400 ℃, respectively. In addition, cross-section images for the absorbers show an increase in CZTS thickness from 1.1 m to 1.16 m for annealed CZTSSe films. The compositional ratios of CZTS were confirmed by EDX found to be Cu/(Zn + Sn) ratio was found to
be 0.9, 1.2, and 0.9 after 30 minutes of annealing at 530 °C, and the Zn/Sn ratio was found to be 1.06, 1.00, and 1.2 at 350, 375, and 400 °C, respectively and annealed CZTSSe sample has a Cu/(Zn+Sn) ratio of 0.95 and a Zn/Sn ratio of 1.27. Furthermore, the results confirm the overlapping of Mo and S lines, The EDX measurements confirmed the uniform distribution of all elements. This means that the Mo and S elements are evenly distributed throughout the sample, rather than being concentrated in certain areas or regions. Therefore, it can be concluded that the sample contains both Mo and S and that these elements are uniformly distributed throughout the sample. Finally, the band gaps of annealed samples were found to be 1.5 and 1.25 for CZTS and CZTSSe, respectively. According to the results, the best conditions for synthesizing high quilty CZTS and CZTSSe absorbers layers by spray pyrolysis are spraying the samples at Mo substrate for 30 minutes at 400 °C, then annealing for 30 minutes at 530 °C in (S, Sn) for sulfurization and (Se and SnSe) for selenization. This gives Cu-poor and Zn-rich composition structures for high-performance solar cells. A thin layer of CdS was deposited on the optimum absorber layer of SLG/Mo/CZTS prepared by normal chemical bath deposition (CBD) and laser-assisted chemical bath deposition (LACBD) by in-situ irradiation of the bath with a diode-pumped solid-state (DPSS) at 532 nm with laser power estimated was 24 mW and the laser fluence ” ” ” " ~ " ” ” ” 75 mJ/cm2. A comparison of samples grown by laser-assisted and standard chemical bath deposition was performed. The results showed that the thickness of CdS thin films grown in a laser-irradiated bath was 90 nm greater than that of CBD-formed films at 60 nm. This implied that the additional
photon energy supplied by the laser radiation accelerated film growth, which is suitable for solar cell devices. The i-ZnO window layers with a thickness of around 50 nm were sputtered on top of CdS. The CZTS and CZTSSe devices were finished with a sputtered ZnO: Al (500 nm) layer. The samples’ I-V curves were measured in both the dark and under illumination using a solar simulator (AM 1.5 G irradiation, 1000 W/m2). The well-established CZTS device with ideal nanostructure (SLG / Mo / CZTS / CdS / IZnO / AZnO) shows the Voc and Isc were 199.33 mV and 12.17 mA/cm2, respectively. The fill factor and efficiency of the device were 37.65% and 0.91%, respectively. As a result, the CZTSSe solar cell sample achieved the best PV performance with an open-circuit voltage (Voc) of 298 mV, a short-circuit current density (Jsc) of 14.5 mA/ cm2, a fill factor (FF) of 40 ٪, and a η value of 1.7 ٪ was achieved in the CZTSSe solar cell sample. The thesis has shown that PV devices can be manufactured and has confirmed some parameters for optimizing this process. This work has identified many issues that require further investigation, and some recommendations for future work are made here. Different chemical precursors and solvents, as well as optimizing deposition techniques, including the drying process, are used to produce uniform, high-quality films. Controlling the composition of the final CZTS device requires better understanding. Controlling interface reactions between Mo/CZTS and CZTS/CdS layers requires more research into their properties and their effects on CZTS device performance. The effects of secondary phase passivation and element diffusion between layers using ultra-thin intermediate layers between the layers Mo/CZTS/CdS on CZTS device performance would also be studied.