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https://ptsldigital.ukm.my/jspui/handle/123456789/519619| Title: | Transition metal dichalcogenide MoS2 based alternative absorbers for cost effective photovoltaic applications |
| Authors: | Haroon Rashid (P70489) |
| Supervisor: | Nowshad Amin, Prof. Dr. |
| Keywords: | Absorbers Photovoltaic power systems |
| Issue Date: | 27-Dec-2017 |
| Description: | Two-dimensional transition metal dichalcogenide (TMDC) materials i.e. MoS2, WS2, WSe, etc. have shown good prospects of tunable bandgap to be utilized in low cost fabrication of solar photovoltaic (PV). Among all, Molybdenum Disulfide (MoS2) is recognized to be potential low cost and highly earth abundant alternative sunlight harvester for a possible replacement of the conventional photovoltaic materials in visible range. It is a suitable photovoltaic absorber material mainly due to its optimum optical and electrical properties with large absorption coefficients of 105 cm-1. It has an indirect band gap of 1.29 eV, while the direct transition starts at 1.6 eV. Numerically, a hetero-junction device structure of Mo/p-MoS2/n-CdS/n-ZnO has been analysed by 1D-Solar Cell Capacitance Simulator (SCAPS) that predicts the conversion efficiency over 19%. The analysis includes the device stability at various operating temperature. In practice, various thin films have been grown on top of soda lime glass (SLG) to investigate several growth parameters such as deposition power and operating pressure effects on MoS2 layer with the aim to establish a base line fabrication process. To validate semiconducting nature of MoS2, dark current was found in the range of 0.05 A to 0.3 A for voltage of 0.5 V to 1.0 V from dark current-voltage measurements. Films grown at deposition power of 100 W under argon flow rate of 3.5 SCCM unveiled smooth morphology with average surface roughness of 1.83 nm, denser microstructure and crystalline in nature with hexagonal crystal structure of peaks corresponding to (100) and (110) along with reflection planes at 33.0� and 59.2�, respectively. These optimum parameters were used to achieve MoS2 layer and subsequently sulfurized with different timing profiles at working pressure of 370 torr at room temperature. Sulfurization process time was varied from 60 minutes to 150 minutes with the aim to investigate the evolution of MoS2 crystallography, phase as well as elemental composition variation. Sulfurization improves the crystallinity of MoS2 thin films as evident from the X-Ray Diffraction (XRD) and Field Effect Scanning Electron Microscope (FESEM) analysis. Conversely, prominent grain coalescence only occurs when sulfurized for 150 minutes. Segregation of Sulfur rich compound on top of MoS2 film has been observed from FESEM characterization and confirmed by Energy Dispersive X-ray spectroscopy (EDX) measurement for almost all sulfurized films. The detailed structural, morphological and optical characterizations were investigated using XRD, Atomic Force Microscopy (AFM), FESEM, EDX and Ultraviolet-Visible Spectroscopy (UV-Vis). Preliminary MoS2 based solar cell device was fabricated at optimized parameters with the structure of SLG/Mo/p-MoS2/n-CdS/n-ZnO/ITO/Al, instituting the speculative validation of this study.,Ph.D. |
| Pages: | 138 |
| Call Number: | TK1087.R347 2017 3 tesis |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina |
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