Impact of co-doped cation substitution on kesterite based Cu2ZnSnS4 photo absorber layer via solution based sol-gel method for sustainable photovoltaic application

The thin-film photovoltaic (PV) technology is a potential candidates for harvesting electrical energy from the solar spectrum, although much research and development is still necessary. Currently, crystalline silicon (c-Si) is regarded as a significant resource in thin-film PV technology and dominates a significant portion of the photovoltaic market. The c-Si industry continues to struggle despite the introduction of numerous new technologies due to high production and processing costs. Due to the limitations of the c-Si solar cell, alternative solar energy materials with high device performance, low production costs, and environmental tolerance must be explored. Chalcogenide (CIGS) and kesterite (CZTS) solar cell materials are highly considered to overcome c-Si technology's constraints because of their wide solar spectrum absorption, adjustable band gap property, low production cost, and roll-to-roll manufacturing process. But for the CIGS case, because of the cost of gallium (Ga) and indium (In), the fabrication process became more expensive. However, the abundant nature of copper, zinc, tin, and sulfur elements makes the kesterite materials more reliable and the roll-to-roll fabrication approach easy. Although some issues result from a number of difficulties for CZTS materials. The formation of possible secondary phases like as  (ZnS and SnS), which lower absorber quality and restrict device efficiency; short carrier lifetimes, frequently brought on by poor crystallinity and high defect densities; and a shortage in open-circuit voltage (Voc) are all results of deep-level defects and grain boundary recombination. The maximum output efficiency of CZTS-solar cells has been reported to be around 12.6%. Doping with cation elements such as Li, Na, K, Rb, and Cs has emerged as a viable approach to get over this kind of hurdle in recent years. Cation incorporation has been shown in experiments to passivate grain boundaries, decrease defects, improve crystallinity, and encourage grain growth. They also improve band alignment, lower VOC deficit, and lengthen carrier lifetimes. Several systematic characterizations using XRD, SEM, and AFM will be used to characterize cation substitution photo-absorber films' structural, optical, and morphological properties systematically throughout the process to optimize for efficient PV application. 

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