Recycling of CIGS flexible solar cells: Investigation of organic acids leaching

Abstract

The Photovoltaic market has been rising sharply in recent years and is expected to grow steadily in the upcoming years. The copper-indium-gallium diselenide (CIGS) solar cell has become a more and more significant role in the photovoltaic industry, and its application in the second generation of solar cells has increased in recent years, which means photovoltaic waste will be prominent in the future. To reduce resource consumption and recycle valuable materials from an economical and environmental perspective, further research on metal recovery should be carried out. Currently, from an economic point of view, recycling CIGS solar cells is not feasible on an industrial scale, and research is limited. The current end-of-life module recycling is done using thermal decomposition, pyrolysis treatment, and dry etching in the presence of Chlorine gas at high temperatures, which could require high energy demand and high effort for the purification of metals. Moreover, due to the drawbacks of inorganic acid leaching, such as toxic gas production and low selectivity of the metals. The viability of organic acids as an alternative leaching agent needs to be investigated. The project aims to extract the valuable metals present in CIGS solar cells by comprehending the influence of leaching variables through utilizing organic acids in an environmentally friendly way. Citric acid and tartaric acid were employed for the leaching process, as well as nitric acid leaching was studied to compare the results. Some leaching conditions such as concentration, surface area to liquid ratio, temperature, and agitation method are considered to find the optimum condition for the metal recovery from CIGS solar cells. The results show that different division methods have an impact on extracting silver with nitric acid. The mass of silver in the whole solar cell is 44% more than in the divided cell sample. For 1M citric acid with a surface area to liquid ratio of 1:3 cm2/ml, temperature of 50◦C and 100 rpm stirring speed, a high selectivity of Zn and In at 8 hours was observed.