Mitigation of environmental toxicity in perovskite solar panels through perfluoroalkylated additives

Abstract

Most of the energy today is produced from non-renewable energy sources (fossil fuels such as coal, oil and natural gas, etc.), whose combustion generates greenhouse gases (CO2, CH4, N2O, etc.). Over the years these, especially CO2, have caused an increase in global temperature[1]. Concern for the environment and human health has pushed researchers to study new alternative sources of energy. Among these, photovoltaics is currently the most studied, thanks to the infinite availability of energy and easy access to the source. For decades, the photovoltaic market has been dominated by silicon cells, which is still the most used material despite presenting several critical issues. To this end, in the last twenty years, the attention of researchers has shifted to a photovoltaic technology that uses perovskite cells. Since their first applications in 2009[2], these cells have shown excellent characteristics to compete with those traditionally used today. With this technology it is possible to produce thin and light photovoltaic cells using cheap materials. The criticality of this technology is related to the use of lead in the photoactive layer. Lead is known to be a heavy metal that can cause various ailments to humans. The biggest problem occurs when cells are disposed of at the end of their life or in case of accidental breakages caused by meteorological or human phenomena. The possible release of lead into the environment, caused by leaching materials, could cause neurotoxicity problems for individuals who come into contact with them. The toxicity of Pb is ranked 2nd in the priority list of toxic substances, respectively (ATSDR, 2015). Lead causes health problems such as insomnia, fatigue, heart problems and weight loss. The International Agency for Research on Cancer classified inorganic lead as probably carcinogenic to humans (Group 2) in 2006 (IARC, 2006) [3] Currently, there is no adequate treatment for photovoltaic devices that contain hazardous metals and their recovery [4] and, the intent of some researchers is to quantify metals of toxicological interest resulting from the leaching of waste materials into environmental matrices. For this purpose, leaching tests can be used to investigate the role of different organic or inorganic molecules used to reduce the release of toxic elements into the environment. Using voltammetric techniques (rapid, cheap and precise) [5] the release of lead from these devices has been studied, therefore the use of a perfluoroalkylated pyrene additive added to the hole transporting material has been evaluated to establish its effect as a screening agent in the release of this metal. The results obtained are promising, the effect that these compounds bring in improving the morphology of these systems has also been evaluated through atomic force microscopy techniques.