A novel recycling method for encapsulated perovskite mesoscopic photovoltaic devices with minimal performance loss

The rapid development of photovoltaic (PV) industry in the last decades enabled devices with high power output, stability and low cost, currently available on the PV market. However, PV must also provide low environmental burden. In the context of sustainability, unique features of perovskite PV, such as liquid processing, defect tolerance and high absorption coefficient become particularly appealing, since they allow rapid fabrication of such devices without energy- and material-intensive manufacturing steps. These advantages can potentially reduce the negative environmental impact of PV modules. For example, green-house gas emissions originating from global PV manufacturing are expected to exceed the emissions of some European countries within the next decades, if the PV learning rate will not be able to keep up with the pace of increase in global energy consumption. Moreover, problems of waste flow associated with PV industry as well as depletion of ore and materials needed for conventional silicon (Si) PV modules become key challenges the PV sector are currently facing. Among different types of perovskite PV devices, the ones with carbon-based electrodes are currently capable of fulfilling most of the conditions for commercializing an emerging PV technology: (1) high efficiency, (2) high stability and (3) low cost. In order to test whether such devices can also meet the last requirement: (4) sustainability, we conducted a life-cycle assessment (LCA) on perovskite PV modules with carbon electrodes, encapsulated with thermoplastic polyolefin (TPO) and polyisobutylene (PIB) edge-seal. Such encapsulation method provides sufficient protection against device degradation, as evident from our results of continuous maximum power point-tracking of encapsulated modules placed outdoors for 2,000 hours. The results from LCA highlight that the global warming potential (GWP) of such modules is only 247.2 kg CO2-eq./kWp, which is more than twice lower than that of conventional Si-PV modules. Based on the presented LCA, we identify the module components with the highest environmental burden, which should be recycled (or re-used), in order to reduce the GWP further. Finally, we demonstrate a novel method to recycle such encapsulated devices using a simple temperature-assisted mechanochemical approach with performance loss of <10%rel. after the recycling loop is complete. We estimate that this recycling method is able to reduce their CO2-footprint by up to 1/3, underlining that perovskite PV devices with carbon-based electrodes provide strong potential to reduce environmental impact of next-generation PV modules.