Constraints and Opportunities for Co2-Neutral Photovoltaics: In-Situ Perovskite Solar Cell Manufacturing Enables Reaching the Ultimate Carbon Footprint Limit of the Glass Substrate

Photovoltaics (PV) is on the way to become a global key energy technology. As PV is replacing fossil fuel based technology, it contributes to reduce the global CO2-emissions. However, it should be kept in mind that the fabrication of PV modules is connected with CO2 emission. To fulfil the Paris climate goals, the global PV industry needs to grow in such a way that it will have a significant share in global carbon emissions. Research-driven approaches to reduce the carbon footprint of PV have strong impact on this development. We identify the glass substrate and encapsulation as the ultimate lower boundary for carbon footprint for long-term stable grid connected PV technologies. By the in-situ concept for perovskite solar cells we introduce a holistic design approach guided by this lower limit for photovoltaic modules with a low carbon footprint of only 5% of current silicon PV. The feasibility of this idea is demonstrated by the fabrication of an efficient pre-encapsulated perovskite in-situ cell. The device shows record efficiencies of certified, stabilized 9.3 %. This is the highest reported efficiency of such solar cells with lowest carbon footprint.