One of the key challenges of this century is reducing anthropogenic greenhouse gas emissions, a central objective of the European Green Deal and the Horizon Europe Strategic Plan’s goal of achieving net-zero emissions by 2050. This drives research and development in photovoltaic (PV) technology, emphasizing efficiency, stability, cost-effectiveness, scalability, and sustainability. Notably, less than 1% of PV modules are currently manufactured within the European Union. In response, metal-halide perovskite solar cells (PSCs) have emerged as a promising solution due to their low cost, minimal environmental impact, and potential for local production. Supported by the Horizon Europe Framework Programme, the DIAMOND consortium unites academia and industry, bringing together 12 partners from seven European countries to develop and locally manufacture ultra-stable perovskite PV modules. Their aim is to achieve a power conversion efficiency (PCE) above 20 %, using hermetic sealing with innovative glass-frits and a safe-by-design device sealing architecture to prevent leakage. Additionally, the consortium aims to establish designed-for-recycling PV manufacturing approaches. As part of this initiative, DIAMOND Cake is a collaborative effort among PhD students and project researchers focused on developing 6 × 6 cm² and 10 × 10 cm² perovskite PV modules. 

The journey started in Aubonne, Switzerland, at Solaronix (SNX), where the transparent and conductive glass substrates coated with FTO were selectively lasered on 20 samples of each size. The samples were then sent to the University of Porto (UPorto), in Porto, Portugal, where 2 glass frit pastes were screen-printed onto the substrates. These pastes - one Pb-based and the other V₂O₅-based - were later used for laser-assisted glass frit encapsulation to protect the final devices from the external environment. The Ag-based glass frit paste and cover glasses for the encapsulation configuration were also prepared at UPorto. Afterward, the 40 samples returned to Solaronix for the deposition of the electron transport layer of SnO2 via spin coater. At University of Rome Tor Vergata (UTV), in Rome, Italy, the perovskite layer was deposited by blade coating. Afterward, the substrates were sent to Freiburg, Germany, where the team at Fraunhofer ISE deposited CEAI (cyclohexylethylammonium iodide) and Spiro-OMeTAD as the perovskite passivation layer and hole transport layer, respectively. This step was followed by carbon lamination to form the back electrodes. The modules went once again to UPorto to be laser-sealed at a process temperature of 55 ºC and later characterized. Finally, part of the modules was aged at University of Marburg (UM), Marburg, Germany, and another part at CEA, in France, to assess the stability of the devices in different tests, namely, thermal cycling, ageing at MPPT under elevated temperatures, continuous illumination and outdoor monitoring. This project brought together PhD students and researchers from various institutions, each contributing with their expertise to ensure the final devices were high-performing and durable-all while enjoying the experience of working together on a collaborative module.