Periodic Reporting for period 2 - iSPLASH (Industrial Selective PLAting for Solar Heterojunction)
Berichtszeitraum: 2023-10-01 bis 2025-05-31
Europe aims to lead the clean energy transition, yet most solar cells and panels are still imported and rely on silver, a costly critical raw material with a high environmental footprint. At the same time, European manufacturers face fierce price competition from low cost regions, threatening the resilience of a strategic PV industry.
iSPLASH (“Industrial Selective Plating for Solar Heterojunction”) tackles this challenge by replacing silver with abundant, low cost copper and by delivering a factory ready selective plating tool. The project demonstrates that copper based contacts can match or surpass the efficiency of today’s best heterojunction solar cells, while enabling cleaner and cheaper production in Europe.
Technically, iSPLASH develops an automated machine that gently handles ultra thin wafers, plates copper only where needed and achieves throughputs compatible with gigawatt scale lines. The process operates at low temperature in water based baths and is engineered for robust adhesion, long term reliability and full compliance with EU safety and machinery regulations.
In parallel, social sciences and humanities are integrated through life cycle assessment, techno economic and policy relevant analysis. These studies quantify environmental and cost benefits, assess dependence on critical raw materials and support EU Green Deal and Critical Raw Materials Act objectives, providing evidence for industrial and policy decisions.
The project’s pathway to impact builds on industrial validation with a European gigafactory, preparation for CE marked commercial equipment and active engagement with citizens, policymakers and investors. Beyond photovoltaics, the iSPLASH plating platform opens opportunities in power electronics and advanced semiconductor packaging, reinforcing Europe’s technological sovereignty across several key value chains.
iSPLASH (“Industrial Selective Plating for Solar Heterojunction”) tackles this challenge by replacing silver with abundant, low cost copper and by delivering a factory ready selective plating tool. The project demonstrates that copper based contacts can match or surpass the efficiency of today’s best heterojunction solar cells, while enabling cleaner and cheaper production in Europe.
Technically, iSPLASH develops an automated machine that gently handles ultra thin wafers, plates copper only where needed and achieves throughputs compatible with gigawatt scale lines. The process operates at low temperature in water based baths and is engineered for robust adhesion, long term reliability and full compliance with EU safety and machinery regulations.
In parallel, social sciences and humanities are integrated through life cycle assessment, techno economic and policy relevant analysis. These studies quantify environmental and cost benefits, assess dependence on critical raw materials and support EU Green Deal and Critical Raw Materials Act objectives, providing evidence for industrial and policy decisions.
The project’s pathway to impact builds on industrial validation with a European gigafactory, preparation for CE marked commercial equipment and active engagement with citizens, policymakers and investors. Beyond photovoltaics, the iSPLASH plating platform opens opportunities in power electronics and advanced semiconductor packaging, reinforcing Europe’s technological sovereignty across several key value chains.
The iSPLASH project turned the concept of replacing silver paste with plated copper in heterojunction solar cells into a validated industrial prototype. The team developed water-based copper electrolytes and pulse‑reverse plating tailored to thin wafers, yielding highly conductive copper fingers. An ultrathin nickel buffer between the transparent conductive oxide and copper was introduced to block indium diffusion and ensure adhesion; the Ni/Cu stack was optimized in thickness and thermal budget.
Electrical characterization using four-point probing and simulations showed that the plated copper grid outperforms industrial silver pastes, with very low line resistance. Transfer-length-method patterns and post-anneal studies demonstrated low, uniform contact resistances on both sides of the cell, due to controlled formation of a thin Ni–In alloy at the interface.
Mechanical robustness was verified by peel tests, where adhesion forces exceeded benchmarks and fractures occurred in predefined regions without solar cell damage. In parallel, a compact automated iSPLASH selective plating tool was built, combining tiled plating heads, Bernoulli and vacuum handling, and vision alignment. Hundreds of cells were processed with zero breakage, proving high-throughput, gentle handling.
Statistical process control on copper resistivity, contact resistance, peel strength and cell efficiency enabled tuning of the rear interface, after which all indicators stayed within specifications and the process recipe was frozen. Full cells metallized with iSPLASH reached high efficiencies, matching or slightly exceeding silver-based references through higher fill factor, while life-cycle and cost-of-ownership analyses confirmed lower climate impact, reduced use of critical metals and lower metallization cost.
Electrical characterization using four-point probing and simulations showed that the plated copper grid outperforms industrial silver pastes, with very low line resistance. Transfer-length-method patterns and post-anneal studies demonstrated low, uniform contact resistances on both sides of the cell, due to controlled formation of a thin Ni–In alloy at the interface.
Mechanical robustness was verified by peel tests, where adhesion forces exceeded benchmarks and fractures occurred in predefined regions without solar cell damage. In parallel, a compact automated iSPLASH selective plating tool was built, combining tiled plating heads, Bernoulli and vacuum handling, and vision alignment. Hundreds of cells were processed with zero breakage, proving high-throughput, gentle handling.
Statistical process control on copper resistivity, contact resistance, peel strength and cell efficiency enabled tuning of the rear interface, after which all indicators stayed within specifications and the process recipe was frozen. Full cells metallized with iSPLASH reached high efficiencies, matching or slightly exceeding silver-based references through higher fill factor, while life-cycle and cost-of-ownership analyses confirmed lower climate impact, reduced use of critical metals and lower metallization cost.
The iSPLASH project has advanced copper-based metallisation for heterojunction solar cells beyond the silver-paste state of the art. It delivers a complete, industrial platform – plating chemistry, pulse-reverse process and automated equipment – that forms narrow mask-less, highly conductive copper fingers on thin silicon solar cells with high throughput and low breakage. A ultra-thin nickel buffer layer creates stable, low-resistance contact, giving cell efficiencies at least equal to, and often slightly above, silver references, while maintaining excellent mechanical robustness and adhesion.
Beyond technical performance, iSPLASH quantifies environmental and economic gains. Life-cycle assessment shows major reductions in climate impact and use of scarce metals, and cost-of-ownership analysis confirms significantly lower metallization cost per cell through cheaper materials and removal of high-temperature firing.
The platform is versatile, enabling complex metal stacks and multi-phase solder alloys, opening routes to power electronics and semiconductor packaging in addition to PV. To secure full uptake, key needs remain: large-scale industrial demonstration on thousands of cells to validate performance in real factories; extended reliability testing at module level; and access to investment and markets, including business cases and green finance. A proactive commercialisation and IP strategy, alignment with evolving standards and certification, and international partnerships with global equipment suppliers will support rapid deployment. Overall, iSPLASH moves copper metallisation from promising lab research to a near-industrial reference for clean, resource-efficient solar manufacturing with multi-sector impact potential.
Beyond technical performance, iSPLASH quantifies environmental and economic gains. Life-cycle assessment shows major reductions in climate impact and use of scarce metals, and cost-of-ownership analysis confirms significantly lower metallization cost per cell through cheaper materials and removal of high-temperature firing.
The platform is versatile, enabling complex metal stacks and multi-phase solder alloys, opening routes to power electronics and semiconductor packaging in addition to PV. To secure full uptake, key needs remain: large-scale industrial demonstration on thousands of cells to validate performance in real factories; extended reliability testing at module level; and access to investment and markets, including business cases and green finance. A proactive commercialisation and IP strategy, alignment with evolving standards and certification, and international partnerships with global equipment suppliers will support rapid deployment. Overall, iSPLASH moves copper metallisation from promising lab research to a near-industrial reference for clean, resource-efficient solar manufacturing with multi-sector impact potential.