INSPIRE-PV · INterface engineering of carrier-Selective, Passivating and Interconnecting REcombination junctions for Tandem PhotoVoltaics

The world is currently facing the perils of climate change, which manifest in the form of severe weather events across the globe, resulting not only in substantial economic losses but also endangering human life. A long-term solution is to transition to renewables, and solar photovoltaics stand out for its potential to significantly displace conventional fossil fuels. For enabling this transition, the solar cells should deliver higher efficiency in an economically feasible and commercially scalable manner. The current market-dominant silicon solar cells have reached efficiency close to their upper limit of ~27%. A promising route to improve this further is tandem solar cells (TSCs), which integrate two solar cells - a perovskite top cell and a silicon bottom cell, already demonstrating ~34% record efficiency. However, the widespread adoption of TSCs is hindered by the limitations of the interconnecting recombination junction (RJ). This critical layer must exhibit high optical transparency to minimize photon losses, exceptional passivation to suppress carrier recombination, and compatibility with scalable manufacturing processes. The present layers consist of Indium-based transparent conductive oxides (TCOs), which suffer from high material cost and resource scarcity, along with amorphous silicon (a-Si) that has parasitic absorption losses. Project INSPIRE-PV aims to engineer a next-generation RJ offering three key advantages: (1) replacement of indium-based TCOs with cost-effective, scalable alternatives; (2) enhanced transparency through wide-bandgap materials; and (3) superior interface passivation enabled by hydrogen plasma treatment. This novel material stack addresses a critical bottleneck in tandem cell design, unlocking pathways toward economically viable, high-efficiency TSCs. This interdisciplinary effort seeks to establish a new benchmark in TSC architecture, facilitating mass deployment and contributing meaningfully to global decarbonization goals.