This final report summaries the development of ANU’s world-leading monolithic Si/perovskite tandem solar cells architecture, project outcomes and lessons learnt.
Tandem solar cell has emerged as one of the most promising approaches to further reducing the cost of solar cells by enhancing their efficiency. Among the contenders, the perovskite solar cell stands out as the most promising top cell to partner with silicon (Si) cells in tandem architecture, thanks to its superior optoelectronic properties, impressive efficiency, and the potential for low-cost production. However, the complexities and inclusion of expensive materials and fabrication processes in Si/perovskite tandem architectures, coupled with low material usage during deposition, leads to a substantial increase in manufacturing costs. The pioneering work on the interconnect-free Si/perovskite tandem solar cells led by the ANU team presents an important and promising solution to this challenge.
The objective of this project is to advance Si/perovskite tandem technology towards commercial viability by making significant strides in three key domains: cost, efficiency, and lifetime, building on the simplified tandem cell architecture pioneered by the ANU team. Innovative efforts have been made on both the Si and perovskite subcells, as well as their interfaces. In terms of Si subcells, the
project has pioneered a low-cost, double-sided poly-Si/SiO2 passivating contact cell using industrially relevant processes, as well as developed and introduced cutting-edge dopant-free Si cell technology for tandem application. For the perovskite subcells, comprehensive material innovations and device optimisation having been demonstrated to produce high-quality perovskites and their functional layers, leading to the achievement of high-performance and durable perovskite cells apt for tandem applications at low cost simultaneously. Moreover, meticulous material and interface engineering have been conducted and played a crucial role in simplifying the tandem architecture and realising the efficient interconnect-free tandem design on various Si technologies. Integrating the subcells with the simplified, interconnect-free tandem architecture leads to state-of-the-art tandem performances of over 29%, the highest for the same type.
To enhance the stability of the Si/perovskite tandem solar cells, both intrinsic strategies—aimed at improving material stability—and extrinsic strategies focusing on robust encapsulation to minimise efficiency loss and prevent moisture and oxygen infiltration have been developed. The encapsulated state-of-the-art tandem cells have met some rigorous industrial benchmarks set for commercial Si
solar cell technology. Technoeconomic evaluations have been conducted throughout the project, which not only guides the project’s progression but also furnish invaluable insights to the wider community. These achievements significantly elevate the technology readiness level of the Si/perovskite tandem solar cells, setting the stage for commercial readiness and an economically sustainable renewable energy future.