Chalcogenide on Silicon Tandems (PP3.3)

PP3.3: Chalcogenide on Silicon Tandems

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As an alternative to inorganic III-V materials, chalcogenide semiconductors are another group of promising photovoltaic materials for silicon-based tandems with high efficiency potential, low-cost potential, and demonstrated long term stability.

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This work package will progress the development of metal chalcogenides to target >20% efficiency semitransparent high bandgap chalcogenide cells, and 30% efficiency chalcogenide/silicon tandem cells, using manufacturing sequences compatible with silicon production lines and through the direct growth of top cell and alternative cost-effective tri-chloro-acetic (TCA) bonding technologies.

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PP3.3.1 >20% Efficiency Semitransparent Metal Chalcogenides

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Building on UNSW’s existing world-leading position in metal chalcogenide cell research (pure sulphide chalcopyrite, kesterite, and antimony chalcogenide), the key focuses will be the integration of identified/proven individual key step-change device design technologies to demonstrate the targeted efficiency, and the translation of the sequences to semitransparent architecture.

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To accelerate this progress, comprehensive understanding of the defects and dominating performance loss mechanism will be obtained via combinational density-functional theory calculation, 2D device simulation modelling (under development), and advanced characterisations.

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For the translation to the semitransparent cells, the transparent back electrode architecture will be custom designed to be compatible with chalcogenides' manufacturing processes. Its long-term stability under accelerated stress will be evaluated by collaborating with existing industry partners.

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PP3.3.2  Deposition Processes for High-Mobility Transparent Front Electrode

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Sputtering is generally used for the manufacturing of transparent electrodes for heterojunction solar cells. To reduce the sputtering induced damage, instead of using an intermediate protection layer, alternative soft deposition approaches will be explored. High mobility transparent electrodes by low-temperature soft deposition approaches will minimise the deposition damage and parasitic absorption, realising efficient tandem devices. High-throughput, large area uniformity and long-term stability will be demonstrated in this work package

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PP3.3.3 High-Throughput, Scalable Manufacturing  

Research in this activity will be targeted at:

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1. Demonstration of the direct growth of semitransparent chalcogenide top cells on silicon and glass for one-step and two-step process tandem cells respectively, by using ACAP-funded PVD tandem cluster at the UNSW node.

2. Demonstration of alternative printing manufacturing route built on the new-gen mono-grain membrane approach developed by UNSW researchers, where high quality PV absorber mono-grains are obtained in a stand-alone manufacturing process. This manufacturing approach will allow low temperature printing of top cells and easy control of the transmittance of top cell for current matching.

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PP3.3.4  Low-Cost TCA Interconnected >4” Silicon-Based Tandem Cells

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Low-cost intermediate connection technology is a complementary alternative to the direct growth of top cell on silicon, allowing wide range of top cell options to partner with silicon for 2 terminal/4 terminal (2T/4T) tandem cells.

 

This can be integrated with the semitransparent top cell obtained in PP3.4.3 for two-step tandem cell manufacturing. UNSW researchers’ recent invention of a novel interconnection technology using low-cost TCA bonding layer will be further developed here, which has been proven successful on small-sized silicon-based tandem cells with various semitransparent top cells (e.g., perovskite, III-V, antimony chalcogenide).

 

In this work package, we will adapt this bonding technology for different silicon bottom cells, develop optical design database for various combinations of top cells and silicon bottom cells, and demonstrate large area (>4”) processing capability. Encapsulation and long-term stability test will be co-investigated through the collaboration with industry partners. Life cycle performance, cost and commercialisation pathways will also be evaluated.

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Investigators: Xiaojing Hao, N. Ekins-Daukes, Bram Hoex, Ziv Hameiri, Martin Green (UNSW), Daniel MacDonald (ANU), Jacek Jasieniak (Monash Uni), Anthony S. R. Chesman (CSIRO)