Maximizing performance in tunnel oxide passivated contact solar cells: unveiling stability and boosting efficiency through local p+ poly-Si formation

Date

2024-9-06

Author

UYGUN, BERKAY

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Carrier selective passivating contacts are essential for optimizing the efficiency of silicon (Si) solar cells. This thesis explores poly-silicon (poly-Si) grown on SiOx contacts, focusing on their stability during high-temperature processing and efficiency improvements via local poly-Si formation. The research investigates the hydrogenation process and the behavior of phosphorus-doped TOPCon structures under high-temperature fast firing on textured silicon substrates with ALD-AlOx, PECVD-SiNx, and AlOx/SiNx coatings. One of the most critical factors for firing stability is the ultra-thin-tunnel oxide layer, SiOx. By using 1.2 nm SiOx layer, maximum open circuit voltage (iVOC) of 720.6 mV and a saturation current density (J0S) of 3.03 fA/cm² was achieved. Additionally, local boron-doped p+ SiOx/poly-Si structures are developed through wet chemical etching and direct boron-ink application using FlexTrail printing technology. The study also examines the factors influencing etch back selectivity between intrinsic and boron-doped poly-Si. Test structures featuring local TOPCon achieved an iVOC of 720 mV and the lowest J0S for p+ SiOx/poly-Si, ranging from 90 to 120 fA/cm².

Subject Keywords

TOPCon, Stability in TOPCon, Local Poly-Si, Hydrogenation, Fast Fring

URI

https://hdl.handle.net/11511/112267

Collections

Graduate School of Natural and Applied Sciences, Thesis