Development of a co-anneal process for double-side TOPCon precursor fabricated by ex-situ POCI3 and APCVD boron diffusion

The aim of this study was to develop a simple and industrially attractive co-anneal process to fabricate a high-quality DS-TOPCon precursor with textured n-TOPCon on front and planar p- TOPCon on rear by ex-situ POCI3 and APCVD boron diffusion. This requires only one high temperature anneal with no additional masking steps. Excellent iVOC of 733mV and iFF of ~86% were achieved after SiNX passivation on both sides, prior to contact firing. Our device modeling projects that this precursor in combination with a manufacturing-friendly poly-Si patterning technique on front can enable> 25% DS-TOPCon cells at low-cost.