Novel Schemes of p+ poly-Si Hydrogenation Implemented in Industrial 6'' Bifacial Front-and-Rear Passivating Contacts Solar Cells

Abstract

In this paper we present our latest developments in bifacial 6” cells featuring polysilicon carrier-selective passivating contacts which can be seen as an upgrade to bifacial cell architectures such as PERC+ and PERT. In this study we present improvements of p+ polySi passivation on industrially relevant textured surfaces by means of advanced hydrogenation schemes, involving novel dielectric stacked layers, and modification of the B-profile leading to a record passivation level of ~8 fA/cm2 and 724 mV before firing and ~9 fA/cm2 and 722 mV after firing. The results promote industrial implementation of p+ polySi on 6” bifacial cells with excellent passivation properties and compatibility with screen-printed and fire-through metallization, especially as our latest results show Jo,contact being reduced down to 200 fA/cm2. Bifacial solar cells have been manufactured with industry compatible processing with front-and-rear passivating contacts with efficiencies above 20% in the first attempt and this development shows a potential of 23% with a bifaciality factor of 90%.