Mass production of crystalline silicon solar cells with polysilicon‐based passivating contacts: An industrial perspective

Abstract

Silicon solar cells that employ passivating contacts featuring a heavily doped polysilicon layer on a thin silicon oxide (TOPCon) have been demonstrated to facilitate remarkably high cell efficiencies, amongst the highest achieved to date using a single junction on a silicon substrate. Importantly, it has been shown that the polysiliconbased passivating contacts have a high degree of compatibility with existing mass production processes and toolsets, making them an attractive choice for photovoltaic (PV) cell manufacturers to increase the efficiency of their products. With several large PV manufacturers recently announcing plans to push the TOPCon technology into mass production, we review the significant industrial research and development activities that have been undertaken to push the boundaries of the technology and optimise its integration into the existing mass production pipeline. From an industrial perspective, TOPCon fabrication methodology options as well as necessary technological advances in front-side fabrication, cell metallisation and module integration are discussed. The TOPCon technology development is contextualised in terms of larger trends in PV manufacturing, and we look towards the direction of future industrial development.

Wet chemical poly-Si(n) wrap-around removal for TOPCon solar cells

“…The removal of the poly-Si from the front side and of the edges is thus of utmost importance [1,5]. There are ideas to avoid the wrap-around completely by using physical vapor deposition (PVD) [6] or PECVD masks [7] and this would naturally reduce the required amount of TOPCon process steps [8]. The parasitical poly-Si can successfully be removed by e.g.…”

Poly‐SiOx Passivating Contacts with Plasma‐Assisted N2O Oxidation of Silicon (PANO‐SiOx)

“…[ 5 ] The process of TOPCon technology is highly compatible with existing production lines and thus it is considered to be the next‐generation technology after PERC. [ 6 ] TOPCon solar cells have attracted attention in the PV community and gained a substantial market share after Feldmann et al reported an efficiency of more than 23%. [ 7 ] TOPCon solar cells incorporate at the rear side passivating contacts consisting of n‐type polycrystalline silicon (poly‐Si) and interfacial SiO x layers.…”

“…[25,41] The development of poly-Si or other layers alloyed with oxygen or carbon is crucial in the TOPCon concept to enable carrier selectivity. [6,25,35,38,[42][43][44][45][46] There are multiple techniques that can be used to deposit this layer. PECVD, [23,25,35] low-pressure chemical vapor deposition (LPCVD), [28] as well as sputtering [47] are used to deposit amorphous/polycrystalline silicon thin films.…”