Establishment of a novel functional group passivation system for the surface engineering of c-Si solar cells.

Abstract Surface engineering of crystalline silicon (c-Si) is the core of Si-based semiconductor devices. The current commercially available c-Si solar cells achieve this by making use of a conventional thin dielectric film passivation system (TDFPS), including SiO 2 , Al 2 O 3 , SiN x :H and hydrogenated amorphous silicon (a-Si:H) in industry. However, the TDFPS requires high-vacuum and/or high-temperature conditions, which hinders efforts to further reduce the costs of device fabrication. A revolutionized approach to circumvent these issues involves the replacement of TDFPS with new material system which can also achieve high-quality passivation on c-Si surface. Here, we successfully establish and implement a functional group passivation system (FGPS) using a series of functional materials with a sulfonic functional group -SO 3 H, such as 'poly(2-acrylamido-2-methylpropanesulfonic acid)' (PAMPS) and 'polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene, sulfonated, cross-linkable' (PS-b-PERB), which can achieve a highly effective passivation on Si surface, resulting in power conversion efficiencies up to 20% when they are applied in the front surface engineering of interdigitated back contact (IBC) solar cells. Furthermore, the FGPS materials inherently allow passivation layer fabrication in low-temperature and high-vacuum-free conditions. This work provides novel low-cost material strategies without compromise of performance for c-Si surface engineering in the future Si-based photovoltaics. Graphical abstract Image 1 Highlights • It is found that the sulfonic acid group, –SO3H, in a material is responsible for the high-quality passivation effects of this type of material, leading to the discovery of a series of passivation schemes. • A new materials system, i.e., functional group passivation system, is established to engineer Si surface for the suppression of surface/interface recombination. • A multi-functional anti-reflection/surface passivation material, PS-b-PERB film, is developed and applied in the front surface engineering of IBC solar cells, with high power conversion efficiency of 20%. [ABSTRACT FROM AUTHOR]