Oxygen‐alloyed poly‐Si passivating contacts for high‐thermal budget c‐Si heterojunction solar cells

Abstract

Crystalline silicon solar cells with passivating contacts based on doped poly-Si exhibit high optical parasitic losses. Aiming at minimizing these losses, we developed the oxygen-alloyed poly-Si (poly-SiO x ) as suitable material for passivating contacts. From passivation point of view, poly-SiO x layers show excellent passivation quality and carrier selectivity for both n-type (iV OC,flat = 740 mV, contact resistance ρ c = 0.7 mΩ/cm 2 , iV OC,textured = 723 mV) and p-type (iV OC,flat = 709 mV, ρ c = 0.5 mΩ/cm 2 ). Optically, due to the incorporation of oxygen, the absorption coefficient of poly-SiO x becomes much lower than that of doped poly-Si at long wavelength. Both n-type and p-type poly-SiO x layers are concurrently deployed in front/back-contacted (FBC) solar cells with a front indium tin oxide (ITO) layer to

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

“…77 The improved rear-side performance accordingly results in improved overall power generation for TOPCon bifacial for the bifacial cell structure. 9,79 In order to reduce parasitic absorption, adding carbon 80 or oxygen 81 into the poly-Si film is seen as one approach to making poly-Si layers more 'transparent'.…”

“…However, the poly‐Si thin film layers at the rear side of TOPCon cells still have high parasitic absorption, which limits their optical performance, especially for the bifacial cell structure 9,79 . In order to reduce parasitic absorption, adding carbon 80 or oxygen 81 into the poly‐Si film is seen as one approach to making poly‐Si layers more ‘transparent’.…”

Crystalline silicon solar cells with thin poly‐SiOx carrier‐selective passivating contacts for perovskite/c‐Si tandem applications

“…47 The optoelectronic properties of poly-SiO x depend on the oxygen content. 44,48 Poly-SiO x is a novel material that has been successfully employed in c-Si single junction solar cells 44,48,49 and, to the best of our knowledge, its long-wavelength optical potential in tandems has not been explored so far. As these CSPCs are compatible with high temperature production processes, they are appealing to the mainstream c-Si PV industry.…”

“…50 Solar cells fabricated with poly-SiO x CSPCs on an ultra-thin tunnelling SiO x layer grown via NAOS process have exhibited active area efficiency of around 21% in a front/back contacted (FBC) architecture. 49 However, these cells were 2-cm 2 wide and deployed thermally evaporated metal contacts. In this work, next to adopting screen printing for metallization and developing larger area devices (from 2 to 4 cm 2 ), an ultra-thin SiO x layer prepared by thermal oxidation of the c-Si surface is used as tunnelling SiO x .…”

Silicon Nanocrystals Embedded in Nanolayered Silicon Oxide for Crystalline Silicon Solar Cells

“…The conductivity of thick SiO x is beneficial for releasing the solar cells from such a conventional trade-off relationship. Oxygen-alloyed poly-Si passivating contacts have been developed, which achieve good electrical and optical properties. − Although the oxygen-alloyed poly-Si passivating contacts contain silicon nanocrystals (Si NCs) in the SiO x matrix, the size of the Si NCs was almost left to nature. Furthermore, the possibility to add conductivity to thick SiO x has not been explored.…”