Two-level Metallization and Module Integration of Point-contacted Solar Cells

Suppressing recombination on silicon contact interfaces is a topic being addressed for various applications such as photo sensors and solar cells. Although salicidation of the contacts enables low contact resistance, it is usually avoided for these applications as it increases the recombination rate on the contact interfaces. This study explores the use of salicided polysilicon buffer layer in photodiodes' contacts, acting to reduce the recombination rate at the silicide contact. The contact incorporates the advantage of low contact resistance due to silicidation with polysilicon interface that reduces recombination by creating carrier selective junction. The introduction of a polysilicon interlayer was found to increase the short circuit current and the fill factor and to decrease the dark leakage current. The improvement in the light collection parameters was found to be more pronounced under high light intensity (1000 W/m2) than under low light intensity (400 W/m2). The benevolent effect of the polysilicon interlayer is expected to be noticed in devices that are sensitive to contacts' performance. This includes not only image sensors but also high efficiency silicon solar cells.

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Metallization Method for Interdigitated Back-Contact Silicon Solar Cells Employing an Insulating Resin Layer and a Ti/Ag/Cu Metal Stack

Song

Römer

Gentle

et al. 2018

IEEE J. Photovoltaics

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Interdigitated back-contact (IBC) silicon (Si) solar cells are attracting increased attention due to the potential of higher efficiency that comes from eliminating front-surface shading. However, as sources of recombination loss continue to be reduced due to improved processing and use of high-quality n-type wafers, parasitic absorption in the rear metal can limit cell performance. This paper reports experimental and simulation results that identify the optical advantages of an IBC metallization method, which employs a novolac resin layer to enhance the insulation of the cell from a metal electrode comprising a sputtered Ti/Ag metal stack and plated Cu. The polymer layer can electrically decouple the metal geometry from the doping geometry and also helps to reduce the parasitic absorption at the cell rear surface by increasing the distance between the metal and Si absorber. The optical properties of the Ti/Ag stacks formed over the novolac resin were comparable to those with an Ag reflector; however, the Ti/Ag reflector offered the additional benefit of contact resistivity of < 1 mΩ·cm 2 to both the n + and p + Si regions of the diffused IBC cells.

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Two-level Metallization and Module Integration of Point-contacted Solar Cells

Cited by 5 publications

References 9 publications

Decoupling the metal layer of back contact solar cells – optical and electrical benefits

Decoupling the metal layer of back contact solar cells – optical and electrical benefits

Enhancement of carrier collection efficiency in photodiodes by introducing a salicided polysilicon contact

Metallization Method for Interdigitated Back-Contact Silicon Solar Cells Employing an Insulating Resin Layer and a Ti/Ag/Cu Metal Stack

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