Industrial LCP selective emitter solar cells with plated contacts

Abstract

The investigation of different selective emitter (SE) approaches [1-3] is a current trend in solar cell manufacturing. The incorporation of a local high phosphorous doping underneath the front contact grid allows for the use of high-sheet resistance illuminated emitters that combine low recombination and improved blue response. Further efficiency increase compared to the standard screen-printed solar cell is achieved via plated contacts [4-5] that feature better aspect ratio and optical properties [6], higher line conductivity and smaller width [5] compared to screen-printed contacts. In this paper we present detailed technological requirements for next-generation front side metallization as well as experimental results of the RENA high-efficiency metallization cluster consisting of Laser Chemical Processing (LCP) and Ni-Ag light-induced plating (LIP). It becomes clear that efficiency on cell level is not the only figure of merit for a successful product and that the co mbination of SE with plating has a much higher potential for increasing cell efficiency than the metallization of SE via screen-printing

Evolution of metal plating for silicon solar cell metallisation

“…For dry laser‐doping, the concentration of the phosphorus dopant source and spin‐coating conditions as well as the laser parameters can affect the properties of the laser‐doped regions and consequently also the subsequent LIP . Recent reports have demonstrated that both dry and wet approaches can result in heavily‐doped grooves, which can be metallised using LIP nickel/copper/silver or LIP nickel/silver . Because the patterning process also forms the selective‐emitter, metallisation of laser‐doped front surface grids is a self‐aligning process, thus making the technology attractive for manufacturing.…”

“…For dry laser-doping, the concentration of the phosphorus dopant source and spin-coating Silicon solar cell metallisation A. Lennon, Y. Yao and S. Wenham conditions as well as the laser parameters can affect the properties of the laser-doped regions and consequently also the subsequent LIP [64]. Recent reports have demonstrated that both dry and wet approaches can result in heavilydoped grooves, which can be metallised using LIP nickel/ copper/silver or LIP nickel/silver [27,56,57,59,61,62,65].…”

Crystalline Silicon Solar Cells with Nickel/Copper Contacts

“…Background plating-also known as 'ghost plating' or 'parasitic plating'-is an unwated copper plating that occurs at the passivation layers. Inhomogeneities at the SiN x surface, silicon residuals and cracks are mainly responsible for background plating [99,100]. The phenomenon may affect cell performance by creating undesirable shading and can divest the solar cell aesthetically.…”

Passivation-Induced Cavity Defects in Laser-Doped Selective Emitter Si Solar Cells—Formation Model and Recombination Analysis

“…Due to recrystallization velocities in the order of m/s, proper choice of processing parameters can only minimize the laser-induced crystal damage, but cannot prevent it entirely [1], [4], [5], [8], [9]. Laser processes with long pulses are also suitable for laser-induced selective doping [10]- [12]. Here, dopants from an external source diffuse rapidly within the liquid phase of the molten Si.…”