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The rear side metallization of Si solar cells comes with a number of inherent losses and trade-offs: a larger metallized area fraction improves fill factor at the expense of open-circuit voltage, depositing directly on textured Si leads to low contact resistivity at the expense of short-circuit current, and some metallization processes create defects in Si. To mitigate many of these losses we have developed a novel approach for rear side metallization of Si solar cells, utilizing a transparent conducting adhesive (TCA) to metallize Si without exposing the wafer to the metal deposition process. The TCA consists of an insulating adhesive loaded with conductive microspheres. This approach leads to virtually no loss in implied open-circuit voltage upon metallization. Electrical measurements showed that contact resistivities of 3-9 Ωcm2 were achieved, and an analysis of the transit resistance per microsphere showed that

Methods of making silicon based tandem cells include wafer bonding, depositing absorber layers on the surface, and mechanical stacking. Of these, mechanically stacking after growth retains the individual cell quality during production, but typically requires a four-terminal device. We present a transparent conductive adhesive (TCA) interlayer, designed for transparency in wavelengths that Si absorbs, conductivity for out-of-plane conductivity between cells, and adhesive strength, enabling two-terminal stacked tandems. The developed TCA material is a polymer-particle blend of common transparent adhesives and metal-coated flexible microspheres, capable of bridging micro-scale gaps between uneven/textured surfaces. At 10% microsphere coverage, experimental and theoretical series resistance is compatible with high-efficiency tandem cells on silicon.