Self-aligned Selective Emitter for PERC Based on Inkjetable UV-Polymer

In this study, we investigate and demonstrate the general feasibility of a new approach for a self-aligned selective emitter process technology for passivated emitter and rear cell (PERC) technology based on inkjet printing of an UV-polymer ink in combination with plating for metallization. First, we present the major findings about the single process development of inkjet printing (minimum printed structures of 36 μm), emitter etch-back (from Rsh = 80 Ω/sq to 144 Ω/sq with an etch time of 10 s), low temperature passivation (depositions temperatures of up to 250°C), a lift-off process (at elevated temperatures of 600°C) and demonstrate that the UV-polymer ink shows sufficient chemical and thermal stability to the processes involved. Finally, the successful integration into the PERC process sequence with upscaling to an industrial wafer size M2 and a first working cell device with an efficiency = 19.68% is demonstrated. In comparison, a conventional mask&etch selective emitter approach using inkjet printing of an hotmelt ink in combination with a semi-automated enhanced alignment algorithm between inkjet and screen printing is processed in parallel showing = 21.54% and a gain of = 0.16%abs compared to PERC cell with homogeneous emitter.