Active area cell efficiency (19%) monocrystalline silicon solar cell fabrication using low-cost processing with small footprint laboratory tools
A high efficiency (>\(18\%\)) industrial large area crystalline silicon wafer solar cell fabrication process generally requires industrial equipment with large footprint, high capital and running costs. Stricter processing window, continuous monitoring and automated functioning are the reasons for it. However, for any conventional laboratory (lab) it is always difficult to manage these requirements with limited available lab space or insufficient fund and other related resources. In this work, we report a novel way to fabricate high efficiency full area aluminium back surface field monocrystalline silicon wafer solar cells in our lab using low-cost processing with small-footprint fabrication tools for 6 inch pseudo-square industrial wafers. The novelty of our work includes optimization of every fabrication process step, e.g., texturization, emitter diffusion, emitter passivation and anti-reflection coating deposition, edge-isolation, screen printing and co-firing individually. These modifications include tuning of processing tools and processes, utility changes and inclusion of additional process steps. Beaker-based chemical processes, manual diffusion furnace, introduction of low temperature oxidation, low temperature silicon nitride deposition processes, plasma-edge isolation tool, single manual screen printer, single oven drying of metal pastes and co-firing using rapid thermal processing tools were used at our lab. For our cells, actual and active area efficiencies of 18.5 and 19% (measured under AM1.5G 1 Sun condition), respectively, were achieved.
KeywordsLimited laboratory space small-footprint processing equipment low-cost processing individually optimized processes high-cell efficiency
We would like to acknowledge the efforts of Nimisha S, Aditya D, Divya P and other colleagues at NCPRE for their assistance in characterization and processing. This work was carried out at the National Centre for Photovoltaic Research and Education (funded by the Ministry of New and Renewable Energy, Government of India) under the project no. 16MNRE002 at IIT Bombay.
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