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Published September 29, 2021 | Supplemental Material
Journal Article Open

Silicon Heterojunction Microcells


We report the design, fabrication, and characterization of silicon heterojunction microcells, a new type of photovoltaic cell that leverages high-efficiency bulk wafers in a microscale form factor, while also addressing the challenge of passivating microcell sidewalls to mitigate carrier recombination. We present synthesis methods exploiting either dry etching or laser cutting to realize microcells with native oxide-based edge passivation. Measured microcell performance for both fabrication processes is compared to that in simulations. We characterize the dependence of microcell open-circuit voltage (V_(oc)) on the cell area–perimeter ratio and examine synthesis processes that affect edge passivation quality, such as sidewall damage removal, the passivation material, and the deposition technique. We report the highest Si microcell V_(oc) to date (588 mV, for a 400 μm × 400 μm × 80 μm device), demonstrate V_(oc) improvements with deposited edge passivation of up to 55 mV, and outline a pathway to achieve microcell efficiencies surpassing 15% for such device sizes.

Additional Information

© 2021 American Chemical Society. Received: July 20, 2021; Published: September 14, 2021. This work (design and fabrication of microcell materials, microcell modeling, and microcell characterization) has been primarily supported by the Photonics at Thermodynamic Limits Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under award number DE-SC0019140. A.A. acknowledges support from NSF and the Department of Energy (DOE) under NSF CA no. EEC-1041895 and DE-EE0008975. We acknowledge the Kavli Nanoscience Institute at Caltech for providing the infrastructure for part of this EFRC-funded work and helpful conversations with staff members Bert Mendoza, Nathan Lee, and Alex Wertheim. We would also like to thank the PPG-MRL Graduate Research Assistantship Award for supporting this project. Author Contributions: M.M.P. and M.E.P. contributed equally to the work. Conceptualization: M.M.P., M.E.P., H.A.A., and R.G.N. Methodology: M.M.P. and M.E.P. Investigation: M.M.P., M.E.P., R.D.G., P.B., and H.C.B. Resources: P.B. and A.A. Writing: M.M.P. and M.E.P. Review and editing: P.B., P.J., H.C.B., R.D.G., C.M.W., M.J.E., D.R.N., A.A., R.G.N., and H.A.A. Supervision: R.G.N. and H.A.A. Funding acquisition: R.G.N., H.A.A., and A.A. The authors declare no competing financial interest.

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August 22, 2023
October 23, 2023