23. record efficiency of graphene/silicon solar cell with passivated back contact

Department: Mechanical & Aerospace Engineering
Research Institute Affiliation: Agile - CaliBaja Center for Resilient Materials & Systems
Faculty Advisor(s): Prabhakar R. Bandaru

Primary Student
Name: Serdar Yavuz
Email: seyavuz@ucsd.edu
Phone: 858-534-2437
Grad Year: 2018

Using graphene as a transparent conductive electrode for solar cell has attracted enormous attention due to the cost effective device fabrication. Recently, power conversion efficiency (PCE) of 15.6% has been obtained by placing graphene on n-silicon (Gr/Si) combined with doping of graphene and anti-reflection coating. However, many of Gr/Si solar cells reported so far have suffered from the low open circuit potential (Voc) and fill factor (FF) which limits the PCE of Gr/Si solar cell compared to the p-n junction counterparts. In this work, we applied a passivation layer at the rear contact of Gr/Si solar cell to reduce the recombination which, accordingly, leads to higher Voc and FF. We systematically showed that passivation layer improves the lifetime of carriers by reducing the surface recombination velocity and obtained a FF of 0.77 which is the highest FF reported for Gr/Si solar cell so far. Furthermore, to mitigate the current loses due to the high sheet resistance of graphene, we optimized the active area of solar cell and obtained a bare cell efficiency of 11%. By applying a chemical doping and employing an anti-reflection coating, a new record efficiency of 16.7% has been achieved which is high enough to compare with p-n junction counterparts. Our approach shows that over 18% efficiency combined with a front surface passivation layer is possible for Gr/Si solar cell.

Industry Application Area(s)
Energy/Clean technology | Materials | Semiconductor

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