Optoelectronic performance of radial-junction Si nanopillar and nanohole solar cells

Two typical radial-junction structures, Si nanopillars (SiNP) and nanoholes, were modeled and compared for solar cell applications. From the physical model using the transport equations, the output performances, e.g., short-circuit current density, open-circuit voltage, energy conversion efficiency, fill factor, etc., were simulated. A maximum efficiency of 21.0% was predicted for Si nanoholes, demonstrating a superior performance of the radial-junction structure compared to SiNPs (14.6%). Also, the dependence of the conversion efficiency on various structural parameters, e.g., substrate thickness, height, feature radius, junction depth, emitter doping concentration, as well as front and back surface recombination velocities, etc., was investigated, providing a design principle for high-efficiency radial-junction solar cells.