Numerical analysis and device optimization of radial p-n junction GaAs/AlxGa1−xAs core-shell nanowire solar cells

Based on the transfer-matrix method and the complex wave impedance approach, this unified electrical and optical numerical simulation thoroughly analyzes the impacts of the design parameters on the transport mechanisms and device characteristics of radial p-n junction GaAs/Al_xGa_1-xAs core-shell nanowire solar cells. By optimizing the doping density of the core and shell, core radius, shell thickness, nanowire length as well as the Al mole fraction of the n-type Al_xGa_1-xAs shell, the optimized device exhibits an open-circuit voltage of ~0.94V, a short-circuit current of ~55.5 pA (effective short-circuit current density is ~40.9 mA/cm²), and a fill-factor of ~0.76. Hence, this clearly shows that radial p-n junction GaAs/Al_xGa_1-xAs core-shell nanowire solar cell on Si substrate is capable of achieving an unprecedented solar cell efficiency of ~30% for single-junction GaAs solar cells in a cost-effective way.