  In this paper, we have designed and investigated the performance of radial
GaAs/AlGaAs pin junction nanocone array solar cells by performing coupled
optoelectronic simulations to obtain the most optimal design configuration
based on its photovoltaic properties. Each model has been compared with its
GaAs shell counterparts for different levels of surface passivations. It has
been observed that the nanocones with the AlGaAs shell has a much better
performance compared to those having GaAs shell. AlGaAs shell acts as a strong
barrier restricting most of the photogeneration to the inner GaAs regions and
it also acts as a strong passivation layer, reducing the recombination losses
due to surface effects. Further, it is observed that the nanocones achieve
their highest photoconversion efficiency when they are sparsely packed, with a
constant i-shell thickness of 7-9 nm and have an angle of tilt of 5 degrees.
This enhanced performance is attributed to a more effective and extended
photogeneration throughout the nanowire length, a strong overlapping built-in
electric field, and lower recombination losses.
