Performance improvement of InP nanowire array solar cells by decorated nanowires and using back reflector

Abstract

Abstract Geometrical design of the vertical arrays of III-V semiconductor nanowires (NWs) is a good candidate for optoelectronic devices due to their ability to excite nanophotonic resonances in the absorption spectrum. Since the appropriate tailoring of radius, length, and pitch is an effective factor in the light absorption of NWs, we first determine the radius and pitch of NWs in which the light absorption of the array is almost the same for different lattices. Then the length at which the best absorption occurs in the NWs is calculated. The plasmonic effect on the performance of the solar cell array is then investigated by calculating the array properties such as adsorption and short-circuit current density using the finite-difference time-domain (FDTD) numerical model. The plasmonic nanostructure is a composite light-trapping structure in which NWs are decorated with gold nanoparticles and an array of gold hemispheres is placed at the rear of the surface as a back reflector. Various geometric shapes such as spheres, cubes, hemispheres, and disks were used to decorate NW with gold nanoparticles, among them spherical gold nanoparticles were more absorbed than other geometric shapes at higher wavelengths, especially at a wavelength close to the bandgap, where most photons are not trapped. It is observed that this light-trapping structure excites plasmonic modes and improves absorption of NWs. Based on FDTD simulation results, the short-circuit current density and maximum photovoltaic efficiency are respectively improved by 8.56% and 13.33% in the proposed structure compared to the bare structure.