Numerical analysis of InP based high efficiency radial junction nanowire solar cell

Abstract

III-V nanowire (NW) solar cells (SCs) promise a comparable efficiency to that of their planar counterparts with additional advantage of reduced material consumption to cut the manufacturing cost. However, the disadvantage of low minority carrier lifetime due to the large surface-to-volume ratio of NWs degrades its photovoltaic performance to some extent. To overcome this issue, the structure of radial junction instead of axial junction for NWSCs has been used, but in experimental realization, defect density increases in the radial junction structure at the interface of core/shell, resulting in low performance. In this paper, we propose a high performance radial junction NWSC, consisting of p-InP NW coated by Ta 2 O 5 and ITO, and simulate it using Lumerical software. The results show that the use of ITO/Ta 2 O 5 shell over the InP NW as an electron selective contact enhances the absorption of incident photons, which in turn increases efficiency, also providing the condition that the InP required for core can be reduced without sacrificing the ideal current density, leading to a decrease in the fabrication cost. Besides, we investigate and compare the photovoltaic parameters of the structures of ITO/Ta 2 O 5 /p-InP NWSCs with circular and rectangular cross-section in terms of minority carrier life time, doping, and surface recombination velocity (SRV). It is found that circular and rectangular NWSCs with the same filling ratio possess almost the same optimized ideal photo-current such that for the carrier life time of 400 ps and the SRV of less than or equal to 10 4 cm/s at the interface of Ta 2 O 5 /InP, an efficiency as high as ~24.5% and ~25.6% can be achieved for circular and rectangular NWSCs, respectively. • Performance of cylindrical and rectangular InP NW studied using FDTD method. • Optimization of nanostructures is performed in terms of optical Jsc. • Oxide shell ITO/Ta 2 O 5 is used to enhance the absorption and J sc . • Influence of carrier lifetime, doping, and SRV on photovoltaic performance is investigated. • PCE of ~24.5% and ~25.6% is achieved with cylindrical and rectangular NW respectively.