Optical and electrical characteristics of dome tapered silicon nanowires for efficient photovoltaic solar energy conversion

The optical and electrical characteristics of novel dome-shaped nanowires (NWs) are reported for energy harvesting applications. In order to show the superiority of the suggested design, a comparison is made with cylindrical and other tapered nanowires such as conical and horn-shaped NWs. A tapering parameter is introduced to control the NW geometry and its optical and electrical efficiency. Further, the different geometrical parameters are investigated using finite difference time domain to minimize the light reflection and maximize the absorption through the suggested designs. It is evident that the tapering parameter effectively can control the NW-tip geometry to achieve optimum light coupling. The dome-shaped NW design has a good light confinement with better absorption compared to the horn and conical NW structures. This is due to the supported MIE-based mode resonances over a broad wavelength range. Further, the top diameter of the dome-shaped NWs supports more guided modes with high intensity and better light coupling. Besides, the light reflections between the tapered NWs improve the light coupling with the NWs where the optical path length of low frequencies is increased with improved light absorption. Therefore, the reported design with tapering factor of 2.2 achieves an average absorption of 81% with an improvement of 9.5% over the absorption of the conical NWs SC. Further, photo-generated current density and optical efficiency of 37 mA/cm² and 41% are obtained by the reprted design with an enhancement of 22% and 8.8% compared to conventional cylindrical and conical NWs, respectively. Further, the electrical efficiency is simulated using the finite element method considering the recombination effects. The power conversion efficiency of the dome-shaped array is equal to 15.96%, with an enhancement of 32% and 17.5% relative to cylindrical and conical NWs, respectively. The fine-tapered NW with a dome-shaped design is a crucial step toward realizing highly efficient NWs–SC with cost-effective material savings.