Highly efficient light trapping of clustered silicon nanowires for solar cell applications

Due to their excellent photoelectric performance, nanostructures have attracted considerable attention in research to improve the power conversion efficiency of thin-film solar cells (TFSCs). Furthermore, cylindrical silicon nanowires (Cy-SiNWs) are regarded as promising candidates for a new generation of TFSCs. On this basis, many new nanostructures derived from conventional Cy-SiNWs have been studied extensively, but most of these structures require high manufacturing accuracy because of their complex morphology. In this paper, an ingenious design of clustered silicon nanowires (Cl-SiNWs) is introduced, whose cross section is similar to the flower shape and consists of four arcs with the same radius. Hence, it requires lower manufacturing difficulty compared with nanostructures with curvature variation of the cross-section profile (i.e., elliptic shape, crescent shape, etc.). In this study, the optical and electrical characterizations are numerically investigated using the finite-difference time-domain method. The numerical simulation shows that the optimized Cl-SiNWs achieve an optical ultimate efficiency (η) and circuit current density (J_sc) of 33.66% and 27.54mA/cm², respectively, with an enhancement of 7.3% over conventional Cy-SiNWs. Further, the η and J_sc improve to 42.20% and 34.53mA/cm² by adding the silicon substrate and silver backreflector. More importantly, the η of Cl-SiNWs always obtained a higher value than Cy-SiNWs at a recommended diameter range of 360-560 nm. Therefore, the suggested Cl-SiNWs have exhibited tremendous potential for the future development of low-cost and highly efficient solar cells.