Incident light angle dependence of microwalled silicon solar cell efficiency for fracture transfer printing applications

Herein, we report the results in the search for optimized parameters to fabrication of substrate free microwalled photovoltaic devices for maximum light harvesting. By using the fracture transfer printing method, silicon (Si)-based microwalls (MWs) and micropilars (MPs) with an aspect ratio of 24 were successfully fabricated and transferred into PMMA on secondary substrates. Also, MW solar cell with the filling ratio ∼40% was fabricated by further processing a commercial solar cell with surface texture using deep reactive ion etching (DRIE). The results show that reflection is minimized for light incidence angle greater than 5° with respect to the surface normal to the solar cell plane. The power conversion efficiency (PCE) of the MW PV device starts to increase from 2% as the incident light angle increases from 0° and reaches its maximum at 3.5% for 70°. On the other hand, a textured commercial solar cell, with PCE of 9.5% exhibits decreasing PCE when the incident light angle is varied from orthogonal to parallel orientation with respect to the solar cell plane.