Light trapping in pyramidally textured crystalline silicon solar cells using back‐side diffractive gratings

Back‐side diffractive gratings enhance a solar cell's efficiency by trapping light inside the cell and increasing the probability of absorption. We introduce a three‐dimensional, polarization‐sensitive optical model combining ray tracing and rigorous coupled‐wave analysis to investigate silicon solar cells with pyramidal front‐side texturing and back‐side gratings. Parameter optimization is performed to increase the short‐circuit current density for a linear binary grating with grating period p and height h. For the investigated 180‐µm‐thick pyramidally textured silicon solar cells, the simulation yields a maximum enhancement of the short‐circuit current density by ΔJ_SC = 1.79 mA/cm² corresponding to an absolute efficiency increase of Δη = 0.90%. Furthermore, we report on fabrication and reflectance measurements of solar cells with gratings and key challenges in achieving efficiency gains using back‐side diffractive gratings. Copyright © 2012 John Wiley & Sons, Ltd.