Optical light management by self-arrangement of inverted tetragonal pyramids on the silicon surface through copper-assisted etching technique in a single step

Abstract

Developing efficient light trapping techniques plays a crucial role in improving silicon (Si) solar cell parameters by decreasing optical losses. Herein, four various surface morphologies by copper-assisted chemical etching (Cu-ACE) technique under various process conditions were developed. The etching solution is composed of copper nitrate trihydrate (Cu[NO3]2), hydrofluoric acid, and hydrogen peroxide in deionized water. The systematic correlation study on the molarity of the chemical ingredients reveals that the final surface morphology is strongly dependent on the molarity of Cu(NO3)2, resulting either in porous-like or micro elliptical shaped or inverted pyramid (IP) structures on the surface of p-type Si. The novel surface morphology, tetragonal-star-shaped IPs, is accomplished by gradually increasing process temperature from 50°C to 55°C in 15 min, resulting in an extremely low weighted reflectance value of 2.65% on a p-type Si wafer. Furthermore, aluminum back surface field Si solar cells were fabricated using the standard upright and novel tetragonal-star-shaped inverted pyramidal structures. The short-circuit current density and conversion efficiency values of the fabricated solar cells are significantly improved by the implementation of the tetragonal-star-shaped IPs, where short-circuit current density values are enhanced by 3% compared to the case where texturing with upright pyramids was applied. © 2022 John Wiley & Sons Ltd.