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This paper reports broadband anti-reflection in black silicon (b-Si) fabricated by two-step metal-assisted chemical etching (MACE) for potential photovoltaic (PV) applications. The method involves deposition of silver nanoparticles (Ag NPs) in aqueous solution of HF:AgNO3, followed by etching in HF:H2O2:DI H2O solution for different duration (10-25 s). Effects of etching time towards surface morphological and optical properties of b-Si nanowires are investigated. Surface morphological characterization confirms presence of b-Si nanowires with heights of 350-570 nm and diameter of 150-300 nm. The b-Si nanowires exhibit outstanding broadband anti-reflection due to refractive index grading effect. This is represented as weighted average reflection (WAR) in the 300-1100 nm wavelength region. After 20 s of etching, b-Si nanowires with height of 570 nm and width of about 200 nm are produced. The nanowires demonstrate WAR of 5.5%, which represents the lowest WAR in this investigation. This results in absorption of 95.6% at wavelength of 600 nm. The enhanced broadband light absorption yields maximum potential short-circuit current density (Jsc(max)) of up to 39.7 mA/cm2, or 51% enhancement compared to c-Si reference. This facile b-Si fabrication method for broadband enhanced anti-reflection could be a promising technique to produce potential PV devices with high photocurrent.

Thinning of crystalline silicon (c-Si) wafer is a promising approach to reduce the technology cost of passivated emitter rear cell (PERC) solar cell. However, reducing the wafer thickness compromises light absorption, hence short-circuit current density (Jsc) in the solar cell. This necessitates effective light trapping in the device. In this work, upright cone textures are incorporated on the surface of 50 μm PERC monocrystalline silicon solar cell. SunSolve ray tracer is used to simulate the optical and electrical properties of the solar cell within 300-1200 nm wavelength region. Besides, the solar cell is also simulated with a front silicon nitride (SiNx) anti-reflective coating (ARC) on the cone textures. From the results, the thin PERC solar cell with cone textures and SiNx ARC demonstrates Jsc of up to 38.8 mA/cm2 and conversion efficiency of 20.4%. This is a significant performance improvement when compared to the planar cell, with Jsc of 25.1 mA/cm2 and efficiency of 13.1%. The improvement is attributed to the enhanced broadband light absorption and increased external quantum efficiency in the device.