Our research is focused on developing high efficiency and low cost silicon solar cells by using nanostructured “black silicon” (b-Si) antireflection (AR) layer. B-Si can be manufactured simply by adding a dense network of nanoscale needles on top of a standard silicon wafer. Modifying the material in this way makes it a lot less reflective, allowing solar cells that use it to trap light even when it's coming from very low angles. This could be a good way to increase the yield of solar cells throughout the day, particularly in countries at higher latitudes. To deeply study the influence of the 3D texturization of b-Si on the reflectivity, simulations based on the Finite-Difference Time-Domain method have been performed. We have simulated the textured structures consisting of cones of nanometres dimensions with different heights and diameters for the optical wavelength. We observed that a b-Si structure with the sharpest and high density cones is expected to obtain the lowest reflectivity. Besides, the influence of the direction of the incident field on the reflection of b-Si cannot be neglected.   Based on the favourable simulation results, b-Si layers in surface of silicon wafers was fabricated by Inductively Coupled Plasma Reactive Ion Etching in a gas mixture of SF6 and O2 at noncryogenic temperatures. The structure evolution and the dependency of final structure geometry on the main processing parameters (gas composition and working pressure) are investigated and explained comprehensively. The optical properties of the produced b-Si layers, a distinct AR and light trapping effect, are resolved by optical spectroscopy and conclusively illustrated by optical simulations of accurate models of the real nanostructures. By analysis of a multitude of b-Si layers fabricated under different conditions, approximate limits for the range of feasible nanostructure geometries are derived. It was shown that there is a significant reduction of reflection index for b-Si with long densely packed needles at height of 650 nm.   A production process sequence for solar cells with b-Si AR layer was substantiated, developed and tested according to which, the b-Si with preferable height of needles is formed after the main chemical and thermal treatment of the technological process.   We have manufactured a b-Si as the AR layer on common (industrial) silicon solar cells These solar cells present excellent antireflective behavior with a reflectance below R=2% in the spectral range of 580-1050 nm. This reflectance level is the best published in the literature to our knowledge, for b-Si AR layer obtained by plasma etched method.   The efficiency of solar cell samples with b-Si AR layer have been significantly improved (8%), while the efficiency of light detection is almost unchanged for the light flux with the angle of incidence up to 50° This could be a good way to increase the yield of solar cells throughout the day.   The commercial viability of the b-Si technology is quite feasible, since the technology is scalable and inexpensive. This technology is also compatible with current industrial fabrication of Si solar cells.