This paper presents the fabrication and optical properties of hydrogenated amorphous silicon (a-Si:H) nanowire (NW) and nanocone (NC) arrays. The authors demonstrate a scalable and IC-compatible process for creating these nanostructures using a wafer-scale Langmuir-Blodgett assembly and etching technique. The nanostructures exhibit enhanced optical absorption due to suppressed reflection. The NC arrays, in particular, provide nearly perfect impedance matching between a-Si:H and air through a gradual reduction of the effective refractive index. This results in significantly higher absorption compared to NW arrays and thin films. At angles of incidence up to 60°, over 90% of light is absorbed by NC arrays, which is much higher than NW arrays (70%) and thin films (45%). The absorption of NC arrays is also higher at the band gap edge of a-Si:H (88%) compared to NW arrays (70%) and thin films (53%). The experimental data agree well with simulations. The a-Si:H NC arrays function as both absorbers and antireflection layers, offering a promising approach to enhance the solar cell energy conversion efficiency. The study highlights the potential of a-Si:H NC arrays for low-cost, large-area solar cell devices and other applications benefiting from antireflective coatings.This paper presents the fabrication and optical properties of hydrogenated amorphous silicon (a-Si:H) nanowire (NW) and nanocone (NC) arrays. The authors demonstrate a scalable and IC-compatible process for creating these nanostructures using a wafer-scale Langmuir-Blodgett assembly and etching technique. The nanostructures exhibit enhanced optical absorption due to suppressed reflection. The NC arrays, in particular, provide nearly perfect impedance matching between a-Si:H and air through a gradual reduction of the effective refractive index. This results in significantly higher absorption compared to NW arrays and thin films. At angles of incidence up to 60°, over 90% of light is absorbed by NC arrays, which is much higher than NW arrays (70%) and thin films (45%). The absorption of NC arrays is also higher at the band gap edge of a-Si:H (88%) compared to NW arrays (70%) and thin films (53%). The experimental data agree well with simulations. The a-Si:H NC arrays function as both absorbers and antireflection layers, offering a promising approach to enhance the solar cell energy conversion efficiency. The study highlights the potential of a-Si:H NC arrays for low-cost, large-area solar cell devices and other applications benefiting from antireflective coatings.