Currently the efficiency-to-cost ratio among the diverse photovoltaic techniques remains too low to compete with fossil energy. To boost this ratio, it is critical to enhance the conversion efficiency (CE) or to lower the cost of solar cells (SCs). Therefore, in this study we employ a series of wet and room-temperature electrochemical processes to fabricate low-cost Si nanohole-based solar cells (SiNH-based SCs). The SiNH-based SCs demonstrate excellent antireflective properties, resulting in a leading CE of 10.03% with a low cost in the field of Si-nanostructured SCs. In addition, these SiNH-based SCs possess additional advantages of robust structures and greater fill factor, and can be readily employed for practical photovoltaic applications.Pursuing an alternative energy source is an important global endeavor because of the shortcomings of fossil energy and growing environmental concerns. Among the various renewable energy sources, solar energy captured with photovoltaic (PV) cells is promising because of its permanence and cleanness. Of the various types of solar cells (SCs), Si-based SCs currently dominate the PV market, with a share greater than 90%, 1 because they have two quintessential advantages over other types of SCs. First, Si is the second most abundant element on the earth; second, the fabrication process is compatible with the mature integrated-circuit industry. Nevertheless, currently, Si-based SCs still cannot compete with fossil energy, mainly because of their relatively poor efficiency-to-cost ratios. 2 Thus, it is an important challenge to reduce this ratio by lowering the cost of solar cells (SCs) or by improving the performance. One way to enhance the efficiency-to-cost ratio is to introduce an innovative architecture, such as the radial p-n junction SC. This special architecture decouples the routes of light absorption and the diffusion paths of minor carriers to two orthogonal directions, 3 significantly improving the conversion efficiency (CE) of the cell with a shallow active layer; the high-aspect-ratio Si nanostructures are the best candidates from this point of view. 4-6 Another way to increase the efficiency-to-cost ratio is to employ a good antireflection (AR) layer. Typically, however, the fabrication of the AR layer requires a series of tedious and expensive procedures, so the cost of SCs is still not competitive with that of fossil energy.Recently, it has been reported that Si nanowires (SiNWs) 7-10 and Si nanoholes (NHs) 11 with high aspect ratios possess significant light-trapping capabilities and could serve as an AR layer for SCs. Several methods have been used to fabricate SiNWs, including vapor-liquid-solid growth, 5, 12-14 deep reactive-ion etching, 8,15 solution-grown processing 16 and oxide-assisted growth, 17, 18 but they are unfeasible for practical applications because of the following drawbacks: high process temperatures, 5, 12-14, 16-18 random growth orientations, 5, 12-14, 16-18 saturated impurities of the catalysts 5, 12-14, 16 and expensive fabrication costs. 5,...
