We first fabricated a p-type single-crystalline SiNW array as the core by statistic electroless metal deposition (SEMD) method. This structure exhibits per excellent absorption efficiency without increasing the diffusion path, indicating 1.75 times greater performance than Si-based planar solar cells under the same condition. Next, we employed a method of spin-on dopant (SOD) to fabricate an n-type layer as an external thin shell, which benefits to decouple the absorption of light from charge transport by allowing lateral diffusion of minority carriers to the p-n junction rather than many microns away as in Si bulk solar cells, and is suitable for our SiNW array with a hydrophilic surface. Finally, our SiNW-based solar cell possesses strong broadband absorption and low reflection from visible light to near IR, in which the highly light trapping mechanism stems from the effective medium theory (EMT) to demonstrate only less than 3% of total reflectance in the range of 500-1100 nm. It also shows conversion efficiency improvement of 20% compared with the planar single-crystalline Si solar cell by the same fabrication processes. The proposed novel photovoltaic device by our core-shell SiNW array revolutionizes the current architecture of solar cells, promising niche points of (1) better absorption, (2) self-antireflection, and (3) low-cost process.