Enhanced Absorption in the Wide Wavelength Range: Black Silicon Decorated with Few-Layer PtS₂

Ultrablack materials are distinguished by their extremely low reflectivity and high absorptivity, which can be used to increase photovoltaic cell efficiency, capture stray light, and design radar camouflage. Black silicon is a type of ultrablack material, the absorptivity of which still has room for improvement. Here, nanostructured black silicon is prepared by a metal-assisted chemical etching method, in which chloroauric acid (HAuCl₄) acts as the catalyst. Furthermore, the study demonstrates that due to the deposition of a few layers of PtS₂ the number of “hot spots” between the sidewall gaps of bamboo shoot-like protrusions is significantly increased, thereby further improving the absorption of black silicon and enhancing light suppression. The few-layer PtS₂ was densely grown on the black silicon by combining the physical vapor deposition (PVD) and the chemical vapor deposition (CVD) methods. Next, the enhanced Raman property of black silicon was explored. These results provide a new idea for the manufacture of excellent photovoltaic and optoelectronic devices in which very high absorption is necessary.