01 / 04
02 / 04
03 / 04
04 / 04
A silver wafer reflects the face of NREL research scientist Hao-Chih Yuan, before the wafer is washed with a mix of acids. The acids etch holes, absorbing light and turning the wafer black.
Hao-Chih Yaun pours the final mixture, a combination of hydrofluoric acid and hydrogen peroxide — onto the silicon wafer inside a protective glass box at NREL's Solar Energy Research Facility.
The process takes just three minutes at room temperature. Inside a laboratory at NREL's Solar Energy Research Facility, an acid mixture bubbles atop a silicon wafer as it etches holes and works toward turning the wafer black.
Howard Branz, front row, center, is the principal investigator for the team that won an R&D 100 Award for a new "black silicon" process to improve the efficiency of solar cells.