One step to solar cell efficiency

Thu, 06/19/2014 - 12:42pm
Mike Williams, Rice Univ.

Rice Univ. scientists have reduced to one step the process to turn silicon wafers into the black silicon used in solar cells. The advance could cut costs associated with the production of solar cells. Here, a cross section shows inverted pyramids etched into silicon by a chemical mixture over eight hours. Image: Barron Group/Rice Univ.Rice Univ. scientists have created a one-step process for producing highly efficient materials that let the maximum amount of sunlight reach a solar cell.

The Rice laboratory of chemist Andrew Barron found a simple way to etch nanoscale spikes into silicon that allows more than 99% of sunlight to reach the cells’ active elements, where it can be turned into electricity.

The research by Barron and Rice graduate student and lead author Yen-Tien Lu appears in the Journal of Materials Chemistry A.



Barron and Lu have replaced a two-step process that involved metal deposition and electroless chemical etching with a single step that works at room temperature.

The chemical stew that makes it possible is a mix of copper nitrate, phosphorous acid, hydrogen fluoride and water. When applied to a silicon wafer, the phosphorous acid reduces the copper ions to copper nanoparticles. The nanoparticles attract electrons from the silicon wafer’s surface, oxidizing it and allowing hydrogen fluoride to burn inverted pyramid-shaped nanopores into the silicon.

Fine-tuning the process resulted in a black silicon layer with pores as small as 590 nm that let through more than 99% of light. (By comparison, a clean, un-etched silicon wafer reflects nearly 100% of light.)

Barron said the spikes would still require a coating to protect them from the elements, and his lab is working on ways to shorten the eight-hour process needed to perform the etching in the laboratory. But the ease of creating black silicon in one step makes it far more practical than previous methods, he said.

Source: Rice Univ.


Share This Story

The password field is case sensitive.