Scientists at Rice University have developed a simpler way to change plain silicon into valuable black silicon by using the top electrode as the catalyst. Gold electrodes serve as the catalyst in this new process which will benefit solar cell manufacture.
Black silicon reflects little light and allows more to reach the active elements of solar cells to be turned into electricity. The texture of black silicon allows the efficient collection of light from any angle, at any time of day. This new manufacturing technique should push black silicon closer to commercialization.
Rice lab of chemist Andrew Barron noted this work led by Rice postdoctoral researcher Yen-Tien Lu has two major attractions. “One, removing steps from the process is always good,” he said. “Two, this is the first time in which metallization is a catalyst for a reaction that occurs several millimeters away.”
Barron said the metal layer used as a top electrode is usually applied last in solar cell manufacturing. The new method known as contact-assisted chemical etching applies the set of thin gold lines that serve as the electrode earlier in the process, which also eliminates the need to remove used catalyst particles.
An extremely thin layer of gold atop titanium, which bonds well with both gold and silicon, should be an effective electrode that also serves for catalysis. “The trick is to etch the valleys deep enough to eliminate the reflection of sunlight while not going so deep that you cause a short circuit in the cell,” he said.
He said the electrode’s ability to act as a catalyst suggests other electronic manufacturing processes may benefit from a bit of shuffling.
“Metal contacts are normally put down last,” Barron said. “It begs the question for a lot of processes of whether to put the contact down earlier and use it to do the chemistry for the rest of the process.”