In the continuing quest for flex – as in flexible solar panels – the latest advance could make it super easy to put a solar cell on anything from paper to windows.
True, in the past solar panels have been integrated into jackets, ski helmets and messenger bags. These noble but usually clumsy efforts haven’t really taken off, however, as evidenced by the fate of Konarka, the bankrupt Massachusetts company whose quite-nifty pliable solar material won it big venture capital backing – and even support from the state’s severely conservative governor – but apparently not enough customers.
But great leaps forward could be taking place. Earlier this month, an international team of researchers wrote up a technique for constructing fiber-based solar cells that could yield “portable, foldable, even wearable” photovoltaics.
And now comes peel-and-stick solar.
As reported in the journal Scientific Reports, a team led by Stanford University scientists found a way to do something simply that had long been excruciatingly difficult: to fabricate potentially flexible thin-film solar cells on something other than rigid silicon and glass substrate. Their solution overcame the issue of flexible alternatives to silicon and glass having “poor surface flatness and low tolerance to high temperature and chemical processing.” As Stanford explained in a press release:
The new process involves a unique silicon, silicon dioxide and metal “sandwich.” First, a 300-nanometer film of nickel (Ni) is deposited on a silicon/silicon dioxide (Si/SiO2) wafer. Thin-film solar cells are then deposited on the nickel layer utilizing standard fabrication techniques, and covered with a layer of protective polymer. A thermal release tape is then attached to the top of the thin-film solar cells to augment their transfer off of the production wafer and onto a new substrate.
From there, the fully fabricated thin-film solar cell can be peeled off. It’s not a DIY process, mind you, involving a water bath at precise temperature and other careful manipulations, but it doesn’t require any expensive materials or processes. Once done, the solar cell, with its original efficiency of 7.5 percent intact, can be attached to “virtually any substrates regardless of materials, flatness and rigidness,” the researchers said. (And that silicon wafer is good to go for reuse.)
Stanford noted that this isn’t first time thin-film cells have been paired with flexible substrates – but it could be a breakthrough in its simplicity.
“The main contribution of our work is that we have done so without modifying any existing processes, facilities or materials, making them viable commercially. And we have demonstrated our process on a more diverse array of substrates than ever before,” Chi Hwan Lee, lead author of the paper and a PhD candidate in mechanical engineering, said in a statement.
“Now you can put them on helmets, cell phones, convex windows, portable electronic devices, curved roofs, clothing – virtually anything,” colleague Xiaolin Zheng added.