Adding a bulky molecule to the surface of a perovskite might finally make the material stable enough for incorporating into solar panels. Image: Purdue University illustration/Enzheng Shi.Soft and flexible materials called halide perovskites could make solar cells more efficient at significantly lower cost, but they're too unstable to use. A team led by researchers at Purdue University has now found a way to make halide perovskites sufficiently stable by inhibiting the ion movement that makes them rapidly degrade, unlocking their use in solar panels as well as electronic devices.
The discovery, reported in a paper in Nature, also means that halide perovskites can now be stacked together to form heterostructures that would allow a device to perform more functions. The team also included researchers from the Massachusetts Institute of Technology, the University of California, Berkeley, the US Department of Energy's Lawrence Berkeley National Laboratory and Shanghai Tech University in China.
Researchers have already shown that solar cells made out of perovskites in the lab perform just as well as commercial solar cells made of silicon. Perovskites have the potential to be even more efficient than silicon because they waste less energy when converting solar energy to electricity. And because perovskites can be processed from a solution into a thin film, like ink printed on paper, they could be produced more cheaply and in higher quantities than silicon-based solar cells.
"There have been 60 years of a concerted effort making good silicon devices. There may have been only 10 years of concerted effort on perovskites and they're already as good as silicon, but they don't last," said Letian Dou, an assistant professor of chemical engineering at Purdue University.
A perovskite is made up of components that an engineer can individually replace at the nanometer scale to tune the material's properties. Including multiple perovskites in a solar cell or integrated circuit would allow the device to perform different functions, but perovskites are too unstable to stack together.
Dou's team discovered that simply adding a rigid, bulky molecule called bithiophenylethylammonium to the surface of a perovskite stabilizes the movement of ions, preventing the chemical bonds from breaking easily. The researchers also demonstrated that adding this molecule makes a perovskite stable enough to form clean atomic junctions with other perovskites, allowing them to be stacked together and integrated.
"If an engineer wanted to combine the best parts about perovskite A with the best parts about perovskite B, that typically can't happen because the perovskites would just mix together," said Brett Savoie, an assistant professor of chemical engineering at Purdue University, who conducted simulations explaining what the experiments revealed on a chemical level. "In this case, you really can get the best of A and B in a single material. That is completely unheard of."
The bulky molecule allows a perovskite to stay stable even when heated to 100°C. Solar cells and electronic devices require elevated temperatures of 50–80°C to operate.
These findings also mean that it could be possible to incorporate perovskites into computer chips, the researchers said. Tiny switches in computer chips, called transistors, rely on tiny junctions to control electrical current. A pattern of perovskites might allow the chip to perform more functions than possible with just one material.
This story is adapted from material from Purdue University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.