Soft and flexible materials called halide perovskites could make solar cells more efficient at significantly less cost but they’re too unstable to use. A research team has found a way to make halide perovskites stable enough by inhibiting the ion movement that makes them rapidly degrade, unlocking their use for solar panels as well as electronic devices. The discovery also means that halide perovskites can stack together to form heterostructures that would allow a device to perform more functions.
Solar cells made out of perovskites in the lab perform just as well as the solar cells on the market made of silicon. Perovskites have the potential to be even more efficient than silicon because less energy is wasted 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 more cheaply produced in higher quantities compared to silicon.
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.
Simply by adding a rigid, bulky molecule called bithiophenylethylammonium to the surface of a perovskite stabilizes the movement of ions, preventing 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 stack and integrate.
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. It could also be possible to incorporate perovskites into computer chips. 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 with just one material.