A class of crystals called perovskites are a hot research topic, because they are inexpensive and display excellent electrical properties. They could potentially be used to make solar cells that are both cheaper and more efficient than the silicon cells that dominate today’s solar industry. Now, scientists at Stanford University have discovered that when perovskites are squeezed, they become more electrically conductive. Better yet, applying pressure to the perovskites allowed scientists to tune them in a predictable way. In fact, the changes were visible.
To understand exactly how perovskites behave under pressure, the scientists placed the crystals in a vice between two diamonds. As the diamonds were squeezed closer together, the perovskite samples changed color. These lab results indicate that perovskites can absorb high or low energy light waves, depending on the precise amount of pressure that is applied.
By tracking the positions of atoms upon compression using X-ray diffraction, we can explain exactly how the materials’ structure responds to pressure. Overall, this work shows that pressure is a tuning knob for improving the properties of perovskite absorbers in a predictable way.