Flexible electronics are often sold on a simple promise: bendable screens, lightweight solar cells or wearable devices that can bend and flex without breaking. But what does that "flexibility" actually look like at the molecular scale, and how does it affect performance? Researchers led by the University of Cambridge say they have taken a first step towards answering this question. Using ultra-sensitive atomic force microscopy—which analyzes materials by "feeling" them—the researchers were able to measure how stiff flexible semiconductor molecules are when packed together, down to the scale of just a few molecules.