Quickly transferring energy from one place to another—without loss—could fundamentally change solar panels and computers. Materials made from long chains of tiny particles, or nanoparticles, show promise for such energy transfer. However, going even smaller than nano-dimensions hasn’t worked quite as planned. Researchers suspected the particles needed to be close to each other to transfer energy efficiently. Now, a team has shown that the particles can be too close. Specifically, the energy transfer drops dramatically when the particles in the chain are less than a nanometer apart.