Ordered polymers emit single photons.

Molecules of the semiconducting polymer MEH-PPV, commonly used in light-emitting diodes, have been shown to act as efficient single photon emitters when forced to adopt an ordered conformation. Researchers at the Oak Ridge National Laboratory in the U.S. isolated a single polymer chain in a micro-droplet and deposited it on a glass surface. The chain acquired negative charge during droplet formation, and, thanks to random negative charges on the glass, aligned perpendicular to its surface. Each MEH-PPV chain has 100 or more light-emitting units, or chromophores, along its length, and when multiple chains were deposited parallel to each other the highly ordered arrangement resulted in efficient energy transfer between them.