A Sturdy Electrode Coating: To operate efficiently, organic devices—such as light-emitting diodes—require electrodes that emit or take up electrons at low applied voltages (that is, have low work functions). Often these electrodes are metals, such as calcium, that are not stable in air or water vapor and have to be protected from environmental damage. Zhou et al. (p. 327 ; see the Perspective by Helander ) report that a coating polymer containing aliphatic amine groups can lower the work functions of various types of electrodes by up to 1.7 electron volts and can be used in a variety of devices.

Organic photovoltaics, the technology to convert sun light into electricity by employing thin films of organic semiconductors, has been the subject of active research over the past 20 years and has received increased interest in recent years by the industrial sector. This technology has the potential to spawn a new generation of low-cost, solar-powered products with thin and flexible form factors. Here, we introduce the energy and environmental science community to the basic concepts of organic photovoltaics and discuss some recent science and engineering results and future challenges.