In organic photovoltaic devices, the active layer must simultaneously be thin enough that the electrons and holes can easily be collected, yet thick enough to absorb much of the solar radiation landing upon it. In an article published recently in Nature Photonics, a Princeton team has come up with an ingenious solution to this conundrum.

Stephanie Lee, working with Professor Yueh-Lin Loo and others, has studied large two-dimensional spherulites of the organic semiconductor TES-ADT, and found that the mobilities of transistors are surprisingly independent of the general pi-stacking direction, due to the low-angle grain boundaries that are ubiquitous in spherulites.

A team led by Rodney D. Priestley has demonstrated the formation of ultrastable glassy polymer films, as reported in the April issue of the journal Nature Materials.