Ultraviolet light alters the conductance of organic molecules deposited on graphene, and could be used to manipulate devices that operate on molecular scales.

Molecular electronics hold promise for making computer chips smaller, but researchers have struggled to control the electrical behaviour of individual molecules. To address this problem, Xuefeng Guo and Zhongfan Liu at Peking University in Beijing and their colleagues used derivatives of diarylethene molecules, which change shape when exposed to light. This changes how electrons pass through the molecules and so alters conductivity. These 'single-molecule junctions' functioned reproducibly as electrical switches.

Angew. Chem. Int. Edn. http://dx.doi.org/10.1002/anie.201304301 (2013)