Light-controlled resistance modulation in a photochromic diarylethene-carbon nanotube blend

Photochromic molecules are part of a large class of materials in which light stimulus not only induces a color variation but also affects other physicochemical properties. However, the change of bulk electrical properties (e.g., electrical conductivity) via light excitation remains difficult to control because the intrinsically switchable molecules may lose their functionality when wired with conductive electrodes. In contrast with previous work based on single molecules, here we demonstrate a facile and accessible “wet-chemical” method to produce light-induced electrical switching. The electrical conductivity of a photochromic blend composed of diarylethene polymer and single-walled carbon nanotubes (SWNTs) is reversibly tuned according with UV−vis excitation. The devices present good thermal stability and remarkable fatigue resistance under ambient conditions. Supported by electrical and spectroscopic evidence, we show that the intertube electrical coupling, mediated by the light-induced electrocyclization of the diarylethene unit, is the mechanism responsible for the modulation.