Carbon nanotubes-photochromic polymer blends: Light-triggered conductance switching device

We demonstrate an easy and scalable way to get devices in which the electrical resistance can be tuned by UV/visible light exposure. In particular, such a feature is based on photochromic diarylethene polymer - carbon nanotubes blend where reversible light controlled switching of the photochromic component induces a change in the electrical conductivity of the material. Differently from the single molecule approach, we use a simple ‘wet-chemistry method’ to obtain a net of carbon nanotubes embedded in a photochromic polymer. When the device is illuminated with UV light, a decreasing in the electric resistance of the active layer occurs. A resistance modulation up to 300% of the initial value is achieved, which is completely reversible with visible light illumination. The process is repeatable many times with a good fatigue resistance at room conditions. Supported by electrical and spectroscopic evidences, we show that the light-triggered electrocyclization of the polymer affects the inter-tube charge mobility, resulting in large overall change in the resistance of the device.