Photoswitchable chromic behavior of conjugated polymer films for reversible patterning and construction of a logic gate

Photoswitchable fluorescent films were constructed using a conjugated polymer as a fluorescence-color changeable unit and a photochromic molecule as a phototriggered, selectively energy-accepting component. The conjugated polymer was synthesized to have an electron donor-acceptor structure in the main chain, which could emit dual fluorescence colors (blue and green), in which a thienopyrazine unit was introduced as an electron acceptor. When UV light was irradiated on the composite film containing the polymer and photochrome, its emission color changed from green to blue or to red because the initial green emission was absorbed by the photoisomers of the photochromes. These photoinduced emission color changes of the polymer films could be utilized in erasable imaging and interpreted as a combined logic operation, which is important for the construction of more complex molecular devices through the integration of molecular components. The results indicated that a combined logic system was successfully accomplished based on the composite films containing the conjugated polymer and photochrome in the absence and presence of UV light.