Optical and sensing properties of 1-pyrenecarboxylic Acid-functionalized graphene films laminated on polydimethylsiloxane membranes.

We present fabrication and characterization of macroscopic thin films of graphene flakes, which are functionalized with 1-pyrenecarboxylic acid (PCA) and are laminated onto flexible and transparent polydimethylsiloxane (PDMS) membranes. The noncovalently (π-stacked) functionalization of PCA allows us to obtain a number of unique optical and molecular sensing properties that are absent in pristine graphene films, without sacrificing the conducting nature of graphene. The flexible PCA-graphene-PDMS hybrid structure can block 70-95% of ultraviolet (UV) light, while allowing 65% or higher transmittance in the visible region, rendering them potentially useful for a number of flexible UV absorbing/filtering applications. In addition, the electrical resistance of these structures is found to be sensitive to the illumination of visible light, atmospheric pressure change, and the presence of different types of molecular analytes. Owing to their multifunctionality, these hybrid structures have immense potential for the development of versatile, low-cost, flexible, and portable electronic and optoelectronic devices for diverse applications.