Conjugated Polymer Patterning through Photooxidative Backbone Cleavage

Photolithographic patterning of a xanthate precursor to poly(3,4‐diphenyl‐2,5‐thienylene vinylene) is described. Unlike xanthate precursors to poly(p‐phenylene vinylene), the thienylene vinylene analogue patterns as a positive tone resist. Characterization of irradiated films reveals photooxidative cleavage of the vinylene linker decreases the molecular weight of the polymer (increasing the solubility of the UV‐exposed areas). As a result of the mechanism, the developed pattern sees no UV light exposure, which is a significant advantage compared with negative‐tone‐conjugated polymer resists. Single micron resolution of a low‐bandgap polymer is achieved in an efficient and scalable process. A xanthate precursor to poly(3,4‐diphenyl‐2,5‐thienylene vinylene) is shown to photopattern as a positive tone resist. Photooxidative cleavage of the polymer backbone increases the solubility of the light‐exposed areas, allowing for pattern formation. Single micrometer resolution of an insoluble active material is achieved without compromise to the polymer's properties.