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.
