Advancing Semiconducting Polymer Patterning: Photothermal Approach for Sub-Micron Feature Fabrication for Electronic photodetector

The industrial development of Semiconducting Polymers (SPs) faces a significant hurdle in the absence of an inexpensive, rapid, and viable patterning technology capable of producing sub-micron features. In this study, we explore Photothermal Patterning as a promising technique that leverages the solubility characteristics of SPs to address this challenge. The Photothermal Patterning process involves exposing an SP film to a semi-poor solvent mixture, rendering the polymer insoluble at room temperature. Subsequently, the SP film is exposed to laser radiation at a wavelength that is strongly absorbed by the SP in its solid state. The absorption of photons leads to localized heating, causing the SP to dissolve once the temperature surpasses its dissolution threshold, resulting in the formation of negative patterns. To validate the feasibility of this approach, we conducted experiments using the Alvéole PRIMO, a commercially available cleanroom equipment. Additionally, we developed a quasi-steady state model to investigate the dissolution behavior of SPs in solvent mixtures induced by a Gaussian laser beam's heating effect. Through our analysis, we successfully determined the depth and width of the patterns obtained and identified the influence of solubility kinetics on heat transfer dynamics. By gaining a comprehensive understanding of the heat transfer effects, we have been able to identify the regime in which these effects dominate, thereby enabling us to modify the shape of the patterns obtained. Leveraging this knowledge, we aim to employ the Photothermal Patterning technique to fabricate P3HT patterns over gold electrodes, with the goal of obtaining a functional NIR photodetector. This research significantly contributes to the development of a cost-effective and rapid patterning technology for SPs, opening up new possibilities for their industrial applications in the field of electronic devices.