Direct Characterization of Mechanical Properties in Fully Free-Standing Polymeric Electronic Films for Stretchable Devices

The mechanical properties of polymeric electronic films are fundamental to their performance in stretchable and flexible electronics, where materials must retain functionality under mechanical deformation. Common methods for evaluating these properties, such as film-on-elastomer and film-on-water, provide valuable insights but may introduce substrate-induced effects. To address this limitation, we present a novel method (FAST) for directly probing the mechanical response of fully free-standing polymeric electronic films. Our study systematically examines how film thickness, geometric dimensions, and temperature affect the mechanical behavior of ultrathin films of a crystalline polymer semiconductor (i.e., P3PT). To validate the robustness and versatility of this method, we extend the analysis to other conjugated polymers, including the semicrystalline polymer semiconductor PDPP3T, the semiparacrystalline polymer semiconductor PM6, and the nearly amorphous polymer semiconductor IDTBT. Additional cross-validation with two polymer semiconductors (polythiophene, IDTBT) and the insulating polymer SEBS across varying thicknesses further underscores the robustness of this method. By eliminating substrate interference, this approach enables an accurate assessment of the intrinsic mechanical properties of free-standing ultrathin films, offering deeper insights into their behavior under practical conditions. The insights gained contribute to the advancement of materials characterization techniques, advancing our understanding of the mechanical behavior of polymeric films, and inform the design of next-generation flexible and wearable electronic devices.