Elucidating Multiscale Phenomena that Determine the Thermomechanical Response of Organic Semiconductors

On-demand manufacturing of (ultra)flexible electronics that make use of organic semiconductors (OS) requires detailed understanding of processing-morphology-property characteristics. While there has been significant effort to determine these relationships for OS electronic, optical, and redox properties, there remains a need to address these relationships for OS thermal and mechanical response. Here, we develop and implement molecular dynamics (MD) simulations to determine the multiscale thermomechanical response of OS. Specifically, we establish the effects that temperature has on the mechanical response of (dis)ordered domains in a π-conjugated homopolymer and across a series of non-fullerene molecular acceptors. These polymeric and molecular classes of OS find application in organic photovoltaics, displays, and sensors, among others. Key figures of merit include the Young’s modulus and Poisson’s ratio. In addition, chain entanglements, orientation, and molecular diffusivity are considered. The multiscale understanding provided here presents new insights to synthetically control OS thermomechanical response in the quest for mechanically robust and manufacture-scale flexible electronics.