Temperature-Dependent Mechanical Properties of Organic Semiconductors

Rationalizing the deformation of molecular and polymer-based organic semiconductors (OSC) under mechanical stress across a range of operating temperatures is critical both to the development of OSC for flexible devices and to a more general understanding of the degradation of OSC performance. Here, we develop and deploy atomistic molecular dynamics simulations to determine stress-strain relationships of molecular (i.e., non-fullerene and fullerene acceptors) and polymer (i.e., P3HT)-based OSC of interest for organic solar cells. A key goal of this work is to clarify how changes in chemical structure of the OSC building blocks, packing configurations, polymer chain entanglement, and both local and long-range material order (e.g., torsional disorder, crystallinity, etc.) influence properties such as the elastic modulus. By making connections with other (thermo)mechanical and optoelectronic works in the literature, the results discussed here seek to provide insights into upper and lower temperature limits for OSC during device operation and overall material stability.