Computational Insights into the Thermophysical, Conformational and Electronic Properties of Diketopyrrolopyrrole and Isoindigo Based Semiconducting Polymers

Semiconducting polymers, driving the leading edge of organic electronics and emerging soft technologies, feature a range of key attributes including broad solubility for large-scale solution deposition and charge transport properties comparable to amorphous silicon. The optoelectronic and thermomechanical properties of these π-conjugated materials are fully controllable and tunable through synthetic design, continuously improving organic electronics; however, although semiconducting polymers offer multiple functionalization sites for derivatization, synthetic optimization can be time-consuming and costly. Additionally, minor structural changes, such as altering one carbon in the polymer sidechains or the nature of an aryl group in the repeating unit, can significantly affect their electronic or mechanical properties, positively or negatively. To accelerate and enhance the development of semiconducting materials and to predict their properties before synthesis, computational chemistry serves as a valuable tool. Recent advancements in computing power and algorithm availability have made this increasingly feasible. In this work, we investigate and determine key thermomechanical properties, including glass transition temperatures and persistence lengths, of high-performance donor-acceptor conjugated polymers based on diketopyrrolopyrrole and isoindigo using in silico methods. This study not only provides insights into the molecular mechanisms underlying trends in thermomechanical properties, but also discusses the limitations and advantages of the computational methods. Overall, our work demonstrates that computational methods are an effective and powerful tool for identifying potential design targets and for understanding and rationalizing trends in semiconducting polymers and related emerging electronic devices.