Tailoring the molecular weight of polymer additives for organic semiconductors

Abstract

A binary system comprising both an organic semiconductor and a polymer additive has attracted extensive research interests due to its great potential for use in high-performance, solution-processable electronic devices on flexible substrates. The molecular weight of polymer additives plays a critical role in modulating the crystal growth, enabling phase segregation, optimizing thin film morphology, and improving the charge transport of organic semiconductors. Here, we provide an in-depth review of the recent progress in studying amorphous and semicrystalline polymeric additives, including polystyrene, poly(α-methylstyrene), polymethyl methacrylate, and polyethylene oxide, and fully discuss the effect of the different polymer molecular weights on semiconductor crystallization, active layer composition, and the electrical performance of miscellaneous organic semiconductors. Using the representative examples of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene), 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C₈-BTBT), and 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene (diF-TES-ADT), this work sheds light on utilizing these universal polymers with varying molecular weights to powerfully manipulate the charge transport of other high-mobility, solution-processable organic semiconductors.