Binary solvent engineering for small-molecular organic semiconductor crystallization

Solution processed, flexible electronics has garnered great research attention in the last decade, and has found promising applications in semiconductor device fabrication such as in thin film transistors and organic gas sensors. Binary solvents have been demonstrated to exert an important impact on the semiconductor dissolution, crystal growth, phase segregation, film morphology, crystal alignment, film crystallinity and charge transport of organic semiconductors. In this article, we conducted a comprehensive review on the effect of engineering binary solvents on the crystallization of organic semiconductors. By studying the organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene as a representative example, we showcase that the optimization of solvent choices can play a vital role in modulating the solvent evaporation, intermolecular interaction, supramolecular aggregation, semiconductor nuclei, crystal orientation and charge carrier mobilities. Based on a detailed review of these important works, we wish to shed light on the great potential of fine-tuning the solvent choices in order to optimize the charge transport and electrical performance of flexible electronic devices.