In this study, inorganic silica nanoparticles are used to manipulate the morphology of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS pentacene) thin fi lms and the performance of solution-processed organic thin-fi lm transistors (OTFTs). This approach is taken to control crystal anisotropy, which is the origin of poor consistency in TIPS pentacene based OTFT devices. Thin fi lm active layers are produced by drop-casting mixtures of SiO 2 nanoparticles and TIPS pentacene. The resultant drop-cast fi lms yield improved morphological uniformity at ∼ 10% SiO 2 loading, which also leads to a 3-fold increase in average mobility and nearly 4 times reduction in the ratio of measured mobility standard deviation ( μ Stdev ) to average mobility ( μ Avg ). Grazing-incidence X-ray diffraction, scanning and transmission electron microscopy as well as polarized optical microscopy are used to investigate the nanoparticle-mediated TIPS pentacene crystallization. The experimental results suggest that the SiO 2 nanoparticles mostly aggregate at TIPS pentacene grain boundaries, and 10% nanoparticle concentration effectively reduces the undesirable crystal misorientation without considerably compromising TIPS pentacene crystallinity.

We use 6,13-bis(triisopropylsilylethynyl)pentacene as a model small molecule organic semiconductor and two conjugated polymer additives to demonstrate conjugated polymer-mediated polymorphism of a small molecule organic semiconductor for the first time. The conjugated polymer additives, used with a slow solution crystallization approach, yield crystal structures that are not accessible by nonconjugated polymer additives and impart excellent long-range order. In both of the small molecule semiconductor/conjugated polymer blends studied here, previously unreported polymorphs of a small molecule semiconductor have been identified which also leads to improved charge transport in the absence of external alignment. These results open up a new exciting avenue to manipulate unit cell structure, long-range order, and charge transport of high performance, solution-processed, small molecule organic semiconductors.

Lateral and vertical phase separations play critical roles in the performance of the next-generation organic and hybrid electronic devices. A method is demonstrated here to switch between lateral and vertical phase separations in semiconducting 6,13-bis(triisopropylsilylethynyl) pentacene (TIPSE pentacene)/polymer blend films by simply varying the alkyl length of the polyacrylate polymer component. The phase separation modes depend on intermolecular interactions between small molecule TIPSE pentancene and polymer additives. The blend film with a dominant vertical phase separation exhibits a significant enhancement in average mobility and performance consistency of organic thin-film transistors. V

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Recently, the research in solution-based, small-molecule organic semiconductors has achieved great progress, although their application in organic electronics devices is still restricted by a variety of issues, including crystal misorientation, morphological nonuniformity and low charge-carrier mobility. In order to overcome these issues, hybrid material systems that incorporate both organic semiconductors and additives have been successfully demonstrated to control crystal growth and charge transport of the organic semiconductors. In this work, we first review the recent advances in the charge-carrier mobility of the organic semiconductors, followed by a comparison of the different additives that have been reportedly blended with the semiconductors, including polymeric additives, small-molecule additives and nanoparticle based additives. Then we will review the important nanoparticles employed as additives to blend with solution-based, organic semiconductors, which effectively improved the semiconductor crystallization, enhanced film uniformity and increased charge transport. By discussing specific examples of various well-known organic semiconductors such as 6, 13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene), we demonstrate the essential relationship among the crystal growth, semiconductor morphology, dielectric properties, and chargecarrier mobilities. This work sheds light on the implementation of nanoparticle additives in highperformance organic electronics device application. the application of the organic semiconductor in thin-film transistor and other electronics device fabrication. Throughout the discussion of these specific examples that mainly involve small-molecule organic semiconductors, we showcase that this work can be used to control the crystallization and electrical performance of other newly-discovered, high-performance, semiconducting materials. Advances in organic electronicsIn this section, we will review the various advances in charge-carrier mobilities and device application that have been recently achieved in the field of organic electronics. The following discussion will be mainly focused on various solution-processed, small-molecule, organic semiconductors.The mobilities in solution-processed, small-molecule, organic semiconductors have been reported to be compared to or even far surpass the mobility of amorphous silicon. For example, Asare-Yeboah et al developed a temperature-based method which exposed the substrate to a gradient temperature and induced a solubility difference of a p-type small-molecule semiconductor 6, 13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene) [18]. TIPS pentacene crystals grew from the lower temperature side of the substrate towards the higher temperature side, forming well-aligned ribbons across the whole substrate. A mobility of up to 0.5 cm 2 V −1 s −1 has been reported from the TIPS pentacene OTFTs based on an ITO/PET flexible substrate by using the temperature-based alignment technique. Wade et al demonstrated a zone casting metho...

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