Direct Inkjet Printing of TIPS-Pentacene Single Crystals onto Interdigitated Electrodes by Chemical Confinement

Organic semiconducting single crystals (OSSCs) are very promising for low-cost electronics, being the highest performers among organic semiconductors in terms of charge transport, with carrier mobilities exceeding 10 cm2 V s-1. Here, it is demonstrated how it is possible to obtain millimeter-long single crystals of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) onto gold interdigitated electrodes patterned onto flexible plastic substrates, via direct inkjet printing of precursor solutions. This result is enabled by a novel chemical confinement strategy that exploits fluorinated thiols as solvophobic "chemical fences", able to avoid the printed solution spreading, thus promoting the formation of single crystals even on highly heterogeneous surfaces, without changing the chemical nature of the surface underlying the grown crystals. Electrical measurements demonstrate a good electrical contact with the electrodes. Moreover, their response UV-vis (Ultraviolet-visible) is among the highest up to now reported for organic UV-vis photodetectors, and their performance as direct X-ray detectors is satisfactory, confirming that the printed crystals have an effective electrical contact with the underlying electrodes. Since both the solvophobic fence and the TIPS crystals precursor solution are inkjet printed on flexible substrates, this work opens novel perspectives for the practical use of OSSCs in low cost, yet performing, flexible electronics.