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    Ultrasoft and High-Mobility Block Copolymers for Skin-Compatible Electronics
    (Weinheim : Wiley-VCH, 2020) Ditte, Kristina; Perez, Jonathan; Chae, Soosang; Hambsch, Mike; Al-Hussein, Mahmoud; Komber, Hartmut; Formanek, Peter; Mannsfeld, Stefan C.B.; Fery, Andreas; Kiriy, Anton; Lissel, Franziska
    Polymer semiconductors (PSCs) are an essential component of organic field-effect transistors (OFETs), but their potential for stretchable electronics is limited by their brittleness and failure susceptibility upon strain. Herein, a covalent connection of two state-of-the-art polymers—semiconducting poly-diketo-pyrrolopyrrole-thienothiophene (PDPP-TT) and elastomeric poly(dimethylsiloxane) (PDMS)—in a single triblock copolymer (TBC) chain is reported, which enables high charge carrier mobility and low modulus in one system. Three TBCs containing up to 65 wt% PDMS were obtained, and the TBC with 65 wt% PDMS content exhibits mobilities up to 0.1 cm2 V−1 s−1, in the range of the fully conjugated reference polymer PDPP-TT (0.7 cm2 V−1 s−1). The TBC is ultrasoft with a low elastic modulus (5 MPa) in the range of mammalian tissue. The TBC exhibits an excellent stretchability and extraordinary durability, fully maintaining the initial electric conductivity in a doped state after 1500 cycles to 50% strain. © 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH
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    Analysis of the Annealing Budget of Metal Oxide Thin-Film Transistors Prepared by an Aqueous Blade-Coating Process
    (Weinheim : Wiley-VCH, 2022) Tang, Tianyu; Dacha, Preetam; Haase, Katherina; Kreß, Joshua; Hänisch, Christian; Perez, Jonathan; Krupskaya, Yulia; Tahn, Alexander; Pohl, Darius; Schneider, Sebastian; Talnack, Felix; Hambsch, Mike; Reineke, Sebastian; Vaynzof, Yana; Mannsfeld, Stefan C. B.
    Metal oxide (MO) semiconductors are widely used in electronic devices due to their high optical transmittance and promising electrical performance. This work describes the advancement toward an eco-friendly, streamlined method for preparing thin-film transistors (TFTs) via a pure water-solution blade-coating process with focus on a low thermal budget. Low temperature and rapid annealing of triple-coated indium oxide thin-film transistors (3C-TFTs) and indium oxide/zinc oxide/indium oxide thin-film transistors (IZI-TFTs) on a 300 nm SiO2 gate dielectric at 300 °C for only 60 s yields devices with an average field effect mobility of 10.7 and 13.8 cm2 V−1 s−1, respectively. The devices show an excellent on/off ratio (>106), and a threshold voltage close to 0 V when measured in air. Flexible MO-TFTs on polyimide substrates with AlOx dielectrics fabricated by rapid annealing treatment can achieve a remarkable mobility of over 10 cm2 V−1 s−1 at low operating voltage. When using a longer post-coating annealing period of 20 min, high-performance 3C-TFTs (over 18 cm2 V−1 s−1) and IZI-TFTs (over 38 cm2 V−1 s−1) using MO semiconductor layers annealed at 300 °C are achieved.
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    Charge Carrier Mobility Improvement in Diketopyrrolopyrrole Block-Copolymers by Shear Coating
    (Basel : MDPI, 2021) Ditte, Kristina; Kiriy, Nataliya; Perez, Jonathan; Hambsch, Mike; Mannsfeld, Stefan C.B.; Krupskaya, Yulia; Maragani, Ramesh; Voit, Brigitte; Lissel, Franziska
    Shear coating is a promising deposition method for upscaling device fabrication and enabling high throughput, and is furthermore suitable for translating to roll-to-roll processing. Although common polymer semiconductors (PSCs) are solution processible, they are still prone to mechanical failure upon stretching, limiting applications in e.g., electronic skin and health monitoring. Progress made towards mechanically compliant PSCs, e.g., the incorporation of soft segments into the polymer backbone, could not only allow such applications, but also benefit advanced fabrication methods, like roll-to-roll printing on flexible substrates, to produce the targeted devices. Tri-block copolymers (TBCs), consisting of an inner rigid semiconducting poly-diketo-pyrrolopyrrole-thienothiophene (PDPP-TT) block flanked by two soft elastomeric poly(dimethylsiloxane) (PDMS) chains, maintain good charge transport properties, while being mechanically soft and flexible. Potentially aiming at the fabrication of TBC-based wearable electronics by means of cost-efficient and scalable deposition methods (e.g., blade-coating), a tolerance of the electrical performance of the TBCs to the shear speed was investigated. Herein, we demonstrate that such TBCs can be deposited at high shear speeds (film formation up to a speed of 10 mm s−1). While such high speeds result in increased film thickness, no degradation of the electrical performance was observed, as was frequently reported for polymer−based OFETs. Instead, high shear speeds even led to a small improvement in the electrical performance: mobility increased from 0.06 cm2 V−1 s−1 at 0.5 mm s−1 to 0.16 cm2 V−1 s−1 at 7 mm s−1 for the TBC with 24 wt% PDMS, and for the TBC containing 37 wt% PDMS from 0.05 cm2 V−1 s−1 at 0.5 mm s−1 to 0.13 cm2 V−1 s−1 at 7 mm s−1. Interestingly, the improvement of mobility is not accompanied by any significant changes in morphology.