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Item type:Publication, Access status: without files , Charge carrier mobility improvement in diketopyrrolopyrrole block‐copolymers by shear coating(2021-05-01); ; ; ; 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.Publicationtype: Journal Article16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ultrasoft and High-Mobility Block Copolymers for Skin-Compatible Electronics(2021-01-27); ; ; ; 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.Publicationtype: Journal ArticleScopus© Citations 50 22 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Sequentially processed P3HT/CN6-CP•−NBu4+ films: interfacial or bulk doping?(Wiley-VCH, 2020-04-13); ; ; ; Derivatives of the hexacyano-[3]-radialene anion radical (CN6-CP•−) emerge as a promising new family of p-dopants having a doping strength comparable to that of archetypical dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ). Here, mixed solution (MxS) and sequential processing (SqP) doping methods are compared by using a model semiconductor poly(3-hexylthiophene) (P3HT) and the dopant CN6-CP•−NBu4+ (NBu4+ = tetrabutylammonium). MxS films show a moderate yet thickness-independent conductivity of ≈0.1 S cm−1. For the SqP case, the highest conductivity value of ≈6 S cm−1 is achieved for the thinnest (1.5–3 nm) films whereas conductivity drops two orders of magnitudes for 100 times thicker films. These results are explained in terms of an interfacial doping mechanism realized in the SqP films, where only layers close to the P3HT/dopant interface are doped efficiently, whereas internal P3HT layers remain essentially undoped. This structure is in agreement with transmission electron microscopy, atomic force microscopy, and Kelvin probe force microscopy results. The temperature-dependent conductivity measurements reveal a lower activation energy for charge carriers in SqP samples than in MxS films (79 meV vs 110 meV), which could be a reason for their superior conductivity.Publicationtype: Journal ArticleScopus© Citations 7 27 59 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Synthesis and characterization of a semiconducting and solution-processable ruthenium-based polymetallayne(2020-01-14); ; ; ; Polymetallaynes are a special class of Wolf type-III polymers with high potential in organic electronics, especially in applications such as OFET, OLED and OPV. However, almost all reported polymetallaynes contain group 10 metals, while functional polymetallaynes with earlier transition metals have rarely been reported. Here, different synthetic routes to a group 8 polymetallayne P[Ru(dppe)2-DDBT], containing Ru(ii) centers bridged in the trans-position by the organic linker 3,3′-didodecyl-5,5′-diethynyl-2,2′-bithiophene (DDBT), are explored. The polymer is obtained by copper-free dehydrohalogenation, characterized using NMR, IR and UV-vis spectroscopy, MALDI-TOF-MS, GPC and CV. In solution, CV studies show two separated metal-centered redox processes, indicating that the charge between metal centers is delocalized via the bridging ligand and a mixed-valence species exists (Kc = 102). In thin-films, P[Ru(dppe)2-DDBT] exhibits a single oxidation wave with a higher peak current intensity, consistent with a two-electron process and localized charge. Despite a degree of polymerization ∼32 based on NMR and GPC studies, P[Ru(dppe)2-DDBT] is fully solution processable, and thin-films were obtained via spin-coating using different solvents. AFM investigations of the films showed very low surface roughness, and first OFET devices with a top-gate bottom-contact (TGBC) architecture were fabricated to characterize the electronic properties, confirming the semiconducting behaviour of the polymetallayne.Publicationtype: Journal Article21 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Layer-by-layer assembly enabled by the anionic p-dopant CN6-CP•-K+: a route to achieve interfacial doping of organic semiconductorsHighly efficient 2D (interfacial) doping of organic semiconductors, poly(3-hexylthiophene) (P3HT) and TIPS-pentacene, was achieved by a polyelectrolyte-supported layer-by-layer assembly of the dual-mode functional dopant CN6-CP•-K+, having an anionic group for its fixation onto oppositely charged surfaces/molecules as well as electron-deficient groups providing its p-doping ability. Polyelectrolyte-supported dopant layers were used to generate conductive channels at the bottom or at the top of semiconducting films. Unlike to the case of sequentially processed P3HT films doped by F4TCNQ (Moulé, J. Chem. Mater. 2015, 27, 5765; Koech, P. K. J. Mater. Chem. C 2013, 1, 1876; Schwartz, B. J. J. Phys. Chem. Lett. 2015, 6, 4786), the use of more polar CN6-CP•-K+ dopant and ultrathin polycation separation interlayer enables predominantly interfacial kind of doping placement with no or minimal intercalation of the dopant into the semiconductor bulk. The layered structure of the doped film was proved by transmission electron microscopy of the cross-section and it agrees well with other data obtained in this work. The interfacial doping enabled an impressive conductivity of 13 S/cm even for ultrathin P3HT films. We propose to explain the superior efficiency of the interfacial doping compared to the bulk doping in terms of unperturbed morphology of the semiconductor and high mobility of charge carriers, which are spatially separated from the dopant phase.Publicationtype: Journal ArticleScopus© Citations 6 24