record values exceeding 10 cm 2 V −1 s −1 have been reported. [3][4][5][6][7][8] Though these results are promising, some of these reported values suffer from overestimation, [9,10] require significant engineering efforts, [3] complex fabrication procedures, [4] or employ nonscalable fabrication techniques, [5] ultimately highlighting the need for alternative and potentially more industry-relevant processing methods. We believe that adjustments to existing solution coating methods rather than intensive technology engineering could result in a feasible and simple approach.Ink properties such as the solvents' boiling point, [11] solubility parameters, [12] or the solute concentration [13] can be tuned in order to control crystal growth and packing in a manner that provides favorable electrical characteristics. Such ink engineering has recently been shown to generate high mobility devices based on C8-BTBT. [14] In particular, a distinct increase of performance by utilizing a solvent mixture rather than a single solvent has been reported for a range of semiconductors, including TIPS-pentacene [15,16] or diketopyrrolopyrrole (DPP)-based polymers. [17] This approach has frequently been combined with another effective method -the addition of a polymer additive to the printing solution. This combination has been shown to significantly reduce the device-to-device variations and yielded improved transistor performances when applied to high-mobility small molecules, like TIPS-pentacene, [18] diF-TES-ADT, [8,19,20] or even C8-BTBT. [5,7,21,22] In this study, we explore various blends of the high-mobility semiconductor C8-BTBT with the inert polymer polystyrene (PS) with the objective of improving device-to-device uniformity and investigating the effect on device characteristics. We report improved film formation that results in the reduction of deviceto-device variations and the reliable fabrication of high-mobility organic field-effect transistors by a scalable, meniscus-guided coating method, and demonstrate OFETs based on C8-BTBT, that to the best of our knowledge show the highest intrinsic mobility so far reported. Results and Discussion Discussion of C8-BTBT-Based Devices in LiteratureIn the literature, the blending of C8-BTBT and PS led to improvements in the effective mobility of organic field-effect Organic field-effect transistors based on aligned small molecule semiconductors have shown high charge carrier mobilities in excess of 10 cm 2 V −1 s −1 . This makes them a viable alternative to amorphous inorganic semiconductors especially if a high reproducibility can be achieved. Here, the optimization of high mobility organic field-effect transistors based on the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b] benzothiophene (C8-BTBT) via the addition of a polymer additive to the printing solution is reported. Specifically, films and devices are compared based on solutions of the neat semiconductor and the blend with polystyrene and shear-coated devices with excellent device characteristics and gate-voltage-ind...

Low‐voltage organic field‐effect transistors (OFETs) are of great interest for organic electronics applications that require low power consumption such as wearable electronics, biomedical applications, or mobile electronics. In this work, an approach leading to transistors fabricated from solution with high charge carrier mobilities operating at voltages < 1 V is presented. By blending the small‐molecule semiconductor 6,13‐bis(triisopropylsilyl‐ethynyl)pentacene (TIPS‐pentacene) with polystyrene it is possible to achieve good film coverage and uniformity as well as ultrathin semiconductor films. This reduction in thickness relative to neat films results in a high fraction of the high‐mobility polymorph of TIPS‐pentacene and excellent film morphologies with continuous highly crystalline domains. OFETs using SiO2 as the dielectric with average hole mobilities as high as 8.3 cm2 V−1 s−1 and maximum mobilities of up to 12.3 cm2 V−1 s−1 which favorably compares with the previous record for TIPS‐pentacene, especially when considering the simplicity of the approach, are demonstrated. By depositing the optimized semiconductor blends on solution‐based polymer dielectric layers of polyvinylphenol, cross‐linked with 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, a record‐high mobility of 4.2 cm2 V−1 s−1 for solution‐processed, ultralow‐voltage OFET devices (operating at <1 V) is obtained.

No abstract

With the prospect of realizing innovative technologies by large‐area fabrication at low cost and high throughput, printing and coating technologies are being intensively researched for the deposition of functional films. One promising coating technology is solution shearing, which has been studied as a deposition technique for organic semiconductors but not to a greater extent for dielectric layers. Therefore, the deposition by solution shearing of high‐quality poly(4‐vinylphenol) dielectrics is investigated, and the utility of these films as ultra‐smooth dielectric substrates for transistors is demonstrated. By comparing these films to those prepared by spin‐coating, it is possible to highlight the advantages of the technique. Specifically, thinner films with thicknesses as low as 11.4 nm but still low leakage and almost identical surface properties can be achieved. Thus, dielectric films with a very high capacitance of 280 nF cm‐2 are realized in a single coating step. Probing these films within organic transistors shows that they can facilitate operation at voltages as low as ‐1 V. Finally, it is shown how the use of a polymer‐small‐molecule–semiconductor blend can pave the way toward high‐performance, ultra‐low‐voltage devices from solution.

No abstract

Fully mass printed, flexible and truly polymeric organic field effect transistors consisting of a three layer dielectric made of CYTOP (low-k), PVA (intermediate) and P(VDFTrFE-CTFE)(high-k) are introduced. Gravure-, flexo-and screen printing were selected as highly productive manufacturing technologies. These OFETs work at strongly reduced voltages and show high field effect mobility (m 5 0.2 cm 2 /Vs) and remarkable good bias stress stability at very high current density (50 mA/mm). Fully printed OFETs are used for the realization of ring oscillators working in the kHz regime at reduced supply voltage (10 V). In combination with printed fully polymeric piezoelectric loudspeakers, this work shows for the first time fully printed flexible audio systems.

No abstract

No abstract