•Fast operation of printed organic inverter circuits is demonstrated.•Optimization of semiconducting solution improves both mobility and on/off ratio.•Modifications SAM for printed source–drain electrodes improves mobility.•Printed organic TFTs with L < 10 μm exhibit high mobility of 1.2 cm2/V s.•Diode-load inverters with short channels operate at 8 kHz at 20 V.We have demonstrated fast operation of printed organic inverter circuits. We employ a soluble organic semiconducting material which has high field-effect mobility and ink-jet printed source/drain electrodes with short channel length. Appropriate concentration of the semiconducting solution and modification layer of source/drain electrodes improve both mobility and on/off ratio. The fabricated transistors with a short channel length (4 μm) exhibit excellent mobility (1.2 cm2/V s), high on/off ratio (>105) and operational stability. The diode-load inverter with a narrow channel and low parasitic capacitance operate at 8 kHz at 20 V. These results will lead to significant progress in applications of printed organic circuits.

We report on the cross-sectional profile control of printed electrodes fabricated from silver nanoparticle inks with water-based solvents by inkjet printing. Systematically varying the ambient conditions and time for the drying process corresponded to changes in electrode shape. In general, lower humidity levels resulted in concave electrode profiles due to the coffee-ring effect, while higher humidity levels resulted in convex profiles. Printed capacitors with trapezoidal-shaped lower electrodes showed much better electrical breakdown strength than those with concave-shaped lower electrodes. Solution-processed organic thin-film transistors with trapezoidal gate electrodes operated reproducibly and exhibited good electrical characteristics with very low gate-leakage currents. The methods can be utilized in the fabrication of printed electronic devices with stacked layers, such as thin-film capacitors and transistors.Keywords: humidity; inkjet printing; organic thin-film transistors; printed electronics; profile control; silver nanoparticle ink;

•We fabricated organic TFTs and pseudo-CMOS inverter using full solution-processing.•Patterning conditions for the silver nanoparticle inks are optimized.•NAND and NOR circuits based on the pseudo-CMOS circuits that are demonstrated.•Fabricated circuits exhibited good characteristics at a low supply voltage.•Low temperature processing below 150 °C.We have demonstrated fully solution-processed inverter, NAND and NOR circuits using pseudo-CMOS logic and p-type organic TFT devices with printed electrodes that were fabricated using ink-jet printed silver nanoparticle inks at low temperatures. In order to optimize the gate electrode profiles, we thoroughly assessed the surface wettability of the silver nanoparticle inks. The pseudo-CMOS inverter circuit exhibited exceptional switching characteristics with a high signal gain of 34 at a supply voltage of 20 V. The NAND and NOR circuits also exhibited excellent logic characteristics, whereby the switching voltage was approximately VDD/2 with a high noise margin and short delay time of 12.5 ms.

Organic integrated circuits based on organic thin-film transistor (TFT) devices are fabricated with solution-based electrodes by using dense inks of silver nanoparticles, which can be sintered at room-temperature. The TFT devices fabricated at a sintering temperature of 30 °C exhibit good electrical characteristics. There is a strong relation between the sintering temperature of silver nanoparticle inks and transistor characteristics. A work function of silver electrodes can be controlled by changing the sintering temperature of silver nanoparticle inks, thereby threshold voltage of fabricated TFT devices are shifted accordingly. Fabricated pseudo-CMOS inverter circuits are successfully operated at low voltage with small hysteresis, and large gains are obtained. These results suggest that printed organic TFT devices fabricated with a low-temperature process enable large-area and low-cost integrated circuits by using these techniques in future applications.Graphical abstractHighlights► Organic TFTs with room-temperature sintered printed electrodes are fabricated. ► A Work function of silver electrodes can be controlled. ► Threshold voltages are shifted by changing the sintering temperature of electrodes. ► Inverter circuits are operated with no hysteresis and large gain are obtained.

We have fabricated electronically stable organic thin-film transistor (TFT) devices that are fully solution-processed and adopt printed electrodes using silver nanoparticles dispersed in organic solvents, whose sintering temperatures are 100 °C or less. The bottom-contact organic TFT devices showed good electrical characteristics, and exhibited threshold voltage shifts less than 2.0 V after applying a DC bias voltage stress for 104 s, which is attributed to relatively low contact resistance. These results demonstrate the feasibility of producing stable organic TFTs that are fully solution-processed at relatively low temperatures, for use in large-area flexible electronics applications.Graphical abstractHighlights► We fabricate organic TFTs using full solution-processing. ► The fabrication process of printed silver electrodes is less than 100 °C. ► Fabricated TFTs show good electrical characteristics. ► The threshold voltage does not change under the DC bias voltages.