ABSTRACT
Electrohydrodynamic (EHD) jet printing is known as a versatile method to print a wide viscosity range of materials that are impossible to print by conventional inkjet printing. Hence, with the understanding of the benefits of EHD jet printing, solution-based MoS2 and a high-viscosity Ag paste were EHD jet-printed for electronic applications in this work. In particular, printed MoS2 TFTs with a patterned Ag source and drain were successfully fabricated with low-k silica (SiO2) and high-k alumina (Al2O3) gate dielectrics, respectively. Eventually, the devices based on Al2O3 exhibited much better electrical properties compared to the ones based on SiO2. Interestingly, an improvement of around one order of magnitude in hysteresis was achieved for devices after changing the gate insulator from SiO2 to Al2O3. In effect, the results of this work for the printed MoS2 and the printed Ag source and drains for TFTs demonstrate a new approach for jet printing in the fabrication of electronic devices.
ABSTRACT
Transition metal dichalcogenide-based thin-film transistors (TFTs) have drawn intense research attention, but they suffer from high cost of materials and complex methods. Directly printed transistors have been in the limelight due to low cost and an environmentally friendly technique. An electrohydrodynamic (EHD) jet printing technique was employed to pattern both MoS2 active layer and Ag source and drain (S/D) electrodes. Printed MoS2 lines were patterned on a silicon wafer using a precursor solution and simple annealing, and the patterns were transferred on other SiO2 substrates for TFT fabrication. On top of the patterned MoS2, Ag paste was also patterned for S/D electrodes using EHD jet printing. The printed TFTs had a high on-off current ratio exceeding 105, low subthreshold slope, and better hysteresis behavior after transferring MoS2 patterns. This result could be important for practical TFT applications and could be extended to other 2D materials.
ABSTRACT
Solution synthesis of MoS2precursor followed by direct printing could be an effective way to make printed electronic devices. A linear MoS2pattern was obtained by an electrohydrodynamic (EHD)-jet printer with a sol-gel system without chemical vapor deposition. The morphology of the MoS2after a transfer process was maintained without wrinkles or cracking, resulting in a smooth surface compared with that of spin-coated films. EHD-jet printed MoS2was transferred onto high-kdielectric Al2O3and used as a semiconductor layer in thin film transistor (TFT) devices. The printed MoS2TFT has relatively good electrical characteristics, such as a linear field effect mobility, current ratio, and low subthreshold swing of 47.64 ± 2.99 cm2V-1s-1, 7.39 ± 0.12 × 106, and 0.7 ± 0.05 V decade-1, respectively. This technique may have promise for future applications.
ABSTRACT
The electrohydrodynamic (EHD) jet spraying process is a good method for making quantum dot (QD) layers in light-emitting diodes (LEDs). However, controlling the morphology and large-scale fabrication of the QD layers are critical for realizing all-solution-processed QD-LEDs with high performance. Three spraying techniques were used with the EHD jet spraying technique: a big circular film method, a spiral-line method, and a straight-line method. These techniques were used to obtain QD films with good uniformity. The straight-line spray showed the most promise to obtain a uniform QD layer with large area, and QD-LEDs made with this method showed better performance with a low turn-on voltage of 3.0 V, a luminance of 7801 cd/m2, and a maximum current efficiency of 2.93 cd/A.
ABSTRACT
Electrohydrodynamic (EHD) jet printing has a variety of benefits compared to conventional inkjet techniques, such as high resolution and the ability to work with high-viscosity pastes. In this work, Ag nanoparticles with 4000 cPs were chosen because they are printable on various substrates for electronic devices. The effects of additive on the high-viscosity Ag paste formulation were investigated, and pattern lines narrower than 100 µm were achieved by EHD-jet printing with an average sheet resistance of 0.027 Ω â¡-1. Furthermore, solution-processed oxide TFTs were fabricated with EHD jet-printed Ag electrodes for the first time. The electrical properties obtained were a current ratio of 1.5 × 106, a mobility of approximately 1 cm2 V-1 s-1, a threshold voltage of 21.5 V, and a subthreshold slope of 3.05 V dec-1.
