Inkjet-Printed Oxide Thin-Film Transistors Based on Nanopore-Free Aqueous-Processed Dielectric for Active-Matrix Quantum-Dot Light-Emitting Diode Displays

Ionic Liquid-Assisted Ink for Inkjet-Printed Indium Tin Oxide Transparent and Conductive Thin Films

Drop-on-demand inkjet printing is used to deposit indium tin oxide (ITO) transparent and conductive thin films. ITO printable ink is prepared by dissolving indium hydroxide and tin (IV) chloride into ethanol with the assistance of acetic acid/tert-butylamine ionic liquid. Ionic liquid-assisted ITO ink exhibits a complete wetting behavior on the glass substrate and a tunable viscosity, which makes it particularly suitable for the inkjet printing fabrication of ITO thin films. After annealing at 500 °C in forming gas, ITO thin films with a sheet resistance of 99 Ω/□, a resistivity of 2.28 × 10^-3 Ω·cm, and a transmittance of 95.2% in the range of 400-1000 nm can be obtained. The effects of annealing temperature on the resistivity, mobility, carrier concentration, transmittance, and optical band gap are investigated systematically. Compared with commercial ITO thin films made by conventional vacuum-based deposition approaches, these printable ITO thin films have a higher material utilization.

Progress in the Development of Active-Matrix Quantum-Dot Light-Emitting Diodes Driven by Non-Si Thin-Film Transistors

This paper aims to discuss the key accomplishments and further prospects of active-matrix (AM) quantum-dot (QD) light-emitting diodes (QLEDs) display. We present an overview and state-of-the-art of QLEDs as a frontplane and non-Si-based thin-film transistors (TFTs) as a backplane to meet the requirements for the next-generation displays, such as flexibility, transparency, low power consumption, fast response, high efficiency, and operational reliability. After a brief introduction, we first review the research on non-Si-based TFTs using metal oxides, transition metal dichalcogenides, and semiconducting carbon nanotubes as the driving unit of display devices. Next, QLED technologies are analyzed in terms of the device structure, device engineering, and QD patterning technique to realize high-performance, full-color AM-QLEDs. Lastly, recent research on the monolithic integration of TFT-QLED is examined, which proposes a new perspective on the integrated device. We anticipate that this review will help the readership understand the fundamentals, current state, and issues on TFTs and QLEDs for future AM-QLED displays.

Quantum Dot Arrays Fabricated Using In Situ Photopolymerization of a Reactive Mesogen and Dielectrophoresis

Dielectrophoresis (DEP) is an excellent tool for manipulating small particles within a liquid or gas medium. However, when the size of the particles is too small, such as with quantum dots (QDs), it is difficult to manipulate the particles using DEP because the dielectrophoretic force (F_DEP) depends on the volume of the particles and is therefore too weak to achieve particle migration. Herein, we demonstrate a novel method for controlling nanoscale QD particles using DEP by introducing photopolymerized reactive mesogen (RM) bead vehicles. The size of an RM bead is well-controlled by the RM concentration in the medium, and when the size is approximately 0.2 μm or larger, the RM beads can be arbitrarily manipulated using DEP under moderate electric fields. Interestingly, during photopolymerization, QD particles are easily absorbed by polymerized RM beads and most of the QDs are embedded within the RM beads. Hence, we can fabricate periodic QD arrays by manipulating the RM beads containing such dots. In addition, we can fabricate multicolor QD arrays by repeating the processes using different QD particles. The shape of a DEP-assisted QD-RM network pattern can be precisely predicted by calculating the gradient of the square of the electric field (∇E²) and the corresponding F_DEP. This new technology may be useful for the fabrication of optical devices, displays, photonic crystal devices, and bioapplications.

Flexible translucent chitosan-glycerin/QD nanocomposite glue for anti-counterfeiting films with strong adhesion and stability

With the rapid development of commodity circulation, more attention has been paid to the anticounterfeiting technology of commodities, including stability, universality and ease of distinguishing. The authors report the use of gelatin-chitosan-glycerin/QD nanocomposite-functionalized glue for luminescent anti-counterfeiting labels. As the blend and plasticizer, the addition of chitosan and glycerin effectively improved the flexibility and formability of the gelatin-chitosan-glycerin/QD composite films, which show excellent mechanical properties, including high transparency, luminescence and flexibility, and they are easy to prepare on a large scale, providing certain reference values for new anticounterfeiting technology applying a variety of morphologies.

Inkjet-Printed Top-Gate Thin-Film Transistors Based on InGaSnO Semiconductor Layer with Improved Etching Resistance

Inkjet-printed top-gate metal oxide (MO) thin-film transistors (TFTs) with InGaSnO semiconductor layer and carbon-free aqueous gate dielectric ink are demonstrated. It is found that the InGaO semiconductor layer without Sn doping is seriously damaged after printing aqueous gate dielectric ink onto it. By doping Sn into InGaO, the acid resistance is enhanced. As a result, the printed InGaSnO semiconductor layer is almost not affected during printing the following gate dielectric layer. The TFTs based on the InGaSnO semiconductor layer exhibit higher mobility, less hysteresis, and better stability compared to those based on InGaO semiconductor layer. To the best of our knowledge, it is for the first time to investigate the interface chemical corrosivity of inkjet-printed MO-TFTs. It paves a way to overcome the solvent etching problems for the printed TFTs.