Flexible Indium Tin Oxide Film Research Articles

Role of plasma parameters on the characteristics properties of flexible transparent ITO films deposited by 3D facing and planar facing magnetron sources

A rectangular closed and hollow three-dimensionally confined large area magnetron source (3-DCLAMS) and a conventional moderate area facing target magnetron source (FTMS) have been used to study the plasma characteristics using different diagnostics at different working pressures. Flexible indium tin oxide (ITO) films deposited at similar operating conditions using these sources were characterized by numerous standard analyses to study their film properties. The 3-DCLAMS with high discharge current at a low-discharge voltage is capable of generating high plasma density, which assists a high ion flux and energy density on the substrate that is necessary for the high growth rate deposition of highly conductive crystalline ITO films with smooth surface morphology. Utilizing suitable plasma characteristics, highly conductive and transparent ITO films of 30 nm with the minimum resistivity ρ ∼ 4.1 × 10−4 Ω cm and ∼9.3 × 10−4 Ω cm and average transmittance T ∼ 84% and 82%, respectively, were deposited in the 3-DCLAMS and the FTMS system. The presented result shows that the 3-DCLAMS system could be useful for making high-quality, flexible ITO films at a very high deposition rate of ∼250 nm/min.

A Flexible Tactile Sensor with Irregular Planar Shape Based on Uniform Electric Field.

Tactility is an essential perception for intelligent equipment to acquire external information. It can improve safety and performance during human-machine interactions. Based on the uniqueness theorem of the electrostatic field, a novel flexible film tactile sensor that can detect contact position and be made into any plane shape is proposed in this paper. The tactile sensor included an indium tin oxide (ITO) film, which was uniformly coated on the polyethylene terephthalate (PET) substrate. A specially designed strong conductive line was arranged along the edge of the flexible ITO film, which has weak conductivity. A bias excitation was applied to both ends of the strong conductive line. Through the control of the shape of the strong conductive line, a uniform electric field can be constructed in the whole weak conductive plane. According to the linear relationship between position and potential in the uniform electric field, the coordinate of the contact position can be determined by obtaining the potential of the contact point in the weak conducting plane. The sensor uses a three-layer structure, including an upper conductive layer, an intermediate isolation layer, and a lower conductive layer. A tactile sensor sample was fabricated. The experiment results showed that the principle of the tactile sensor used for the contact position detection is feasible and has certain precision of position detection. The sensor has good flexibility, and can be made into any plane shape, and has only four wires. It is capable of covering large areas of robot arms, and provides safety solutions for most robots.

Cohesively Enhanced Conductivity and Adhesion of Flexible Silver Nanowire Networks by Biocompatible Polymer Sol–Gel Transition

Silver nanowire (AgNW) networks are a promising candidate to replace indium tin oxide (ITO) as transparent conductors. In this paper, a novel transparent composite conductor composed of AgNW/biocompatible alginate gel on a flexible polyethylene terephthalate (PET) substrate, with synchronously enhanced adhesion and reduced resistivity, is prepared without high‐temperature annealing. The sheet resistance of the flexible AgNW/PET film reduces from 300 to 50.3 Ohm sq−1 at transmittance of 94%. The optical and electrical performance is superior to that obtained from the flexible ITO film on PET. Meanwhile, the sheet resistance does not show great change after tape test, suggesting a good adhesion of AgNW to the polymer substrate. Moreover, the AgNW composite film shows a good stability to resist long‐term storage, solvent damage, and ultrasonication. Finally, polymer solar cells employing the composite AgNW film as the electrode are realized, displaying an efficiency of 2.44%.

Enhanced electrical stability of flexible indium tin oxide films prepared on stripe SiO 2 buffer layer-coated polymer substrates by magnetron sputtering

The electrical stability of flexible indium tin oxide (ITO) films fabricated on stripe SiO 2 buffer layer-coated polyethylene terephthalate (PET) substrates by magnetron sputtering was investigated by the bending test. The ITO thin films with stripe SiO 2 buffer layer under bending have better electrical stability than those with flat SiO 2 buffer layer and without buffer layer. Especially in inward bending text, the ITO thin films with stripe SiO 2 buffer layer only have a slight resistance change when the bending radius r is not less than 8 mm, while the resistances of the films with flat SiO 2 buffer layer and without buffer layer increase significantly at r = 16 mm with decreasing bending radius. This improvement of electrical stability in bending test is due to the small mismatch factor α in ITO–SiO 2, the enhanced interface adhesion and the balance of residual stress. These results indicate that the stripe SiO 2 buffer layer is suited to enhance the electrical stability of flexible ITO film under bending.

An alternative bend-testing technique for a flexible indium tin oxide film

The two-dimensional refractive index distribution of a flexible indium tin oxide film deposited on a PET layer is measured before/after the bend-testing with an alternative technique based on Fresnel equations and the heterodyne interferometry. Their standard deviations are derived and they vary more obviously than the resistance variations measured in the conventional method. Hence the standard deviation of the refractive index can be used as the indicator to justify the durability of a flexible indium tin oxide film. The validity is demonstrated.

Effects of SiO2 and TiO2 on resistance stabilities of flexible indium-tin-oxide films prepared by ion assisted deposition

Inorganic buffer layers such as SiO2 or TiO2 and transparent conductive indium-tin-oxide (ITO) films were prepared on polyethylene terephthalate (PET) substrates by ion assisted deposition (IAD) at room temperature, and the effects of SiO2 and TiO2 on the bending resistance performance of flexible ITO films were investigated. The results show that ITO films with SiO2 or TiO2 buffer layer have better resistance stabilities compared to ones without the buffer layer when the ITO films are inwards bent at a bending radius more than 1.2 cm and when the ITO films are outwards bent at a bending radius from 0.8 cm to 1.2 cm. ITO films with SiO2 buffer layer have better resistance stabilities compared to ones with TiO2 buffer layer after the ITO films are bent several hundreds of cycles at the same bending radius, for the adhesion of SiO2 is stronger than that of TiO2. The compressive stress resulted from inward bending leads to the formation of more defects in the ITO films compared with the tensile stress arising from outward bending. SiO2 and TiO2 buffer layers can effectively improve the crystallinity of ITO films in (400), (440) directions.

The characteristics of indium tin oxide films prepared on various buffer layer-coated polymer substrates

The optoelectronic and mechanical properties of flexible indium tin oxide (ITO) films are critical to the development of flexible optoelectronic devices. To improve the characteristics of the flexible films, the effects of inorganic buffer layers on the optoelectronic and mechanical characteristics of flexible ITO films prepared by ion-beam assisted deposition at room temperature were investigated. The results show that four inorganic buffer materials: SiO 2, Ta 2O 5, Al 2O 3 and TiO 2, have different effects on the optical transmission, sheet resistance and mechanical properties of ITO films. Ta 2O 5 buffer layer induces the highest optical transmission. SiO 2 buffer layer leads to the lowest sheet resistance. TiO 2 buffer layer reveals the most superior electrical stability against bending, which is attributed to the low thermal stress in ITO film.

Smooth, transparent, conducting and flexible SWCNT films by filtration–wet transfer processes

Single-walled carbon nanotube (SWCNT) films were prepared using a novel filtration–wet transfer process. The sheet resistance, optical transmittance, optical conductivity, dc conductivity and flexibility of the fabricated films were measured and compared with those of commercialized flexible indium tin oxide films. The shorter fabrication time, use of only water as the transferring medium, surface roughness of <3 nm, film thickness of <12 nm and maintenance of its electrical properties after film deformation make it an attractive material for flexible plastic electronics.

A Bilayer Organic Light-Emitting Diode Using Flexible ITO Anode

Flexible organic light-emitting diodes (OLEDs) with ITO (Indium-Tin-Oxide)/TPD (N, N′-diphenyl-N, N′-(3-methylphenyl)-1, 1′-biphenyl-4, 4′-diamine)/Alq3(tris (8-hydroxyquinoline) aluminum)/Al configuration prepared on polyester substrates (polyester devices) were fabricated. The light-emitting and current–voltage (I–V) characteristics of the devices were investigated. Compared to those with glass substrates (glass devices) fabricated under the same conditions, the threshold voltage of the polyester devices was almost the same. The current and luminescent characteristics showed an obvious improvement when the thickness of the organic layers is increased. Distributive bursting emerged when the applied voltage increased over a certain value. The reasons causing the failure of the devices were analyzed. It was found that weaker adhesion and larger surface fluctuation of the flexible ITO films were leading factors affecting the stability of the polyester devices, which was different from that of glass devices.