Thian-Khok Yong

Low-temperature synthesis of indium tin oxide nanowires as the transparent electrodes for organic light emitting devices

Low-temperature growth of indium tin oxide (ITO) nanowires (NWs) was obtained on catalyst-free amorphous glass substrates at 250 °C by Nd:YAG pulsed-laser deposition. These ITO NWs have branching morphology as grown in Ar ambient. As suggested by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), our ITO NWs have the tendency to grow vertically outward from the substrate surface, with the (400) plane parallel to the longitudinal axis of the nanowires. These NWs are low in electrical resistivity (1.6×10⁻⁴ Ω cm) and high in visible transmittance (~90–96%), and were tested as the electrode for organic light emitting devices (OLEDs). An enhanced current density of ~30 mA cm⁻² was detected at bias voltages of ~19–21 V with uniform and bright emission. We found that the Hall mobility of these NWs is 2.2–2.7 times higher than that of ITO film, which can be explained by the reduction of Coulomb scattering loss. These results suggested that ITO nanowires are promising for applications in optoelectronic devices including OLED, touch screen displays, and photovoltaic solar cells.

Analytical band Monte Carlo analysis of electron transport in silicene

An analytical band Monte Carlo (AMC) with linear energy band dispersion has been developed to study the electron transport in suspended silicene and silicene on aluminium oxide (Al2O3) substrate. We have calibrated our model against the full band Monte Carlo (FMC) results by matching the velocity-field curve. Using this model, we discover that the collective effects of charge impurity scattering and surface optical phonon scattering can degrade the electron mobility down to about 400 cm2 V−1 s−1 and thereafter it is less sensitive to the changes of charge impurity in the substrate and surface optical phonon. We also found that further reduction of mobility to ~100 cm2 V−1 s−1 as experimentally demonstrated by Tao et al (2015 Nat. Nanotechnol. 10 227) can only be explained by the renormalization of Fermi velocity due to interaction with Al2O3 substrate.

Pulsed Laser Deposition of ITO: From Films to Nanostructures

Indium-tin oxide (ITO) films have been deposited by pulsed laser deposition (PLD) to achieve low resistivity and high transmittance in visible region. Important parameters governing the growth of ITO films, which include laser wavelength, substrate temperature, and the background gas pressure, are discussed. By utilizing the energetic plasma in laser ablation of an ITO target, relatively low substrate temperature growth has been demonstrated. Room temperature deposition enables ITO films to be deposited on the polymer substrate. In addition, deposition in different background gases promotes the catalyst-free growth of nanostructured ITO films. In particular, deposition in Ar or He at optimized pressures enables the growth of highly crystalline ITO nanostructures, which include nanorods and nanowires due to the self-catalyzed growth from the plasma plume. The conditions which allow the pulsed laser deposition of ITO thin films and the growth of nanostructured ITO are reviewed and discussed.

Measurement of bending and torsional vibrational modes of optical tabletop using optical interferometry technique

This paper discusses the used of an optical interferometry technique for bending and torsional vibrational modes measurement. With this technique, the amplitude and frequency of the vibrations involved in tabletop of a home-made optical table were measured. Besides, vibrational modes involved and performance of the damping system were determined.

One‐step Double‐layer Thermal Evaporation Method for Organic Light Emitting Diodes

A new one‐step double‐layer thermal evaporation method was used to fabricate organic light emitting diodes (OLEDs) with device structure of: ITO (anode)/N,N_‐diphenyl‐N,N_‐bis(3‐methylphenyl)‐1,1_‐diphenyl‐4,4_‐diamine (TPD) /tris‐(8‐hydroxyquinoline)aluminum(3) (Alq3)/Al (cathode). These OLEDs were fabricated in cleanroom on the ITO‐coated glass with a sheet resistivity of 20Ω/sq and an optical transmittance of 90%. The I–V and brightness characteristic showed that the new method could produce better performance achieving lower turn‐on voltage (‐2V), higher peak current efficiency (+29%) and higher brightness (+36%).

Parametric Studies of Pulsed Laser Deposition of Indium Tin Oxide and Ultra-thin Diamond-like Carbon for Organic Light-emitting Devices

Device quality indium tin oxide (ITO) films are deposited on glass substrates and ultra-thin diamond-like carbon films are deposited as a buffer layer on ITO by a pulsed Nd:YAG laser at 355 nm and 532 nm wavelength. ITO films deposited at room temperature are largely amorphous although their optical transmittances in the visible range are > 90%. The resistivity of their amorphous ITO films is too high to enable an efficient organic light-emitting device (OLED), in contrast to that deposited by a KrF laser. Substrate heating at

Pulsed laser deposition of tin-doped indium oxide (ITO) on polycarbonate

200^{\circ}C

Pulsed laser deposition of indium tin oxide nanowires in argon and helium

with laser wavelength of 355 nm, the ITO film resistivity decreases by almost an order of magnitude to

Pulsed Nd:YAG laser depositions of ITO and DLC films for OLED applications

2{\times}10^{-4}\;{\Omega}\;cm

Investigation of droplet formation in pulsed Nd:YAG laser deposition of metals and silicon

while its optical transmittance is maintained at > 90%. The thermally induced crystallization of ITO has a preferred directional orientation texture which largely accounts for the lowering of film resistivity. The background gas and deposition distance, that between the ITO target and the glass substrate, influence the thin-film microstructures. The optical and electrical properties are compared to published results using other nanosecond lasers and other fluence, as well as the use of ultra fast lasers. Molecularly doped, single-layer OLEDs of ITO/(PVK+TPD+