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In this work, a water/alcohol-soluble conjugated polymer poly [(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9–dihexylfluorene)] (PFNC6) is synthesized and the photophysical properties are investigated. Subsequently, it is tested as electron injection layer in a blue emitting OLED with PFO. The maximum current efficiency (CE) and external quantum efficiency (EQE) of the device increased by 3 times to 0.75 cd/A and 0.66%. Further enhancement in the OLED performance is obtained when a bilayer electron injection consisting of PFNC6 and LiF are used where the maximum CE is 2.16 cd/A and the maximum EQE is 1.55%. Measurement with electron-only-devices confirmed that the electron mobility is increased for the device with PFNC6 as compared to the control device. Furthermore, higher Vbi is obtained in photovoltaic measurement when PFNC6 is used. As a result, the electron injection barrier is reduced and electron injection is more efficient.

The plasma characteristics of 355 nm and 532 nm laser ablation of Al-doped ZnO (AZO) target were studied by optical emission spectroscopy and ion probe measurements. Zn emission lines were measured detected at above 0.9 J/cm 2 for 355 nm laser and 0.6 J/cm 2 532 nm laser respectively, while Al species were detected only above 2 J/cm 2 . The kinetic energy of the ions was slightly higher for 532 nm ablation as compared to 355 nm ablation. In addition, the ablation of 532 nm laser was affected by the large laser penetration depth. When deposited at 2 and 4 J/cm 2 , AZO films with energy band gap of 3.45–3.6 eV were obtained. Nanostructured AZO films were obtained by 355 nm laser ablation but nano and micro-particulates were formed in 532 nm laser ablation. The large micron-sized particulates were Al-rich thus affecting not only the morphology but also the stoichiometry of the films. It is thus concluded that despite a lower ablation and growth rate, 355 nm generated Zn, O and also Al species at lower threshold fluence that can lead to high quality AZO films at room temperature.

Background gases (O2, He or Ar) with the pressure from ~ 10−3 Pa to 133.3 Pa are used in 355 nm laser deposition of Al-doped ZnO at room temperature. The effects of these gases and pressure on plasma formation are studied by optical emission spectroscopy (OES) and time of flight (TOF) measurement. The OES results show that the emission intensity of the species in O2 and Ar decrease slightly and then increase exponentially above ~ 5 Pa. The emission intensity in Ar is the highest, followed by emission in O2 whilst the emission in He is low and weakly depend on background gas pressure. TOF measurements indicate that the ion velocity decrease with increasing O2 and Ar pressure at about 5–10 Pa. The ion velocity is highest in He while the ion velocities in O2 and Ar are similar. Thin-film samples deposited in different gas at 2.6 Pa are amorphous, but those deposited at 133.3 Pa are crystalline and exhibit different morphologies and optical properties depending on type of gas. Samples deposited in O2 are highly transparent but those deposited in He and Ar contain nano and micron-sized structures with

In this work, we investigated on the growth of Cu 2 ZnSnS 4 films by using pulsed Nd:YAG laser (355 nm) ablation of a quaternary Cu 2 ZnSnS 4 target. Depositions were performed at laser fluence from 0.5 to 4 J cm −2 . The films were grown at substrate temperature from 27 °C to 300 °C onto glass and silicon substrates. The dependence of the film morphology, composition, and optical properties are studied and discussed with respect to laser fluence and substrate temperature. Composition analysis from energy dispersive X-ray spectral results show that CZTS films with composition near stoichiometric were obtained at an optimized fluence at 2 J cm −2 by 355 nm laser where the absorption coefficient is >10 4 cm −1 , and optical band gap from a Tauc plot was ∼1.9 eV. At high fluence, Cu and Sn rich droplets were detected which affect the overall quality of the films. The presence of the droplets was associated to the high degree of preferential and subsurface melting on the target during high fluence laser ablation. Crystallinity and optical band gap (1.5 eV) were improved when deposition was performed at substrate temperature of 100 °C.

The generation of a homogeneous plasma plume is necessary for the pulsed laser deposition of thin films. In this work, we investigate the effects of nanosecond-duration laser pulses to ablate polycrystalline Si targets in vacuum ( −4 Pa) at room temperature. The laser wavelength covers the range from ultra-violet to infrared by using a KrF (248 nm, 25 ns) and a Nd:YAG (1064 nm, 532 nm, 355 nm, 5 ns) laser. The films were deposited at laser fluences from 1 to 6 J/cm 2 and characterized by atomic force microscopy and spectroscopic ellipsometry. Time-integrated optical emission spectra were obtained for excited neutrals and ionized Si species in the plasma produced between 0.5 and 11 J/cm 2 . The relation between the ionized species and film properties were discussed.

In this work, we investigated the laser ablation and deposition of Si and Ge at room temperature in vacuum by employing nanosecond lasers of 248 nm, 355 nm, 532 nm and 1064 nm. Time-integrated optical emission spectra were obtained for neutrals and ionized Ge and Si species in the plasma at laser fluences from 0.5 to 11 J/cm2. The deposited films were characterized by using Raman spectroscopy, scanning electron microscopy and atomic force microscopy. Amorphous Si and Ge films, micron-sized crystalline droplets and nano-sized particles were deposited. The results suggested that ionized species in the plasma promote the process of subsurface implantation for both Si and Ge films while large droplets were produced from the superheated and melted layer of the target. The dependence of the properties of the materials on laser wavelength and fluence were discussed.

This paper presents the results, analysis and discussions of parametric studies of diamond-like carbon (DLC) thin films by pulsed Nd:YAG laser deposition. Effects on the DLC properties and growth rate were investigated by varying the deposition parameters, namely the laser wavelength and fluence, substrate and temperature. For characterization, visible Raman spectroscopy, current-voltage measurement, optical interferometry, and optical absorption technique were employed. Comparisons were made with previous work by other workers who had also employed pulsed Nd:YAG lasers. The results also supported the subplantation mechanism for DLC formation.

Nickel (Ni) thin films were deposited on glass substrates in high vacuum and at room temperature with third-harmonic or 355-nm output from a nanosecond Nd:YAG laser. At low laser fluence of 1 J/cm2, the deposition rate was about 0.0016 nm/shot which increased linearly until 4 J/cm2. Above 4 J/cm2, the onset of phase explosion in the ablation abruptly increased the optical emission intensity from laser-produced Ni plume as well as thin-film deposition rate by about 6×. The phase explosion also shifted the size distribution and number density of Ni droplets on its thin-film surface. On the other hand, the surface structures of the ablated Ni targets were compared between the scan-mode and the fixed-mode ablations, which may suggest that droplets observed on the thin-film surface were caused by direct laser-induced splashing of molten Ni rather than vapour-to-cluster condensation during the plume propagation.

A thorough study of MSnO 3 (M=Ca, Sr and Ba) compounds with respect to their synthesis, processing and microstructural characterization has been made. In order to establish a standard methodology with identical and beneficial microstructure and reproducible electrical characteristics, a novel preparative method called self-heat-sustained (SHS) reaction technique was employed. Evolution of microstructure which is intimately related to the envisaged properties in the ceramics, was closely and systematically followed in terms of wide temperature-soak time ( T-t ) profiles. The results showed that while a well-densified microstructure with small grain size (∼1 μm) and near zero porosity could be obtained by selecting a sintering schedule of 1350°C/ x h (48 h x ⩽ 60 h) for CaSnO 3 samples, very well sintered samples with relatively larger grains (3–5 μm) and minimal porosity could also be obtained by sintering at 1600°C for 2 h. Well-densified microstructure with small grain size and zero or near zero porosity could be obtained by a sintering schedule of 1350°C/ x h (12 h x ⩽ 24 h) in SrSnO 3 samples. Sintering of BaSnO 3 proved to be the most difficult. The BaSnO 3 samples could only be densified to the desired level by soaking the powder compacts for 2 h at 1600°C. The “sugar cube” features were replaced by the spherical grains (average size 1–2 μm).

Nanowires of indium tin oxide (ITO) were grown on catalyst-free amorphous glass substrates at relatively low temperature of 250 °C in argon and helium ambient by the Nd:YAG pulsed laser deposition technique. All the ITO samples showed crystalline structure due to substrate heating and the (400) X-ray diffraction peak became relatively stronger as the pressure was increased. The surface morphology was also changed from compact, polycrystalline thin-film layers to a dendritic layer consisting of nanowires for some limited pressure ranges. The transition from the normal thin-film structure to nanowires was likely due to the vapor–liquid–solid mechanism but under catalyst-free condition. These nanowires tended to grow perpendicularly on the glass substrate, as observed with the transmission electron microscopy (TEM), which also confirmed that these nanowires were crystalline.