Light emitting diodes (LEDs) based on a metal-oxide-semiconductor-like (MOS-like) structure with Si nanocrystals (nc-Si) embedded in SiO<sub>2</sub> have been fabricated with low-energy ion implantation. Under a negative gate voltage as low as ~-5 V, both visible and infrared (IR) electroluminescence (EL) have been observed at room temperature. The EL spectra
are found to consist of four Gaussian-shaped luminescence bands with their peak wavelengths at ~460, ~600, ~740, and
~1260 nm, in which the ~600-nm band dominants the spectra. The EL properties have been investigated together with
the current transport properties of the Si<sup>+</sup>-implanted SiO<sub>2</sub> films. A systematic study has been carried out on the effect of
the Si ion implantation dose and the energy on both the current transport and EL properties. The mechanisms of the
origin of the four different EL bands have been proposed and discussed.
We report the results of an effort to understand the effect of surface electronic structure of indium tin oxide (ITO) on luminance efficiency of organic light-emitting devices (OLED)s. Nitric oxide (NO) plasma was used to modify the ITO. NO plasma induced an increase in the sheet resistance of ITO. The surface electronic structure of ITO was studied using X-ray photoelectron spectroscopy. An approximately 4-nm thick low conductivity layer with a production of N-O type species was formed near the ITO surface region. It is demonstrated that the barrier for hole-injection from an ITO anode to a hole transporting layer can be engineered by NO plasma treatment. The increase in luminance efficiency of the OLEDs reflects an improved current balance in the device.
Displays based on organic electroluminescent (EL) materials have entered the marketplace already and demonstrated remarkable contrast, high brightness and crisp colors. However, one of the key advantages of this new technology has not been commercially exploited yet: Fabrication of a display that is still fully functional even when it is bent or flexed. This is possible since organic EL devices comprising only thin, amorphous solid state films and optical properties have no critical dependence on the film thickness. In this paper we address the important elements that are required to produce a flexible organic EL display. Most crucial is the selection of a flexible substrate. Here we present results obtained with ultra-thin inorganic glass materials as well as polymeric foils. For the glass substrates we determined the ultimate mechanical properties for different device configurations. In the case of polymeric substrates permeation of water and oxygen molecules through the substrate is the governing factor. We compare the performance of different barrier systems. In summary we demonstrate that OLED devices with certain flexibility can be reliably built on ultra-thin glass substrates. For polymeric substrates a lot of progress has been achieved in terms of the required barrier properties and other necessary ingredients and this might result later into a commercial organic EL product.