The ultra-thin nanocomposite films based on the nano-crystal TiO2 (TiO2-nc) or multi-walled carbon nanotube (MWCNTs) were prepared and used as the buffer layers in the fabrication of the organic light-emitting diodes (OLEDs). The injection efficiency of the hole and electron was improved by inserting an ultra-thin buffer layer between the electrodes and emissive layer. | Communications in Physics, Vol. 24, No. 3S1 (2014), pp. 7-12 DOI: ENHANCED PERFORMANCE IN POLYMER LIGHT EMMITING DIODE BY USING ULTRA-THIN CONDUCTIVE FILMS AS THE BUFFER LAYER NGUYEN PHUONG HOAI NAM Faculty of Engineering Physics and Nano-Technology, University of Engineering and Technology, Vietnam National University, Hanoi E-mail: namnph@ Received 20 June 2014 Accepted for publication 20 August 2014 Abstract. The ultra-thin nanocomposite films based on the nano-crystal TiO2 (TiO2 -nc) or multi-walled carbon nanotube (MWCNTs) were prepared and used as the buffer layers in the fabrication of the organic light-emitting diodes (OLEDs). The injection efficiency of the hole and electron was improved by inserting an ultra-thin buffer layer between the electrodes and emissive layer. The turn-on voltage of the device with the buffer layers was lowered from 4 to , and the current density was increased from to mA/mm2 , in comparison with the device without such a buffer layer. These devices showed a high efficiency and good stability. Keywords: nanocomposites, conducting polymer, blended polymer, light emitting diode, CNTs. . I. INTRODUCTION Organic light-emitting diodes (OLEDs) were frequently applied to flat panel displays due to the ease of manufacturing, solid-state, faster switching speed and wider viewing angle, etc. . . Along with the developing of new technology, OLEDs have the potential to substitute the liquid crystal display (LCDs) and become the pacemaker in the display market. High performance organic light emitting diodes should have a low operating voltage, high efficiency and relatively good stability. In order to improve the efficiency of devices, various techniques are available as anode or cathode modification, annealing and optical coupling [1 - 4]. For example, cathode modification has been shown to increase the electron injection, so as to improve the electron-hole balance. As the result, the .
