AVS 49th International Symposium
    Organic Films and Devices Wednesday Sessions
       Session OF+EL+SS+SC-WeM

Paper OF+EL+SS+SC-WeM6
DLC Thin Film as Electron Injection Layer in Organic LEDs

Wednesday, November 6, 2002, 10:00 am, Room C-102

Session: Metal-Organic Interfaces
Presenter: M. Cremona, Pontificia Universidade Catolica do Rio de Janeiro, Brazil
Authors: M. Cremona, Pontificia Universidade Catolica do Rio de Janeiro, Brazil
R. Reyes, Universidad Nacional de Ingeniería, Perú
C.A. Achete, Universidade Federal do Rio de Janeiro, Brazil
P.I. Guimarães, Universidade Federal do Rio de Janeiro, Brazil
S.S. Camargo, Jr., Universidade Federal do Rio de Janeiro, Brazil
Correspondent: Click to Email
Recently, there has been an increased interest in organic light emitting diodes (OLEDs) due of their potential applications to color flat panel displays and in new optoelectronic components. These devices are assembled using three organic molecular materials: an electron injection layer, the emitting one and finally the hole injection layer. However, in most cases the electron injection is more difficult to achieve than hole injection. In this work two different diamond like carbon (DLC) thin films cathode were used to decrease the electron injection barrier. The first kind were nitrogen-doped amorphous hydrogenated hard carbon films deposited by rf glow discharge from methane-nitrogen mixtures onto the TPD/Alq@sub 3@ layer structure thermally deposited. DLC films were obtained for different N@sub 2@ partial pressures (bias voltage V@sub b@=–370 V and total pressure P=8 Pa). Next, amorphous carbon nitride thin films (a-CN@sub x@) have been deposited using a rf diode sputtering system onto the same organic structure. In this case the DLC films were deposited in reactive nitrogen-argon atmospheres. The partial pressure of nitrogen ranged from 0% to 100% at two different deposition pressures (P = 2 Pa and P = 8 Pa). In both cases a thick (150 nm) aluminum electrode were deposited onto the whole structure. The deposition process for the organic compounds is performed in high vacuum environment (6x10@super -6@ Torr) on glass substrates coated with an hole injecting ITO transparent layer. A preliminary investigation was conducted on the properties of the OLED device with the two DLC intermediate layers. The relationship between the properties of the DLC deposited films on the electroluminescent characteristics of the different devices are investigated. The refractive index of the DLC film deposited, their conductivity and optical absorption, the OLED I-V curves, a preliminary photoluminescent and electroluminescent OLED results are presented and discussed.