Rémi Antony

Organic light-emitting diodes based on multilayer structures

Abstract We study various organic structures and explain the obtained improvements by the use of protective layer or hole transport layer in multilayer OLEDs based on Alq 3 as emitter.

Ion beam applications in molecular and macromolecular physics (optics, electronics, optoelectronics)

Abstract We present three major applications of ion beam in the area of molecular or macromolecular physics. Firstly, we report how main electrical parameters varied in function of ion types and implantation parameters; the application area is the fabrication of elementary electronic devices with electroactive polymer (PPP). Secondly, with high current density of oxygen ion beam, reactive ion beam etching allows optical device achievement in polyimide with low optical loss (0.3 dB/cm at λ=1.3 μm ). Lastly, we recently demonstrated that ion beam assisted deposition of molecular compound (Alq3: 8-tris-hydroxyquinoline-aluminium) is a promising way to obtain enhanced Organic Light Emitting Devices: Luminance as high as 600 cd/m2 is obtained with a monolayer structure.

Realization of red light-emitting diodes with a confinement layer

Abstract In order to obtain a light emission with a red color, we have realized light-emitting diodes with an electroactive polymer: the poly(3-octylthiophene) or P3OT. The internal efficiency versus applied bias characteristic is very weak ( η int =0.025%). In order to improve the electron injection, we have inserted a 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4 oxadiazole (or butyl-PBD) layer between the polymer film and the calcium cathode. With this two-layer structure, we obtain a tenfold improvement in efficiency ( η int =0.25%). Lastly, we have used another material in order to obtain a confinement layer. With an 8-tris hydroxyquinoline aluminum (or Alq3) layer, the efficiency is better (0.8%) but we observe a color light change (yellow-orange). We discuss the phenomenon.

Ion beam assisted etching of a fluorinated polyimide in order to insert it in an electro-optical system

Abstract Etching of a fluorinated polyimide (6FDA-ODA) was realized by the IBAE (Ion Beam Assisted Etching) technique which uses an inert ion beam (Ar+ for example) to carry a reactive flux (oxygen for example) towards the target.This ion beam reactive etching enables us to obtain etching rates of about 60 nm/min by maintaining a pressure of about 10−4 Torr in the irradiation chamber.

Ions size dependent characteristics of organic light-emitting diodes realized by ion beam assisted deposition

Abstract We present results about the realization of organic light-emitting diodes by ≪ inert ≫ ion beam assisted deposition. The used ions are Helium and Argon and the organic material is 8-tris-hydroxyquinoline aluminium which emit green light. There is no influence on the measured electroluminescence spectra but we observe notable modifications on the dark current, luminance and internal quantum efficiency versus applied bias characteristics. We discuss the different results.

Optimized organic light-emitting diodes according to deposition processes

We compare the optoelectronic properties of organic structures realized with various techniques during the deposition processes of the organic materials; among others, we present the effects of the ion beam parameters and also according to the location of the assisted area (which can be as well a part of the emitting layers as a zone of the transport layers).

Ion beam assisted deposition of organic molecules: a physical way to realize OLED structures

Abstract We demonstrate how the quantum efficiency of an organic light-emitting diode can be improved by a physical way based on the ion beam assisted deposition: the recombination current can be increased by an enhancement of the minority carrier injection while the total current can be decreased by generation of electron traps which reduced the majority current. The quantum efficiency of fluorescence can be also improved by a layer densification with a limitation of the nonradiative centers. As a result, the quantum efficiency of the structure ITO/Helium assisted Alq3/unassisted Alq3/Ca/Al is improved (by around a factor 10) in relation with a virgin structure.

Electroluminescence of parasexiphenyl prepared by ion beam assisted deposition.

Abstract Ion beams can be used in molecular or macromolecular physics to realize Organic Light Emitting Diodes (OLEDs). In order to obtain blue light emission, we have realized light emitting diodes with a conjugated oligomer : the parasexiphenyl ( 6 ). Parasexiphenyl thin film is obtained by Ion Beam Assisted Depositon (IBAD). Efficient injection of holes and electrons is provided from an ITO anode and calcium cathode. The electroluminescence spectra show that the maximum emission wavelength is not modified by IBAD process but we have noticed an increase of the resistivity.