Florent Lefèvre

A solution processed top emission OLED with transparent carbon nanotube electrodes

Top emission organic light emitting diodes (OLEDs) with carbon nanotubes (CNTs) as top electrodes were fabricated and characterized. Devices were fabricated on glass substrates with evaporated bottom Al/LiF cathodes, a spin coated organic emissive layer and a PEDOT-PSS hole injection layer. Transparent thin CNT films were deposited on top of the emission layer to form the anode by micro-contact printing with a polydimethylsiloxane stamp. A very good device performance was obtained, with a peak luminance of 3588 cd m(-2) and a maximum current efficiency of 1.24 cd A(-1). This work shows the possibility of using CNTs as transparent electrodes to replace ITO in organic semiconductor devices. Furthermore, the top emission nature of such devices offers a broader range of applications of CNTs on any type of substrate. By combining with solution processed organic materials, it is anticipated that lower cost fabrication will be possible through roll-to-roll manufacture.

Integration of optical and electrochemical sensors on a microfluidic platform using organic optoelectronic components and silver nanowires

Since the emergence of microfluidic platforms sensors integration has been a major challenge. With the advances in miniaturization of these platforms, there is a need for solutions to integrate various optical components in order to build sensors, which will offer different detection characteristics such as several emission and sensing wavelengths. Moreover, the integration of an electrochemical sensor including a transparent electrode that will be compatible with the optical sensor represents an additional challenge. In this perspective, organic optoelectronic devices combined with silver nanowire electrodes could be a solution. The integration of a fluorescent sensor and an electrochemical oxygen sensor into a microfluidic platform and the different characteristics, advantages and disadvantages that offer organic light-emitting diodes (OLED), organic photodetectors (OPD) and silver nanowire electrodes are discussed. Finally, an example of the integration of an optical and an electrochemical sensor into a microfluidic chip for water pollution detection will be described.

Integration of polypyrrole microactuators and organic optoelectronic devices for lab-on-chip applications

Two type of devices suited for lab-on-a-chip applications were investigated. First, the integration of a polymeric microactuator deposited on top of carbon electrodes placed below a microfluidic channel. This actuator uses the out-of-plane strain of the polypyrrole/NaDBS (sodium dodecylbenzene sulfonate) system. The electrodeposition of polypyrrole on top of graphitic and carbon nanotube microelectrodes has been achieved. Secondly, the combination of an organic light emitting diode (OLED) with a microfuidic channel in order to build an integrated fluorescence detection system was also investigated.

A polymeric micro actuator to be integrated into an organic material based lab on chip microsystem

The manufacturing of a microvalve actuated by the electroactive polymer polypyrrole has been investigated. The actuator uses the electrochemically induced out-of-plane strain of the polypyrrole/NaDBS (sodium dodecylbenzene sulfonate) system. The manufacturing process of the all polymer (microfluidic channels and actuator) device has been optimized. Deposition of PPY on gold electrodes was achieved even if there is no chemical link between gold and the polymer. Delamination at the gold/PPY interface was observed after the first cycle of actuation. The use of a different electrode material to enable a chemical link between the electrode and the polymer is proposed. This type of micro actuator can easily be integrated in an all organic microsystem. It can also be assembled in series to form an integrated micropump for a disposable device.