La filière OLED (diode électroluminescente organique) est depuis quelques annéesfortement industrialisée notamment depuis leur utilisation dans les smartphones et les téléviseurs.Cependant, les procédés de fabrication, notamment l’évaporation thermique sous vide, restent coûteuxet ne peuvent pas être utilisés pour développer des applications à faible valeur ajoutée (petitsafficheurs, signalétique, éclairage). Ces travaux de thèse ont pour objectif de développer une OLEDperformante et stable fabriquée à coût réduit afin de répondre à cette problématique. La voie liquide aété privilégiée afin de diminuer les coûts de fabrication de l’OLED et il a été choisi de développer unestructure inverse pour améliorer la stabilité. Dans ce travail de thèse, le polymère PEIE(polyéthylénimine éthoxylate) a été utilisé pour diminuer le travail de sortie de la cathode transparente.Nous avons montré qu’il était possible d’atteindre des performances supérieures en structure inversequ’en structure conventionnelle à partir du même polymère émissif, le Super Yellow. Afin desimplifier le procédé de dépôt, nous avons montré qu’un mélange binaire {PEIE et matériau bloqueurde trous} pouvait être déposé en une seule fois tout en conservant un fonctionnement optimal. Uneétude par TOF-SIMS (Spectrométrie de Masse d’Ions Secondaires à Temps de Vol) a permis de mettreen évidence une ségrégation verticale du mélange binaire. Par ailleurs, l’électrode en oxyde d’étainindium(ITO), qui représente généralement plus d’un quart du coût de fabrication, a été remplacéeavec succès par une électrode de SnO2 (oxyde d’étain), déposée par ALD (dépôt de couches mincesatomiques). / OLED (Organic Light-Emitting Diode) technology has been exploited on an industrialscale for several years, principally in smartphones, TV displays, and similar devices. However, currentfabrication processes, such as thermal evaporation under high vacuum, are expensive and cannot beused for low-cost applications (signage, lighting, etc.). This work aims to develop high-performance,stable, low-cost OLEDs. Fabrication by solution processing was chosen to reduce the processing costsin any future commercialization of the work, while the inverted architecture was used to optimizedevice stability. In this work, ethoxylated polyethylenimine (PEIE) was used to reduce the workfunction of the transparent cathode. It was shown that higher performances could be obtained withinverted OLEDs compared to direct devices incorporating the same emissive polymer (Super Yellow).Furthermore, it was demonstrated that a binary blend, (PEIE and a hole blocking material) could bedeposited in a single step without reducing the OLED device’s performance – greatly simplifying thefabrication process. A TOF-SIMS (Time of Flight-Secondary Ion Mass Spectrometry) study wasconducted which demonstrated a vertical phase segregation of the binary blend. Finally, the indiumtinoxide (ITO) electrode, which represents at least 25% of the fabrication cost, was successfullyreplaced with a tin oxide (SnO2) layer, deposited by ALD (Atomic Layer Deposition).

Organic semiconductors (OSCs) present an electron mobility lower by several orders of magnitude than the hole mobility, giving rise to an electron-hole charge imbalance in organic devices such as organic light-emitting diodes (OLEDs) and organic light-emitting transistors (OLETs). In this thesis project, I tried to achieve an efficient electron transport and injection properties in opto-electronic devices, using inorganic n-type metal oxides (MOs) instead of organic n-type materials and a polyethyleneimine ethoxylated (PEIE) thin layer as electron transport (ETLs) and injection layers (EILs), respectively. In the first part of this thesis, inverted OLEDs were fabricated in order to study the effect of the PEIE layer in-between ZnO and two different emissive layers (EMLs): poly(9,9-dioctylfluorene-alt-benzothiadiazole) polymer (F8BT) and tris(8-hydroxyquinolinato) aluminum small molecule (Alq3), based on a solution and thermal evaporation processes, respectively. Different concentrations (0.80 %, 0.40 %) of PEIE layers were used to further study electron injection capability in OLEDs. After a series of optimizations in the fabrication process, the opto-electrical characterization showed high-performance of devices. The inverted OLEDs reported a maximum luminance over 104 cd m-2 and a maximum external quantum efficiency (EQE) around 1.11 %. The results were attributed to the additional PEIE layer which provided a good electron injection from MOs into EMLs. In the last part of the thesis, OLETs were fabricated and discussed by directly transferring the energy modification layer from OLEDs to OLETs. As metal oxide layer, ZnO:N was employed for OLETs since ZnO:N-based thin film transistors (TFTs) showed better performance than ZnO-based TFTs. Finally, due to their short life-time, OLETs were characterized electrically but not optically.