Abdou Karim Diallo

Pulsed-laser printing of organic thin film transistors

Organic thin-film transistors have been fabricated using laser-induced forward transfer as spatially resolved laser-printing method. Using this technique, source and drain electrodes were deposited from silver nanoparticle ink and the copper phthalocyanine (CuPc) was used to form the active layer. Both kinds of materials were transferred from a donor substrate onto a receiver substrate upon irradiation with laser pulses in the picosecond regime. The latter substrate formed the gate and the dielectric of the transistor. Electrical characterizations showed that the transistors are fully operative, showing well-defined linear and saturation regimes in the I-V curves.

Structure properties relationships of liquid crystal bent core organic semiconductors based on benzo[2,1-b:3,4-b′]dithiophene-4,5-dione

We report the synthesis of a new diketone bridged dithiophene end-capped with the mesogenic functionalities: 2,7′-bis(alkoxy-biphenyl) and 2,7′-bis(alkoxy-phenyl)-benzo[2,1-b:3,4-b′]dithiophene-4,5-dione. Optical and electrochemical properties in solution were investigated by UV-visible absorption and cyclic voltammetry. Liquid crystal properties of these new materials were investigated by differential scanning calorimetry, optical polarizing microscopy, and X-ray diffraction studies. Both compounds exhibit layered phases though there are differences in the organisation of the phase structures. Thin films were implemented as active layers into organic thin-film transistors to evaluate the charge transport properties.

Light absorption and hole-transport properties of copper corroles: from aggregates to a liquid crystal mesophase

The synthesis of the corrole-based liquid crystal phase CorLC is described together with its full characterization using a combination of Polarised Optical Microscopy (POM), ThermoGravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) measurements and Small-Angle X-Ray Diffraction (SA-XRD), which shows that CorLC has a hexagonal columnar organization at room temperature. The light absorption and hole-transport properties of the mesophase CorLC are compared with those featured by assemblies of its parent meso-triaryl (Cor1) and per-aryl (Cor2) derivatives. J-Aggregates are replaced by H-aggregates when the intermolecular distance is increased by a higher peripheral steric hindrance producing lower hole-transport mobilities.

Pulsed-Laser Printing Process for Organic Thin Film Transistors Fabrication

This paper presents a Pulsed‐Laser Printing process applied to metals, liquid, polymers and oligomers with the goal to fabricate Organic Thin‐Film Transistors. The Laser‐Induced Forward Transfer (LIFT) technique has been used as a spatially‐resolved laser deposition method. All materials have been transferred from a donor substrate onto a receiver substrate upon laser pulses in the picosecond regime. The broad nature of transferred patterns and the efficiency of the LIFT confirm the important potential of a laser printing technique in the development of the plastic microelectronics.