Work Package 1

Laser thin film patterning for large area organic electronics fabrication

This work package will be led by CNRS. Emphasis will be given to the:

• Selective ablation process (one or more layer(s) removal whilst maintaining physicochemical and electrical properties of neighbouring or underlying substrate/barrier layers)
• Optimized beam delivery system (large field of view f-theta optics supporting homogenized spatial intensity beam profile on target, line focus scribing, multi-spot parallel processing, geometrical and physicochemical integrity of etched layers, i.e. sharp ablated edges free of ridges or delamination) will be investigated in depth within this WP.

Description of work

The Oxford Lasers facilities such as short and ultrashort laser pulses of different DPSS laser sources (355nm, 35ns or 10ps and 532nm, 15ns or 10ps and 1030nm, 450fs) will be employed for precision micro-patterning of thin (0.5 um < thickness layer) and nano-patterning of ultrathin (thickness layer <50 nm) (nanostructured) layers. The layers under test will be selected among common organic electronics materials such as ITO, PEDOT:PSS, Au and Ag. The samples will be prepared in stacks of one or more layers on a solid or flexible substrate using the NTUA and CNRS facilities (sputtering, spin coating, e-beam evaporation). Alternatively, the samples will be commercially purchased. In particular the special focus of this workpackage will be to identify an optimum "cold ablation" process window, whereby optimized low temperature laser processing based on primarily low intensity stress-assisted ablation phenomena, manages to remove consistently one or more targeted layers with a restricted thermal budget without any collateral damage. For this purpose several DPSS laser sources delivering short and ultra short laser pulses at a wide wavelength range (as mentioned above) will be tested to define optimum selective ablation processing conditions. Moreover, several pathways for laser spatial beam shaping will be employed to define the optimum configuration for the integration of the Laser Platform that will be conducted in WP3.
In the first WP there will be a strong interaction between the partners especially within the materials characterization sub-task. The laser micro and nano-patterned films will be originally characterized at Oxford Lasers with SEM and in collaboration with academic partners with field emission SEM, XRD, AFM and profilometer. The specific objective for the application case evaluation of the selective laser micro and nano-patterning technology is the development of organic photovoltaics. The organic electronic devices will be characterized morphologically and electrically by the experienced CNRS group.

Risk Analysis

The technical risk of this workpackage is the lack of controllable thin film patterning with thickness resolution at 50 nm. An additional risk here is the lack of reproducibility of thin film properties in terms of uniformity and adhesion. That will require an accurate selection and characterization of the samples. Their properties will depend on the manufacturing processes.