Start of funding 01.01.2010

Laserscribing of thin film transparent conductive oxides for Solar Cells and Organic Light Emitting Diodes

Prof. Dr. Ralf Hellmann
University of applied sciences Aschaffenburg

Marco Arrigoni
Coherent Inc.



Within this project a comparative study of laserscribing of thin film transparent conductive oxides will be performed for applications in the solar cell and display industry. Different laser technologies with nanosecond, picosecond and femtosecond laser pulses will be applied in the spectral range from 266nm to 1064nm to clarify the advantages of different laser sources and to identify the ideal laser processing strategy for scribing different transparent conductive oxides. For example, applying shorter laser pulses will result in a reduction of the heat affected zone and in conjunction with an increase in pulse peak power both aspects promise improved scribing results. A further objective is the identification of the relevant underlying processes for the laser-material interaction.

Final report:
Within this project a comparative study of laserscribing of thin film transparent conductive oxides was performed for applications in the solar cell and display industry. Different laser technologies with nanosecond and picosecond laser pulses have been applied in the spectral range from 266nm to 1064nm to clarify the advantages of different laser sources and to identify the ideal laser processing strategy for scribing. As a result, we demonstrated that using laser pulses in the picosecond regime for the patterning of TCO thin films for organic light emitting diodes leads to superior results, having small ridges, good groove geometries and a smooth groove bottom. This can be associated to the reduced heat affected zone due to the picosecond pulse duration. Moreover, opposite to previously published reports we have shown that the use of infrared picosecond lasers with pulse energies close to the ablation threshold leads to good laser scribing results. Hence, for industrial applications complex and cost intensive frequency conversion is superfluous.