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Effects related to the use of high power and repetition rate lasers in ablation of metals and silicon were investigated. Numeric simulation and experiments were performed to find out conditions of the efficient use of laser energy. Accumulation of defects lowers the ablation threshold when a high pulse-repetition rate is applied. An optimum beam waist exists for certain pulse energy to maximize the ablation but the waist does not allow achieving a high processing accuracy. Energy efficiency of the laser processing falls down when pulse energy exceeds the material dependant limit. Plasma shielding was assumed to be the main limiting factor in processing efficiency of metals with the high power picosecond lasers. Intelligent control of process parameters is required to keep optimal conditions for the material removal by laser ablation.

We acknowledge financial support from FP7 LAMP project “Laser Induced Synthesis of Polymeric Nanocomposite Materials and Development of Micro-patterned Hybrid Light Emitting Diodes (LED) and Transistors (LET)” (Grant No. 247928). AKB and IDWS also acknowledge financial support from EPSRC Programme grant “Challenging the limits of photonics: Structured light” EP/J01771X/1. In addition IDWS acknowledges a Royal Society Wolfson Research Merit Award. Nanostructured composites of inorganic and organic materials are attracting extensive interest for electronic and optoelectronic device applications. Here we report a novel method for the fabrication and patterning of metal selenide nanoparticles in organic semiconductor films that is compatible with solution processable large area device manufacturing. Our approach is based upon the controlled in-situ decomposition of cadmium selenide precursor complex in a film of the electron transporting material 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene (TPBI) by thermal and optical methods. Specifically we show that the photoluminescence quantum yield (PLQY) of the thermally converted CdSe quantum dots (QDs) in the TPBI film is up to 15%. We also show that laser illumination can form the QDs from the precursor. This is an important result as it enables direct laser patterning (DLP) of the QDs. DLP was performed on these nanocomposites using a picosecond laser. Confocal microscopy shows the formation of emissive QDs after laser irradiation. The optical and structural properties of the QDs were also analysed by means of UV-Vis, PL spectroscopy and transmission electron microscopy (TEM). The results show that the QDs are well distributed across the film and their emission can be tuned over a wide range by varying the temperature or irradiated laser power on the blend films. Our findings provide a route to the low cost patterning of hybrid electroluminescent devices. Publisher PDF