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Laser-induced forward transfer for the fabrication of patterned organic light-emitting diodes
| Content Provider | Semantic Scholar |
|---|---|
| Author | Lippert, Thomas Nüesch, Frank Nagel, Matthias |
| Copyright Year | 2009 |
| Abstract | The use of organic compounds as active materials in flat panel displays represents the next generation technology in the field, enabling an improved image quality, a reduced power consumption and the ability to build flexible displays. This work presents the developement of a transfer technique based on laser ablation which is aimed at the deposition of organic light-emitting diode (OLED) pixels as the building block of displays based on organic materials. The deposition technique is based on LIFT (laser-induced forward transfer), whose working principle involves a transparent substrate coated with the material to transfer. The material is irradiated through the substrate by a high power laser pulse, which triggers the removal and ejection of the material from the substrate. The ejected material is then collected onto a receiver substrate placed in front of the donor film. In this way, precise patterns defined by the shape of the laser beam can be transferred. Direct irradiation of the transfer material is not admissible for sensitive compounds, therefore a modification of the technique was introduced to solve this limitation. The modification involves the use of a sacrificial layer of a triazene polymer, which has been specifically designed for laser ablation in the ultraviolet region. The triazene layer is coated between the substrate and the transfer material, and upon irradiation, it absorbs the laser pulse, decomposes into gaseous products and propels the sensitive materials onto the receiver substrate, while protecting them from irradiation. In this work, the application of the triazene polymer as sacrificial layer for LIFT has been studied with the goal of transferring functional OLED pixels. Laser ablation of the triazene layer has been investigated over a broad thickness range and reveals that a dramatic increase of the laser energy density is required to ablate very thin films. This result is confirmed by theroretical modelling, which shows that heat diffusion into the substrate as well as the reduced absorption length play a crucial role for the ablation of very thin films. Ablation of the triazene layer from the back side has been investigated by time-resolved shadowgraphy. The ejection of a flyer of undecomposed polymer was observed, which appears when the laser fluence is not sufficient to ablate the complete layer. An analysis of the trajectories of the flyer and the shock wave created by the ablation was performed and allowed to estimate the energy balance of the process. Back side ablation of a triazene/metal film produced the ejection of a metal flyer, whose |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/151133/eth-41692-01.pdf?isAllowed=y&sequence=1 |
| Alternate Webpage(s) | https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/151133/eth-41692-02.pdf?isAllowed=y&sequence=2 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
