Abstract
The requirement for flexible electronics and functional lighting has made the design of low-cost flexible optical devices increasingly important. This study proposes a novel technology for preparing a flexible substrate for OLEDs (organic light emitting diodes), based on mechanical, electrical and optical considerations. PDMS (polydimethylsiloxane) was used as the substrate of OLEDs. Meanwhile, it can be used for a light-emitting-enhancement layer and a package layer for OLEDs. This work can be organized into three main parts. First, the substrate suitable for device fabrication was developed by mixing the PDMS substrate with various nanoparticles, to optimize the CTE (coefficient of thermal expansion) and hardness. Embedding the Al2O3 nanocomposite layer nearer the PDMS surface showed the best improvement on surface hardness. Second, a mesh structure on the emitting surface to enhance the external quantum efficiency and its fabrication process that can be applied for a large-area device with low production cost were developed. This mesh structure can be integrated with the Al2O3-embedded PDMS substrate and the electroluminance of the OLED under mechanical strain was examined. The experimental results indicate that the PDMS-based substrate with the optical structures can be successfully realized for FOLEDs (flexible organic light emitting diodes). However, such FOLEDs still suffer from short lifetime and bending instability due to relatively large CTE. Possible solutions are proposed to make this system more robust in FOLEDs applications.