Project Details
Projekt
Self-Healing Inspired by Nature: Exocytosis-Like Recovering of Morphology and Optical Properties of Membranes and Interfaces Composed of Self-Assembled Luminescent Dyes
Applicant
Privatdozent Dr. Martin Presselt
Subject Area
Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
Physical Chemistry of Solids and Surfaces, Material Characterisation
Physical Chemistry of Solids and Surfaces, Material Characterisation
Term
from 2014 to 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 259571430
Nature is the ultimate inspiration source for new concepts for artificial self-healing, fabrication of functional self-assembled interfaces, solar energy conversion and many more green technologies. In the proposed project we will utilize the principle of membrane fusion of natural exocytosis for self-healing of optoelectronically active layers, exemplarily targeting a significant lifetime-extension of OLEDs (organic light emitting diodes). Therefore, we will exploit the surface activity and self-assembling of non-polar dyes which are functionalized with polar heads. These novel amphiphilic dyes are based on photo-stable thiazoles and their surface activity will be tuned systematically to optimize their driving force for exocytosis-like self-healing. Further molecular structure variations allow for adjustment of the thermodynamic equilibrium between dyes in solution and within the self-assembled active layers. The corresponding Gibbs free energy differences between dyes in these different states will be predicted via outstandingly powerful molecular modeling codes for each molecule considered for synthesis. To realize exocytosis-like self-healing at the device-level a liquid phase needs to be in physical contact with the luminescent layer, thus providing mobile fitting for exchanging damaged dyes in the active layer. Therefore, micro-basins for amphiphilic dye reservoir solutions will be provided by micro-structured substrates. For a comprehensive understanding and targeted optimization of exocytosis-like self-healing for restoring luminescence properties after damage events at the device level, we will focus on photoexcited luminescence (PL) first, before turning to OLED-lifetime optimization subsequently. This allows for investigation of the bare active layer as no electrodes are necessary in case of photoexcitation. Thus, mechanical and chemical damage can be induced and healing can be monitored online. Therefore, we will use a NIR-sensitive PL imaging setup that is optimized for the investigation of defect states. Complementary characterization of defect states via highly NIR-sensitive absorption spectroscopy and identification of PL deactivation channels by means of time-resolved PL spectros¬copy/micros¬copy forms a basis for damage-reduction via exocytosis-like self-healing. Finally, the amphiphilic dyes and device structures optimized for restoring luminescence properties will be utilized for the proof-of-concept design of OLEDs to significantly improve their lifetime. A further essential objective of the proposed work within the SPP1568 is to strengthen self-healing research by contributing and sharing our experience concerning synthesis and self-assembling of amphiphiles at interfaces, reliable modeling of their thermodynamics, characterization and deposition of highly ordered mono-layers via the Langmuir-Blodgett technique, NIR-sensitive spectroscopy for defect state characterization and fabrication of optoelectronic active device.
DFG Programme
Priority Programmes
