Periodic Reporting for period 1 - SYZEFXIS (Molecular Polaritonics: Controlling photochemistry with quantum optics)
Periodo di rendicontazione: 2023-04-01 al 2025-03-31
The SYZEFXIS research project aims to demonstrate suppression of photobleaching in organic materials using quantum optics. This will be achieved through the use of conventional as well as novel photonic architectures. Combination of inorganic and organic structures will then allow the fabrication of hybrid white-light LED devices with enhanced operational stability. The ambitious goal of achieving enhanced stability in such devices could become a stepping-stone for the development of efficient large area organic/inorganic light sources.
The key general objective of the proposed project is to control excited-state chemical reactivity via strong light-matter interactions. Photochemical reactions in organic molecular materials are very important, particularly for the development of low cost next generation optoelectronic devices for lighting, light-harvesting, visible-light communication and display technologies. Understanding the fundamental processes that limit the performance of optoelectronic devices and how such processes may be altered by the use of photonic structures will help to optimise device performance and operational stability. In addition, the use of organic semiconducting materials provides the versatility of deposition via solution-processed techniques as well as the prospect of deposition on flexible and large areas through various printing techniques. It is evident therefore, that the development of novel devices that combine cavity quantum electrodynamics and chemistry, will push the boundaries of knowledge beyond the current state-of-the-art and generate useful research and commercial opportunities.
The SYZEFXIS project aims to study the suppression of photobleaching using strong light-matter coupling in conventional and unconventional photonic devices. Photobleaching, is one of the most fundamental and important photochemical reactions, especially in organic electronic devices. Solar cells, light-emitting diodes, dye lasers etc. suffer from photobleaching which consequently limits their operational stability and performance. Most importantly, photobleaching is an irreversible event that cause permanent photo-degradation of the organic molecules. The mechanism that take place in order for the photobleaching effect to occur is associated with the interaction of excited triplet states in a molecular material with atmospheric triplet oxygen. Especially in molecules with a high intersystem crossing quantum efficiency, substantial population transfer from the singlet to the triplet excited state can enhance the photobleaching process. As the excited triplet state lifetime is relatively long, there is higher probability of the excited molecules to interact with molecular oxygen, which occurs through charge or energy transfer mechanisms. This interaction leads to the generation of various reactive oxygen species that are highly unstable and can permanently damage fluorophores through chemical reactions. It is therefore apparent how important is the suppression of photobleaching in organic molecular dyes for the development of organic optoelectronic devices with an enhanced operational stability and performance.
The key general objective of the proposed project is to control excited-state chemical reactivity via strong light-matter interactions. Photochemical reactions in organic molecular materials are very important, particularly for the development of low cost next generation optoelectronic devices for lighting, light-harvesting, visible-light communication and display technologies. Understanding the fundamental processes that limit the performance of optoelectronic devices and how such processes may be altered by the use of photonic structures will help to optimise device performance and operational stability. In addition, the use of organic semiconducting materials provides the versatility of deposition via solution-processed techniques as well as the prospect of deposition on flexible and large areas through various printing techniques. It is evident therefore, that the development of novel devices that combine cavity quantum electrodynamics and chemistry, will push the boundaries of knowledge beyond the current state-of-the-art and generate useful research and commercial opportunities.
The SYZEFXIS project aims to study the suppression of photobleaching using strong light-matter coupling in conventional and unconventional photonic devices. Photobleaching, is one of the most fundamental and important photochemical reactions, especially in organic electronic devices. Solar cells, light-emitting diodes, dye lasers etc. suffer from photobleaching which consequently limits their operational stability and performance. Most importantly, photobleaching is an irreversible event that cause permanent photo-degradation of the organic molecules. The mechanism that take place in order for the photobleaching effect to occur is associated with the interaction of excited triplet states in a molecular material with atmospheric triplet oxygen. Especially in molecules with a high intersystem crossing quantum efficiency, substantial population transfer from the singlet to the triplet excited state can enhance the photobleaching process. As the excited triplet state lifetime is relatively long, there is higher probability of the excited molecules to interact with molecular oxygen, which occurs through charge or energy transfer mechanisms. This interaction leads to the generation of various reactive oxygen species that are highly unstable and can permanently damage fluorophores through chemical reactions. It is therefore apparent how important is the suppression of photobleaching in organic molecular dyes for the development of organic optoelectronic devices with an enhanced operational stability and performance.
Significant progress have been made towards the understanding of the suppression of the photobleaching process using quantum optics. A series of Fabry-Perot microcavities have been fabricated containing different organic semiconducting materials along with their respective non-cavity control films. We have observed suppression of the photobleaching process in strongly coupled microcavities as compared to weakly coupled ones and control films and we concluded that the energy detuning of the polariton mode is also important for the suppression efficiency. Additionally we have studied the suppression of photobleaching in an unconventional structural geometry that lacks external reflective mirrors. Apart from optical structures that comprised of dielectric materials we developed a new approach for the fabrication of all solution processable free-standing organic membranes that allow for strong light-matter coupling phenomena. This type of photonic structures do not require expensive and specialized equipment such as thermal and e-beam evaporators giving the opportunity to groups with limited fabrication facilities to easily fabricate polariton devices and study polariton physics. These results have been published in the Journal of Chemical Physics. In the last part of the project, such mirror-free structures were fabricated on top of inorganic LED devices and an energy down-conversion was achieved allowing for the realisation of hybrid organic/inorganic white-light polariton LEDs.
The results obtained in the SYZEFXIS project go beyond the current state-of-the-art. Particularly, the development of the organic free-standing membrane microcavities could open up the way for cheap and simple platforms to study polariton phenomena especially in the context of polariton chemistry experiments where physical access to the strongly coupled molecules is essential. Additional research is needed to fully understand how polariton structures can be used in conjunction with mature technologies such as inorganic LEDs for the development of hybrid optoelectronic devices with enhancee operational stability by utilising the formation of polariton states.