Nonlinear Absorbing platinum(II) Acetylides for Optical Power Limiting Applications

Abstract: During the past few decades, laser technology has had a strong impact on our society, providing important contributions to materials processing, data storage, communications, medicine, and defense applications. However, the progress in laser technology has also brought about the development of harmful portable high?power lasers and tactical laser weapons. As a result, the hazard of being blinded by lasers (accidentally or from hostile use) has increased significantly. Hence, the need for protection against lasers has emerged. In order to protect optical sensors against harmful laser radiation, materials that absorb high intensity light, such as nonlinear absorbing chromophores, are employed. The concept of controlling the intensity of an optical light beam is usually referred to as optical power limiting and can be used efficiently in sensor protection devices.In this thesis, various nonlinear absorbing platinum(II) acetylides have been synthesized and characterized regarding their photophysical and optical limiting properties. Dendronized platinum(II) acetylides were prepared in order to evaluate the site isolation effect offered by the dendritic surrounding. The photophysical measurements reveal that the dendritic encapsulation enhances the phosphorescence, increases the luminescence lifetimes, and improves the optical limiting performance due to reduced quenching of the excited states.Triazole?containing chromophores were synthesized using click chemistry to achieve functionalized platinum(II) acetylides. It was found that the position of the triazole unit affects the photophysical properties of these chromophores. The most promising results were obtained for the chromophore with the triazole located at the end of the conjugation where it may act as an electron donor, thus contributing to improved two?photon absorption.A branched platinum(II) acetylide was also prepared in order to investigate the effect of multiple conjugated arms as well as multiple heavy atoms within the same molecule on the optical limiting performance. The star shaped chromophore reached the lowest clamping level of all compounds included in this thesis and constitutes a highly suitable chromophore for optical power limiting applications.The nonlinear absorbing chromophores were also incorporated into novel solid state materials based on PMMA. The actual device fabrication of doped organic glasses as optical limiters for sensor protection is presented, and their optical limiting performance is reported. The obtained organic glasses can reduce the transmission of high intensity light by 97 %.