A structure property relationship relating photostability with the axial and peripheral substituents of Boronsubphthalocyanine (BsubPc) derivatives has been outlined: peripherally halogenating BsubPc has been determined to be the best way to increase the photostability, while axial substituents are found to have little effect. A solid state photostability test using BsubPc doped polymer films has been developed and was used to form this structure property relationship. The polymer in which BsubPc is tested is found to have an effect on the photostability and should be further explored. In addition to the structure property relationship, processes to make new BsubPc precursors, HO-BsubPc and Br-BsubPc, have been developed in order to further expand the derivatives available for study.

A structure property relationship relating photostability with the axial and peripheral substituents of Boronsubphthalocyanine (BsubPc) derivatives has been outlined: peripherally halogenating BsubPc has been determined to be the best way to increase the photostability, while axial substituents are found to have little effect. A solid state photostability test using BsubPc doped polymer films has been developed and was used to form this structure property relationship. The polymer in which BsubPc is tested is found to have an effect on the photostability and should be further explored. In addition to the structure property relationship, processes to make new BsubPc precursors, HO-BsubPc and Br-BsubPc, have been developed in order to further expand the derivatives available for study.

Boronsubphthalocyanines (BsubPcs) are a class of organic semiconducting materials which are relatively underdeveloped in their synthetic methods and organic semiconducting applications. A comprehensive investigation of these materials is explored in a rigorous and strategic manner progressing through each stage of the materials development cycle: materials selection from computational screening, organic/organometallic synthesis of target materials using known methods or by the development of new synthetic methods, physical and chemical analysis of new materials, and device implementation in organic light emitting diodes and organic photovoltaic cells. The result is the formation of new compositions of BsubPc specifically engineered for application as organic semiconductors in devices. Specifically, phenoxy-boronsubphthalocyanine derivatives are investigated starting with a computational study of their molecular orbitals – a property that dictates their function (donor or acceptor behaviour) in organic electronic devices. The nature of the axial phenoxylate is found to vary the energy level of the frontier molecular orbitals minimally, by up to ~0.4 eV while the nature of the BsubPc periphery can shift the energy levels of the frontier molecular orbitals by >1 eV. The differential sensitivity of the axial phenoxylate and the BsubPc periphery becomes a key design element allowing controlled adjustments of the frontier molecular orbitals by peripheral modification and isolating the design physical chemical properties essential to device fabrication to the axial phenoxylate. Subsequently, an investigation into the solubility and sublimability of these materials is performed, which leads to their investigation in OLED and OPV devices. The success from the phenoxy-BsubPcs study has led to the exploration of new chemistry to expand the available axial nucleophiles beyond phenoxylates. Previously unattainable sulphur and nitrogen nucleophiles are synthesised using two methods (1) the condensation of Cl-BsubPc with phthalimides and (2) the activation of Cl-BsubPc using aluminum chloride to access thiols and anilines. The phthalimido-BsubPcs synthesized from this method are incorporated in OLEDs.

Boronsubphthalocyanines (BsubPcs) are a class of organic semiconducting materials which are relatively underdeveloped in their synthetic methods and organic semiconducting applications. A comprehensive investigation of these materials is explored in a rigorous and strategic manner progressing through each stage of the materials development cycle: materials selection from computational screening, organic/organometallic synthesis of target materials using known methods or by the development of new synthetic methods, physical and chemical analysis of new materials, and device implementation in organic light emitting diodes and organic photovoltaic cells. The result is the formation of new compositions of BsubPc specifically engineered for application as organic semiconductors in devices. Specifically, phenoxy-boronsubphthalocyanine derivatives are investigated starting with a computational study of their molecular orbitals – a property that dictates their function (donor or acceptor behaviour) in organic electronic devices. The nature of the axial phenoxylate is found to vary the energy level of the frontier molecular orbitals minimally, by up to ~0.4 eV while the nature of the BsubPc periphery can shift the energy levels of the frontier molecular orbitals by >1 eV. The differential sensitivity of the axial phenoxylate and the BsubPc periphery becomes a key design element allowing controlled adjustments of the frontier molecular orbitals by peripheral modification and isolating the design physical chemical properties essential to device fabrication to the axial phenoxylate. Subsequently, an investigation into the solubility and sublimability of these materials is performed, which leads to their investigation in OLED and OPV devices. The success from the phenoxy-BsubPcs study has led to the exploration of new chemistry to expand the available axial nucleophiles beyond phenoxylates. Previously unattainable sulphur and nitrogen nucleophiles are synthesised using two methods (1) the condensation of Cl-BsubPc with phthalimides and (2) the activation of Cl-BsubPc using aluminum chloride to access thiols and anilines. The phthalimido-BsubPcs synthesized from this method are incorporated in OLEDs.

The original goal of this thesis was to develop process chemistry to yield boron subphthalocyanine (BsubPc) derivatives which were previously difficult to access. Retrospectively, it was found that these compounds show extremely high density crystal packing in comparison to other known BsubPcs, and thus this also became a focus of the thesis. A process to synthesize and purify fluoro-BsubPc was developed. This led to a detailed comparison of the physical and chemical properties of the three halo-BsubPcs in order to answer the question of which halo-BsubPc is appropriate for different purposes. Through this work, the previously unpublished crystal structure of the oxygen bridged dimer, µ-oxo-BsubPc, was found. A process was subsequently developed for the practical synthesis of µ-oxo-BsubPc for use in vacuum deposition and a number of µ-oxo-BsubPc crystal polymorphs were found and analyzed. The properties of this group of compounds are discussed in the context of other known BsubPcs.

The original goal of this thesis was to develop process chemistry to yield boron subphthalocyanine (BsubPc) derivatives which were previously difficult to access. Retrospectively, it was found that these compounds show extremely high density crystal packing in comparison to other known BsubPcs, and thus this also became a focus of the thesis. A process to synthesize and purify fluoro-BsubPc was developed. This led to a detailed comparison of the physical and chemical properties of the three halo-BsubPcs in order to answer the question of which halo-BsubPc is appropriate for different purposes. Through this work, the previously unpublished crystal structure of the oxygen bridged dimer, µ-oxo-BsubPc, was found. A process was subsequently developed for the practical synthesis of µ-oxo-BsubPc for use in vacuum deposition and a number of µ-oxo-BsubPc crystal polymorphs were found and analyzed. The properties of this group of compounds are discussed in the context of other known BsubPcs.

Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this dissertation I report investigations of novel materials and the underlying principles of organic solar cells, carried out at the University of St Andrews between 2011 and 2015. Key results of this investigation: • The charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC₇₁BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved. • Subphthalocyanine molecules, which are commonly used as electron donor materials in vacuum-deposited active layers of organic solar cells, can, by a slight structural modification, also be used as efficient electron acceptor materials in solution-deposited active layers. Additionally these acceptors offer, compared to standard fullerene acceptors,advantages of a stronger light absorption at the peak of the solar spectrum. • A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage. • Metal structures in nanometer-size can efficiently enhance the electric field and light absorption in organic semiconductors by plasmonic resonance. The fluorescence of a P3HT polymer film above silver nanowires, separated by PEDOT:PSS, increased by factor of two. This could be clearly assigned to an enhanced absorption as the radiative transition of P3HT was identical beside the nanowires. • The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC₇₁BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.

博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

Der Gegenstand der vorliegenden Arbeit ist die Untersuchung von photoinduzierten Energietransferprozessen (EET) und Elektronentransferprozessen (ET) in Modellsystemen, die als potentiell geeignet für eine Nutzung in der artifiziellen Photosynthese angesehen werden. Den beiden wesentlichen Zugängen zur Architektur artifizieller Photosynthese-Systeme entsprechend wurden vergleichend kovalente und sich selbst organisierende Systeme untersucht. In beiden Zugängen wurden ähnliche chemische Komponenten als optisch aktive Moleküle eingesetzt, insbesondere Phthalocyanine mit einem Silizium-Zentralatom (SiPc). Durch eine Kombination von stationären und zeitaufgelösten optisch-spektroskopischen Methoden konnten die lichtinduzierten ET- und EET-Prozesse identifiziert und quantifiziert werden. Im ersten Teil der Arbeit wurden mehrere kovalent gebundene Triaden und eine Pentade untersucht. In allen Systemen finden sehr effiziente ET und EET Prozesse statt. Es wurde gezeigt, dass das Lösungsmittel großen Einfluss auf die photophysikalischen Eigenschaften der Systeme ausübt. Die Lebensdauer des ladungsseparierten Zustandes variiert von 1,7 ns in Toluol bis 30 ps in DMF. Im zweiten Teil der Arbeit wurde erstmals gezeigt, dass sich in wässriger Lösung ein supramolekularer Komplex, bestehend aus einem Beta-Cyklodextrin (CD), einem konjugierten Subphthylocyanin (SubPc), einem Porphyrin (Por) und einem SiPc bilden kann. Letzteres wurde über unterschiedliche Ketten an zwei CDs kovalent gebunden. Die Selbstorganisation wird über hydrophobe Wechselwirkungen vermittelt und die Bildung der Komplexe ist sehr effizient. Nach selektiver Anregung von SubPc finden sequenzielle ET- und EET-Prozesse von SubPc zu SiPc statt. Das Por spielt die Rolle einer energetischen und elektronischen Brücke und ermöglicht die ET und EET-Prozesse von SubPc zu SiPc. Die Ladungsrekombination in den Grundzustand geschieht innerhalb von 1,7 ns. / The main objective of the present thesis was to conduct investigations of photo-induced electron transfer (ET) and excitation energy transfer (EET) processes in model compounds that are considered potentially appropriate for use in artificial photosynthesis. Two approaches have been used to construct the artificial photosynthetic systems, namely covalent and supramolecular approach. In both systems similar optically active molecules have been employed, particularly silicon-based phthalocyanines (SiPc). A comparative study between the covalently-linked and self-assembled systems had been conducted. For these purposes, thorough spectroscopic measurements in the UV/Vis range had been performed on these conjugates. A combination of steady-state and time-resolved experiments allowed an identification and quantification of the photo-induced ET and EET processes. In the first part of the work several covalently bound triads and a pentad bearing a central SiPc unit were studied. In all systems highly efficient ET and EET processes take place. It was found that the solvent exerts great influence on the photophysical properties of the systems. The lifetime of the charge-separated state varied from 1.7 ns (toluene) down to 30 ps (DMF). In the second part of the thesis, for the first time the formation of ternary supramolecular complexes consisting of a beta-cyclodextrin (CD), a conjugated subphthalocyanine (SubPc), a porphyrin (Por) and a series of SiPcs substituted axially with two CDs via different spacers was shown. These components are held in water by host-guest interactions and the formation of these host-guest complexes was found to be very efficient. Upon excitation of the SubPc-part of the complex sequential ET and EET processes from SubPc to SiPc take place. The Por dye acts as a transfer bridge enabling these processes. The probability of ET is controlled by the linker between CD and SiPc. Charge recombination to the ground state occurs within 1.7 ns.