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The CH2Cl2/MeOH (1:1) extract of Zanthoxylum holstzianum stem bark showed good antiplasmodial activity (IC50 2.5 +/- 0.3 and 2.6 +/- 0.3 mu g/mL against the W2 and D6 strains of Plasmodium falciparum, respectively). From the extract five benzophenanthridine alkaloids [8-acetonyldihydrochelerythrine (1), nitidine (2), dihydrochelerythine (3), norchelerythrine (5), arnottianamide (8)]; a 2-quinolone alkaloid [N-methylflindersine (4)]; a lignan [4,4 '-dihydroxy-3,3 '-dimethoxylignan-9,9 '-diyl diacetate (7)] and a dimer of a benzophenanthridine and 2-quinoline [holstzianoquinoline (6)] were isolated. The CH2Cl2/MeOH (1:1) extract of the root bark afforded 1, 3-6, 8, chelerythridimerine (9) and 9-demethyloxychelerythrine (10). Holstzianoquinoline (6) is new, and is the second dimer linked by a C-C bond of a benzophenanthridine and a 2-quinoline reported thus far. The compounds were identified based on spectroscopic evidence. Amongst five compounds (1-5) tested against two strains of P. falciparum, nitidine (IC50 0.11 +/- 0.01 mu g/mL against W2 and D6 strains) and norchelerythrine (IC50 value of 0.15 +/- 0.01 mu g/mL against D6 strain) were the most active.
The urge of light utilization in fabrication of materials is as encouraging as challenging. Steadily increasing energy consumption in accordance with rapid population growth, is requiring a corresponding solution within the same rate of occurrence speed. Therefore, creating, designing and manufacturing materials that can interact with light and in further be applicable as well as disposable in photo-based applications are very much under attention of researchers. In the era of sustainability for renewable energy systems, semiconductor-based photoactive materials have received great attention not only based on solar and/or hydrocarbon fuels generation from solar energy, but also successful stimulation of photocatalytic reactions such as water splitting, pollutant degradation and organic molecule synthesisThe turning point had been reached for water splitting with an electrochemical cell consisting of TiO2-Pt electrode illuminated by UV light as energy source rather than an external voltage, that successfully pursued water photolysis by Fujishima and Honda in 1972. Ever since, there has been a great deal of interest in research of semiconductors (e.g. metal oxide, metal-free organic, noble-metal complex) exhibiting effective band gap for photochemical reactions. In the case of environmental friendliness, toxicity of metal-based semiconductors brings some restrictions in possible applications. Regarding this, very robust and ‘earth-abundant’ organic semiconductor, graphitic carbon nitride has been synthesized and successfully applied in photoinduced applications as novel photocatalyst. Properties such as suitable band gap, low charge carrier recombination and feasibility for scaling up, pave the way of advance combination with other catalysts to gather higher photoactivity based on compatible heterojunction.
This dissertation aims to demonstrate a series of combinations between organic semiconductor g-CN and polymer materials that are forged through photochemistry, either in synthesis or in application. Fabrication and design processes as well as applications performed in accordance to the scope of thesis will be elucidated in detail. In addition to UV light, more attention is placed on visible light as energy source with a vision of more sustainability and better scalability in creation of novel materials and solar energy based applications.
Carbon nitride semiconductors: properties and application as photocatalysts in organic synthesis
(2023)
Graphitic carbon nitrides (g-CNs) are represented by melon-type g-CN, poly(heptazine imides) (PHIs), triazine-based g-CN and poly(triazine imide) with intercalated LiCl (PTI/Li+Cl‒). These materials are composed of sp2-hybridized carbon and nitrogen atoms; C:N ratio is close to 3:4; the building unit is 1,3,5-triazine or tri-s-triazine; the building units are interconnected covalently via sp2-hybridized nitrogen atoms or NH-moieties; the layers are assembled into a stack via weak van der Waals forces as in graphite. Due to medium band gap (~2.7 eV) g-CNs, such as melon-type g-CN and PHIs, are excited by photons with wavelength ≤ 460 nm. Since 2009 g-CNs have been actively studied as photocatalysts in evolution of hydrogen and oxygen – two half-reactions of full water splitting, by employing corresponding sacrificial agents. At the same time application of g-CNs as photocatalysts in organic synthesis has been remaining limited to few reactions only. Cumulative Habilitation summarizes research work conducted by the group ‘Innovative Heterogeneous Photocatalysis’ between 2017-2023 in the field of carbon nitride organic photocatalysis, which is led by Dr. Oleksandr Savatieiev.
g-CN photocatalysts activate molecules, i.e. generate their more reactive open-shell intermediates, via three modes: i) Photoinduced electron transfer (PET); ii) Excited state proton-coupled electron transfer (ES-PCET) or direct hydrogen atom transfer (dHAT); iii) Energy transfer (EnT). The scope of reactions that proceed via oxidative PET, i.e. one-electron oxidation of a substrate to the corresponding radical cation, are represented by synthesis of sulfonylchlorides from S-acetylthiophenols. The scope of reactions that proceed via reductive PET, i.e. one-electron reduction of a substrate to the corresponding radical anion, are represented by synthesis of γ,γ-dichloroketones from the enones and chloroform.
Due to abundance of sp2-hybridized nitrogen atoms in the structure of g-CN materials, they are able to cleave X-H bonds in organic molecules and store temporary hydrogen atom. ES-PCET or dHAT mode of organic molecules activation to the corresponding radicals is implemented for substrates featuring relatively acidic X-H bonds and those that are characterized by low bond dissociation energy, such as C-H bond next to the heteroelements. On the other hand, reductively quenched g-CN carrying hydrogen atom reduces a carbonyl compound to the ketyl radical via PCET that is thermodynamically more favorable pathway compared to the electron transfer. The scope of these reactions is represented by cyclodimerization of α,β-unsaturated ketones to cyclopentanoles.
g-CN excited state demonstrates complex dynamics with the initial formation of singlet excited state, which upon intersystem crossing produces triplet excited state that is characterized by the lifetime > 2 μs. Due to long lifetime, g-CN activate organic molecules via EnT. For example, g-CN sensitizes singlet oxygen, which is the key intermediate in the dehydrogenation of aldoximes to nitrileoxides. The transient nitrileoxide undergoes [3+2]-cycloaddition to nitriles and gives oxadiazoles-1,2,4.
PET, ES-PCET and EnT are fundamental phenomena that are applied beyond organic photocatalysis. Hybrid composite is formed by combining conductive polymers, such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with potassium poly(heptazine imide) (K-PHI). Upon PET, K-PHI modulated population of polarons and therefore conductivity of PEDOT:PSS. The initial state of PEDOT:PSS is recovered upon material exposure to O2. K-PHI:PEDOT:PSS may be applied in O2 sensing.
In the presence of electron donors, such as tertiary amines and alcohols, and irradiation with light, K-PHI undergoes photocharging – the g-CN material accumulates electrons and charge-compensating cations. Such photocharged state is stable under anaerobic conditions for weeks, but at the same time it is a strong reductant. This feature allows decoupling in time light harvesting and energy storage in the form of electron-proton couples from utilization in organic synthesis. The photocharged state of K-PHI reduces nitrobenzene to aniline, and enables dimerization of α,β-unsaturated ketones to hexadienones in dark.
Solar photocatalysis is the one of leading concepts of research in the current paradigm of sustainable chemical industry. For actual practical implementation of sunlight-driven catalytic processes in organic synthesis, a cheap, efficient, versatile and robust heterogeneous catalyst is necessary. Carbon nitrides are a class of organic semiconductors who are known to fulfill these requirements.
First, current state of solar photocatalysis in economy, industry and lab research is overviewed, outlining EU project funding, prospective synthetic and reforming bulk processes, small scale solar organic chemistry, and existing reactor designs and prototypes, concluding feasibility of the approach.
Then, the photocatalytic aerobic cleavage of oximes to corresponding aldehydes and ketones by anionic poly(heptazine imide) carbon nitride is discussed. The reaction provides a feasible method of deprotection and formation of carbonyl compounds from nitrosation products and serves as a convenient model to study chromoselectivity and photophysics of energy transfer in heterogeneous photocatalysis.
Afterwards, the ability of mesoporous graphitic carbon nitride to conduct proton-coupled electron transfer was utilized for the direct oxygenation of 1,3-oxazolidin-2-ones to corresponding 1,3-oxazlidine-2,4-diones. This reaction provides an easier access to a key scaffold of diverse types of drugs and agrochemicals.
Finally, a series of novel carbon nitrides based on poly(triazine imide) and poly(heptazine imide) structure was synthesized from cyanamide and potassium rhodizonate. These catalysts demonstrated a good performance in a set of photocatalytic benchmark reactions, including aerobic oxidation, dual nickel photoredox catalysis, hydrogen peroxide evolution and chromoselective transformation of organosulfur precursors.
Concluding, the scope of carbon nitride utilization for net-oxidative and net-neutral photocatalytic processes was expanded, and a new tunable platform for catalyst synthesis was discovered.
Its properties make copper one of the world’s most important functional metals. Numerous megatrends are increasing the demand for copper. This requires the prospection and exploration of new deposits, as well as the monitoring of copper quality in the various production steps. A promising technique to perform these tasks is Laser Induced Breakdown Spectroscopy (LIBS). Its unique feature, among others, is the ability to measure on site without sample collection and preparation. In this work, copper-bearing minerals from two different deposits are studied. The first set of field samples come from a volcanogenic massive sulfide (VMS) deposit, the second part from a stratiform sedimentary copper (SSC) deposit. Different approaches are used to analyze the data. First, univariate regression (UVR) is used. However, due to the strong influence of matrix effects, this is not suitable for the quantitative analysis of copper grades. Second, the multivariate method of partial least squares regression (PLSR) is used, which is more suitable for quantification. In addition, the effects of the surrounding matrices on the LIBS data are characterized by principal component analysis (PCA), alternative regression methods to PLSR are tested and the PLSR calibration is validated using field samples.
Its properties make copper one of the world’s most important functional metals. Numerous megatrends are increasing the demand for copper. This requires the prospection and exploration of new deposits, as well as the monitoring of copper quality in the various production steps. A promising technique to perform these tasks is Laser Induced Breakdown Spectroscopy (LIBS). Its unique feature, among others, is the ability to measure on site without sample collection and preparation. In this work, copper-bearing minerals from two different deposits are studied. The first set of field samples come from a volcanogenic massive sulfide (VMS) deposit, the second part from a stratiform sedimentary copper (SSC) deposit. Different approaches are used to analyze the data. First, univariate regression (UVR) is used. However, due to the strong influence of matrix effects, this is not suitable for the quantitative analysis of copper grades. Second, the multivariate method of partial least squares regression (PLSR) is used, which is more suitable for quantification. In addition, the effects of the surrounding matrices on the LIBS data are characterized by principal component analysis (PCA), alternative regression methods to PLSR are tested and the PLSR calibration is validated using field samples.
The increasing global population has led to a growing demand for cost-effective and eco-friendly methods of water purification. This demand has reached a peak due to the increasing presence of impurities and pollutants in water and a growing awareness of waterborne diseases. Advanced oxidation processes (AOPs) are effective methods to address these challenges, due to the generation of highly reactive radicals, such as sulfate radical (SO4•-), hydroxyl radical (•OH), and/or superoxide radical (•O2-) in oxidation reactions. Relative to conventional hydrogen peroxide (H2O2)-based AOPs for wastewater treatment, the persulfate-related AOPs are receiving increasing attention over the past decades, due to their stronger oxidizing capability and a wider pH working window. Further deployment of the seemingly plausible technology as an alternative for the well-established one in industry, however, necessitates a careful evaluation of compounding factors, such as water matrix effects, toxicological consequences, costs, and engineering challenges, etc. To this end, rational design of efficient and environmentally friendly catalysts constitutes an indispensable pathway to advance persulfate activation efficacy and to elucidate the mechanisms in AOPs, the combined endeavors are expected to provide insightful understanding and guidelines for future studies in wastewater treatment. A dozens of transition metal-based catalysts have been developed for persulfate-related AOPs, while the undesirable metal leaching and poor stability in acidic conditions have been identified as major obstacles. Comparatively, the carbonaceous materials are emerging as alternative candidates, which are characterized by metal-free nature, wide availability, and exceptional resistance to acid and alkali, as well as tunable physicochemical and electronic properties, the combined merits make them an attractive option to overcome the aforementioned limitations in metal-based catalytic systems. This dissertation aims at developing novel carbonaceous materials to boost the activity in peroxymonosulfate (PMS) activation processes. Functionalized carbon materials with metal particles or heteroatoms were constructed and further evaluated in terms of their ability to activate PMS for AOPs. The main contents of this thesis are summarized as follows: (1) Iron oxide-loaded biochar: improving stability and alleviating metal leakage Metal leaching constitutes one of the main drawbacks in using transition metals as PMS activators, which is accompanied by the generation of metal-containing sludge, potentially leading to secondary pollution. Meanwhile, the metal nanoparticles are prone to aggregate, causing rapid decay of catalytic performance. The use of carbons as supports for transition metals could mitigate these deficiencies, because the interaction between metals and carbons could in turn disperse and stabilize metal nanoparticles, thus suppressing the metal leaching. In this work, the environmentally benign lignin with its abundant phenolic groups, which is well known to serve as carbon source with high yields and flexibility, was utilized to load Fe ions. The facile low-temperature pre-treatment pyrolytic strategy was employed to construct a green catalyst with iron oxides embedded in Kraft-lignin-derived biochar (termed as γ-Fe2O3@KC). The γ-Fe2O3@KC was capable of activating PMS to generate stable non-radical species (1O2 and Fe (V)=O) and to enhance electron transfer efficiency. A surface-bound reactive complex (catalyst-PMS*) was identified by electrochemical characterizations and discussed with primary surface-bound radical pairs to explain the contradictions between quenching and EPR detection results. The system also showed encouraging reusability for at least 5 times and high stability at pH 3-9. The low concentration of iron in γ-Fe2O3@KC/PMS system implied that the carbon scaffold of biochar substantially alleviated metal leakage. (2) MOF-derived nanocarbon: new carbon crystals Traditional carbon materials are of rather moderate performance in activation PMS, due to the poor electron transfer capacity within the amorphous structure and limited active sites for PMS adsorption. Herein, we established crystalline nanocarbon materials via a simple NaCl-templated strategy using the monoclinic zeolitic imidazolate framework-8 (ZIF-8) sealed with NaCl crystals as the precursors. Specifically, NaCl captured dual advantages in serving as structure-directing agent during hydrolysis and protective salt reactor to facilitate phase transformation during carbonization. The structure-directing agent NaCl provided a protective and confined space for the evolution of MOF upon carbonization, which led to high doping amounts of nitrogen (N) and oxygen elements (O) in carbon framework (N: 14.16 wt%, O: 9.6 wt%) after calcination at a high temperature of 950 oC. We found that N-O co-doping can activate the chemically inert carbon network and the nearby sp2-hybridized carbon atoms served as active sites for adsorption and activation. Besides, the highly crystallized structure with well-established carbon channels around activated carbon atoms could significantly accelerate electron transfer process after initial adsorption of PMS. As such, this crystalline nanocarbon exhibited excellent catalytic kinetics for various pollutants. (3) MOF-derived 2D carbon layers: enhanced mass/electron transfer The two-dimensional (2D) configuration of carbon-based nanosheets with inherent nanochannels and abundant active sites residing on the layer edges or in between the layers, allowed the accessible interaction and close contact between the substrates and reactants, as well as the dramatically improved electron- and mass-transfer kinetics. In this regard, we developed dual-templating strategy to afford 2D assembly of the crystalline carbons, which found efficiency in reinforcing the interactions between the catalyst surface and foreign pollutants. Specifically, we found that the ice crystals and NaCl promoted the evolution of MOF in a 2D fashion during the freezing casting stage, while the later further allowed the formation of a graphitic surface at high calcination temperature, by virtue of the templating effect of molten salt. Due to the highly retained co-doping amounts, N and O heteroatoms created abundant active sites for PMS activation, the 2D configuration of carbon-based nanosheets enable efficient interaction of PMS and pollutants on the surface, which further boosted the kinetics of degradation.
Im Rahmen dieser Arbeit wurden Energie induzierte Nanopartikel-Substrat Interaktionen untersucht. Dazu wurden Goldnanopartikelanordnungen (AuNPA) auf verschiedenen Silizium-basierten Substraten hergestellt und der Einfluss eines Energieeintrages, genauer gesagt einer thermischen Behandlung oder des Metall-assistierten chemischen Ätzens (MaCE) getestet. Die Nanopartikelanordnungen, welche für die thermische Behandlung eingesetzt wurden, wurden nass-chemisch in Toluol synthetisiert, mit Thiol-terminiertem Polystyrol funktionalisiert und mittels Schleuderbeschichtung auf verschiedenen Substraten (drei Gläser und ein Siliziumwafer) in quasi-hexagonalen Mustern angeordnet. Diese AuNP-Anordnungen wurden mit Temperaturen zwischen 475 °C – 792 °C über verschiedene Zeiträume thermisch behandelt. Generell sanken die Nanopartikel in die Substrate ein, und es wurde festgestellt, dass mit Erhöhung der Glasübergangstemperatur der Substrate die Einsinktiefe der Nanopartikel abnahm. Die AuNPA auf Siliziumwafern wurden auf Temperaturen von 700 °C – 900 °C erhitzt. Die Goldnanopartikel sanken dabei bis zu 2,5 nm in das Si-Substrat ein. Ein Sintern der Nanopartikel fand ab einer Temperatur über 660 °C statt. Welcher Sintermechanismus der dominante ist konnte abschließend nicht eindeutig geklärt werden.
Für die Untersuchung des Einflusses des zweiten Energieeintrages mittels MaCE wurden AuNPA sowie Goldkern-Silberschale-Anordnungen auf Siliziumsubstraten genutzt. Die AuNPA wurden mit Hilfe von Poly-N-Isopropylacrylamid Mikrogelen und Natriumcitrat-stabilisierten Goldnanopartikeln (Na-AuNP) bzw. Tetrachloridogoldsäure (TCG) präpariert. Es ergaben sich Nanopartikelanordnungen mit hemisphärischen Partikeln (aus Na-AuNP) und zum anderen Nanopartikelanordnungen mit sphärischen Partikeln (aus TCG). Durch eine anschließende Silberwachstumsreaktion konnten dann die dazugehörigen Goldkern-Silberschale Nanopartikelanordnungen erhalten werden. Beim MaCE konnten signifikante Unterschiede im Verhalten dieser vier Nanopartikelanordnungen festgestellt werden, z.B. mussten bei den hemisphärischen Partikelanordnungen höhere Wasserstoffperoxidkonzentrationen (0,70 M – 0,91 M) als bei den sphärischen Partikelanordnungen (0,08 M – 0,32 M) für das Ätzen eingesetzt werden, um ein Einsinken der Nanopartikel in das Substrat zu erreichen.
The retention of actinides in different oxidation states (An(X), X = III, IV, VI) by a calcium-silicate-hydrate (C-S-H) phase with a Ca/Si (C/S) ratio of 0.8 was investigated in the presence of gluconate (GLU). The actinides considered were Am(III), Th(IV), Pu(IV), and U(VI). Eu(III) was investigated as chemical analogue for Am(III) and Cm(III). In addition to the ternary systems An(X)/GLU/C-S-H, also binary systems An(X)/C-S-H, GLU/C-S-H, and An(X)/GLU were studied. Complementary analytical techniques were applied to address the different specific aspects of the binary and ternary systems. Time-resolved laser-induced luminescence spectroscopy (TRLFS) was applied in combination with parallel factor analysis (PARAFAC) to identify retained species and to monitor species-selective sorption kinetics. ¹³C and ²⁹Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied to determine the bulk structure and the composition of the C-S-H surface, respectively, in the absence and presence of GLU. The interaction of Th(IV) with GLU in different electrolytes was studied by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The influence of GLU on An(X) retention was investigated for a large concentration range up to 10⁻² M. The results showed that GLU had little to no effect on the overall An(X) retention by C-S-H with C/S of 0.8, regardless of the oxidation state of the actinides. For Eu(III), the TRLFS investigations additionally implied the formation of a Eu(III)-bearing precipitate with dissolved constituents of the C-S-H phase, which becomes structurally altered by the presence of GLU. For U(VI) sorption on the C-S-H phase, only a small influence of GLU could be established in the luminescence spectroscopic investigations, and no precipitation of U(VI)-containing secondary phases could be identified.
The retention of actinides in different oxidation states (An(X), X = III, IV, VI) by a calcium-silicate-hydrate (C-S-H) phase with a Ca/Si (C/S) ratio of 0.8 was investigated in the presence of gluconate (GLU). The actinides considered were Am(III), Th(IV), Pu(IV), and U(VI). Eu(III) was investigated as chemical analogue for Am(III) and Cm(III). In addition to the ternary systems An(X)/GLU/C-S-H, also binary systems An(X)/C-S-H, GLU/C-S-H, and An(X)/GLU were studied. Complementary analytical techniques were applied to address the different specific aspects of the binary and ternary systems. Time-resolved laser-induced luminescence spectroscopy (TRLFS) was applied in combination with parallel factor analysis (PARAFAC) to identify retained species and to monitor species-selective sorption kinetics. ¹³C and ²⁹Si magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were applied to determine the bulk structure and the composition of the C-S-H surface, respectively, in the absence and presence of GLU. The interaction of Th(IV) with GLU in different electrolytes was studied by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS). The influence of GLU on An(X) retention was investigated for a large concentration range up to 10⁻² M. The results showed that GLU had little to no effect on the overall An(X) retention by C-S-H with C/S of 0.8, regardless of the oxidation state of the actinides. For Eu(III), the TRLFS investigations additionally implied the formation of a Eu(III)-bearing precipitate with dissolved constituents of the C-S-H phase, which becomes structurally altered by the presence of GLU. For U(VI) sorption on the C-S-H phase, only a small influence of GLU could be established in the luminescence spectroscopic investigations, and no precipitation of U(VI)-containing secondary phases could be identified.
Lithium-ion capacitors (LICs) are promising energy storage devices by asymmetrically combining anode with a high energy density close to lithium-ion batteries and cathode with a high power density and long-term stability close to supercapacitors. For the further improvement of LICs, the development of electrode materials with hierarchical porosity, nitrogen-rich lithiophilic sites, and good electrical conductivity is essential. Nitrogen-rich all-carbon composite hybrids are suitable for these conditions along with high stability and tunability, resulting in a breakthrough to achieve the high performance of LICs. In this thesis, two different all-carbon composites are suggested to unveil how the pore structure of lithiophilic composites influences the properties of LICs. Firstly, the composite with 0-dimensional zinc-templated carbon (ZTC) and hexaazatriphenylene-hexacarbonitrile (HAT) is examined how the pore structure is connected to Li-ion storage property as LIC electrode. As the pore structure of HAT/ZTC composite is easily tunable depending on the synthetic factor and ratio of each component, the results will allow deeper insights into Li-ion dynamics in different porosity, and low-cost synthesis by optimization of the HAT:ZTC ratio. Secondly, the composite with 1-dimensional nanoporous carbon fiber (ACF) and cost-effective melamine is proposed as a promising all-carbon hybrid for large-scale application. Since ACF has ultra-micropores, the numerical structure-property relationships will be calculated out not only from total pore volume but more specifically from ultra-micropore volume. From these results above, it would be possible to understand how hybrid all-carbon composites interact with lithium ions in nanoscale as well as how structural properties affect the energy storage performance. Based on this understanding derived from the simple materials modeling, it will provide a clue to design the practical hybrid materials for efficient electrodes in LICs.
We live in an era driven by fossil fuels. The prevailing climate change suggests that we have to significantly reduce greenhouse gas emissions. The only way forward is to use renewable energy sources. Among those, solar energy is a clean, affordable, and sustainable source of energy. It has the potential to satisfy the world’s energy demand in the future. However, there is a need to develop new materials that can make solar energy usable. Photovoltaics (PV) are devices that convert photon energy into electrical energy. The most commonly used solar cells are based on crystalline silicon. However, the fabrication process for silicon solar cells is technologically difficult and costly. Solar cells based on lead halide perovskites (PSCs) have emerged as a new candidate for PV applications since 2009. To date, PSCs have achieved 26% power-conversion-efficiency (PCE) for its single junction, and 33.7% PCE for tandem junction devices. However, there is still room for improvement in overall performance. The main challenge for the commercialization of this technology is the stability of the solar cells under operational conditions. Inorganic perovskite CsPbI3 has attracted researchers’ interest due to its stability at elevated temperatures, however, inorganic perovskites also have associated challenges, e.g. phase stability, larger voltage loss compared to their organic-inorganic hybrid counterparts, and interface energy misalignment. The most efficient inorganic perovskite solar cell is stable for up to a few hundred hours while the most stable device in the field of inorganic PSCs reported so far is at 17% PCE. This suggests the need for improvement of the interfaces for enhanced open circuit voltage (VOC), and optimization of the energy alignment at the interfaces. This dissertation presents the study on interfaces between the perovskite layer and hole transport layer (HTL) for stable CsPbI3 solar cells.
The first part of the thesis presents an investigation of the CsPbI3 film annealing environment and its subsequent effects on the perovskite/HTL interface dynamics. Thin films annealed in dry air were compared with thin films annealed in ambient air. Synchrotron-based hard X-ray spectroscopy (HAXPES) measurements reveal that annealing in ambient air does not have an adverse effect; instead, those samples undergo surface band bending. This surface band modification induces changes in interface charge dynamics and, consequently, an improvement in charge extraction at the interfaces. Further, transient surface photovoltage (tr-SPV) simulations show that air-annealed samples exhibit fewer trap states compared to samples annealed in dry air. Finally, by annealing the CsPbI3 films in ambient air, a PCE of 19.8% and Voc of 1.23 V were achieved for an n-i-p structured device.
Interface engineering has emerged as a strategy to extract the charge and optimize the energy alignment in perovskite solar cells (PSCs). An interface with fewer trap states and energy band levels closer to the selective contact helps to attain improved efficiencies in PSCs. The second part of the thesis presents a design for the CsPbI3/HTM interface. In this work, an interface between CsPbI3 perovskite and its hole selective contact N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl)-9,9′-spirobi[9H-fluorene]-2,2′,7,7′-tetramine(Spiro-OMeTAD), realized by trioctylphosphine oxide (TOPO), a dipole molecule is introduced. On top of a perovskite film well-passivated by n-octyl ammonium Iodide (OAI), it created an upward surface band-bending at the interface byTOPO that optimizes energy level alignment and enhances the extraction of holes from the perovskite layer to the hole transport material. Consequently, a Voc of 1.2 V and high-power conversion efficiency (PCE) of over 19% were achieved for inorganic CsPbI3 perovskite solar cells. In addition, the work also sheds light on the interfacial charge-selectivity and the long-term stability of CsPbI3 perovskite solar cells.
The third part of the thesis extends the previous studies to polymeric poly(3-hexylthiophene-2,5-diyl) (P3HT) as HTL. The CsPbI3/P3HT interface is critical due to high non-radiative recombination. This work presents a CsPbI3/P3HT interface modified with a long-chain alkyl halide molecule, n-hexyl trimethyl ammonium bromide (HTAB). This molecule largely passivates the CsPbI3 perovskite surface and improves the charge extraction across the interface. Consequently, a Voc of over 1.00 V and 14.2% PCE were achieved for CsPbI3 with P3HT as HTM.
Overall the results presented in this dissertation introduce and discuss methods to design and study the interfaces in CsPbI3-based solar cells. This study can pave the way for novel interface designs between CsPbI3 and HTM for charge extraction, efficiency and stability.
The kinetics of water transfer between the lower critical solution temperature (LCST) and upper critical solution temperature (UCST) thermoresponsive blocks in about 10 nm thin films of a diblock copolymer is monitored by in situ neutron reflectivity. The UCST-exhibiting block in the copolymer consists of the zwitterionic poly(4((3-methacrylamidopropyl)dimethylammonio)butane-1-sulfonate), abbreviated as PSBP. The LCST-exhibiting block consists of the nonionic poly(N-isopropylacrylamide), abbreviated as PNIPAM. The as-prepared PSBP80-b-PNIPAM(400) films feature a three-layer structure, i.e., PNIPAM, mixed PNIPAM and PSBP, and PSBP. Both blocks have similar transition temperatures (TTs), namely around 32 degrees C for PNIPAM, and around 35 degrees C for PSBP, and with a two-step heating protocol (20 degrees C to 40 degrees C and 40 degrees C to 80 degrees C), both TTs are passed. The response to such a thermal stimulus turns out to be complex. Besides a three-step process (shrinkage, rearrangement, and reswelling), a continuous transfer of D2O from the PNIPAM to the PSBP block is observed. Due to the existence of both, LCST and UCST blocks in the PSBP80-b-PNIPAM(400 )film, the water transfer from the contracting PNIPAM, and mixed layers to the expanding PSBP layer occurs. Thus, the hydration kinetics and thermal response differ markedly from a thermoresponsive polymer film with a single LCST transition.
Fabricating electronic devices from natural, renewable resources has been a common goal in engineering and materials science for many years. In this regard, carbon is of special significance due to its biological compatibility. In the laboratory, carbonized materials and their composites have been proven as promising solutions for a range of future applications in electronics, optoelectronics, or catalytic systems. On the industrial scale, however, their application is inhibited by tedious and expensive preparation processes and a lack of control over the processing and material parameters. Therefore, we are exploring new concepts for the direct utilization of functional carbonized materials in electronic applications. In particular, laser-induced carbonization (carbon laser-patterning (CLaP)) is emerging as a new tool for the precise and selective synthesis of functional carbon-based materials for flexible on-chip applications.
We developed an integrated approach for on-the-spot laser-induced synthesis of flexible, carbonized films with specific functionalities. To this end, we design versatile precursor inks made from naturally abundant starting compounds and reactants to cast films which are carbonized with an infrared laser to obtain functional patterns of conductive porous carbon networks. In our studies we obtained deep mechanistic insights into the formation process and the microstructure of laser-patterned carbons (LP-C). We shed light on the kinetic reaction mechanism based on the interplay between the precursor properties and the reaction conditions. Furthermore, we investigated the use of porogens, additives, and reactants to provide a toolbox for the chemical and physical fine-tuning of the electronic and surface properties and the targeted integration of functional sites into the carbon network. Based on this knowledge, we developed prototype resistive chemical and mechanical sensors. In further studies, we show the applicability of LP-C as electrode materials in electrocatalytic and charge-storage applications.
To put our findings into a common perspective, our results are embedded into the context of general carbonization strategies, fundamentals of laser-induced materials processing, and a broad literature review on state-of-the-art laser-carbonization, in the general part.
This habilitation thesis summarises the research work performed by the author during the last quindecennial period. The dissertation reflects his main research interests, which revolve around quantum dynamics of small-sized molecular systems, including their interactions with electromagnetic radiation or dissipative environments. This covers various dynamical processes that involve bound-bound, bound-free, and free-free molecular transitions. The latter encompass light-triggered rovibrational or rovibronic dynamics in bound molecules, molecular photodissociation induced by weak or strong laser fields, state-to-state reactive and/or inelastic molecular collisions, and phonon-driven vibrational relaxation of adsorbates at solid surfaces. Although the dissertation covers different topics of molecular reaction dynamics, most of these studies focus on nuclear quantum effects and their manifestations in experimental measures. The latter are assessed through comparison between quantum and classical predictions, and/or direct confrontation of theory and experiment. Most well known quantum concepts and effects will be encountered in this work. Yet, almost all these quantum notions find their roots in the central pillar of quantum theory, namely, the quantum superposition principle. Indeed, quantum coherence is the main source of most quantum effects, including interference, entanglement, and even tunneling. Thus, the common and predominant theme of all the investigations of this thesis is quantum coherence, and the survival or quenching of subsequent interference effects in various molecular processes. The lion's share of the dissertation is devoted to two associated quantum concepts, which are usually overlooked in computational molecular dynamics, viz. the Berry phase and identical nuclei symmetry. The importance of the latter in dynamical molecular processes and their direct fingerprints in experimental observables also rely very much on quantum coherence and entanglement. All these quantum phenomena are thoroughly discussed within the four main topics that form the core of this thesis. Each topic is described in a separate chapter, where it is briefly summarised and then illustrated with three peer-reviewed publications. The first topic deals with the relevance of quantum coherence/interference in molecular collisions, with a focus on the hydrogen-exchange reaction, H+H2 --> H2+H, and its isotopologues. For these collision processes, the significance of interference of probability amplitudes arises because of the existence of two main scattering pathways. The latter could be inelastic and reactive scattering, direct and time-delayed scattering, or two encircling reaction paths that loop in opposite senses around a conical intersection (CI) of the H3 molecular system. Our joint theoretical-experimental investigations of these processes reveal strong interference and geometric phase (GP) effects in state-to-state reaction probabilities and differential cross sections. However, these coherent effects completely cancel in integral cross sections and reaction rate constants, due to efficient dephasing of interference between the different scattering amplitudes. As byproducts of these studies, we highlight the discovery of two novel scattering mechanisms, which contradict conventional textbook pictures of molecular reaction dynamics. The second topic concerns the effect of the Berry phase on molecular photodynamics at conical intersections. To understand this effect, we developed a topological approach that separates the total molecular wavefunction of an unbound molecular system into two components, which wind in opposite senses around the conical intersection. This separation reveals that the only effect of the geometric phase is to change the sign of the relative phase of these two components. This in turn leads to a shift in the interference pattern of the molecular system---a phase shift that is reminiscient of the celebrated Aharonov-Bohm effect. This procedure is numerically illustrated with photodynamics at model standard CIs, as well as strong-field dissociation of diatomics at light-induced conical intersections (LICIs). Besides the fundamental aspect of these studies, their findings allow to interpret and predict the effect of the GP on the state-resolved or angle-resolved spectra of pump-probe experimental schemes, particularly the distributions of photofragments in molecular photodissociation experiments. The third topic pertains to the role of the indistinguishability of identical nuclei in molecular reaction dynamics, with an emphasis on dynamical localization in highly symmetric molecules. The main object of these studies is whether nuclear-spin statistics allow dynamical localization of the electronic, vibrational, or even rotational density on a specific molecular substructure or configuration rather than on another one which is identical (indistinguishable). Group-theoretic analysis of the symmetrized molecular wavefunctions of these systems shows that nuclear permutation symmetry engenders quantum entanglement between the eigenstates of the different molecular degrees of freedom. This subsequently leads to complete quenching of dynamical localization over indistinguishable molecular substructures---an observation that is in sharp contradiction with well known textbook views of iconic molecular processes. This is illustrated with various examples of quantum dynamics in symmetric double-well achiral molecules, such as the prototypical umbrella inversion motion of ammonia, electronic Kekulé dynamics in the benzene molecule, and coupled electron-nuclear dynamics in laser-induced indirect photodissociation of the dihydrogen molecular cation. The last part of the thesis is devoted to the development of approximate wavefunction approaches for phonon-induced vibrational relaxation of adsorbates (system) at surfaces (bath). Due to the so-called 'curse of dimensionality', these system-bath complexes cannot be handled with standard wavefunction methods. To alleviate the exponential scaling of the latter, we developed approximate yet quite accurate numerical schemes that have a polynomial scaling with respect to the bath dimensionality. The corresponding algorithms combine symmetry-based reductions of the full vibrational Hilbert space and iterative Krylov techniques. These approximate wavefunction approaches resemble the 'Bixon-Jortner model' and the more general 'quantum tier model'. This is illustrated with the decay of H-Si (D-Si) vibrations on a fully H(D)-covered silicon surface, which is modelled with a phonon-bath of more than two thousand oscillators. These approximate methods allow reliable estimation of the adsorbate vibrational lifetimes, and provide some insight into vibration-phonon couplings at solid surfaces. Although this topic is mainly computational, the developed wavefunction approaches permit to describe quantum entanglement between the system and bath states, and to embody some coherent effects in the time-evolution of the (sub-)system, which cannot be accounted for with the widely used 'reduced density matrix formalism'.
Functional materials, also called "Smart Materials", are described by their ability to fulfill a desired task through targeted interaction with its environment. Due to this functional integration, such materials are of increased interest, especially in areas where the increasing micronization of components is required. Modern manufacturing processes (e.g. microfluidics) and the availability of a wide variety of functional materials (e.g. shape memory materials) now enable the production of particle-based switching components. This category includes micropumps and microvalves, whose basic function is the active control of liquid flows. One approach in realizing those microcomponents as pursued by this work, enables variable size-switching of water-filled microballoons by implementing a stimulus-sensitive switching motif in the capsule's membrane shell, while being under the influence of a constant driving force. The switching motif with its gatekeeper function has a critical influence on one or more material parameters, which modulate the capsule's resistance against the driving force in microballoon expansion process. The advantage of this concept is that even non-variable analyte conditions, such as concentration levels of ions, can be capitalized to generate external force fields that, under the control of the membrane, cause an inflation of the microballoon by an osmotically driven water influx. In case of osmotic pressure gradients as the driving force for the capsule expansion, material parameters associated with the gatekeeper function are specifically the permeability and the mechanical stiffness of the shell material. While a modulation of the shell permeability could be utilized to kinetically impede the water influx on large time scales, a modulation of the shell's mechanical stiffness even might be utilized to completely prevent the capsule inflation due to a possible non-deformability beneath a certain threshold pressure. In polymer networks, which are a suitable material class for the demanded capsule shell because of their excellent elasticity, both the permeability and the mechanical properties are strongly influenced by the crystallinity of the material. Since the permeability is effectively reduced with increasing crystallinity, while the mechanical stiffness is simultaneously greatly increased, both effects point in the same direction in terms of their functional relationship. For this reason and due to a reversible and contactless modulation of the membrane crystallinity by heat input, crystallites may be suitable switching motifs for controlling the capsule expansion. As second design element of reversible expandable microballoons, the capsule geometry, defined by an aqueous core enveloped by the temperature-sensitive polymer network membrane, should allow an osmotic pressure gradient across the membrane layer. The strength of the inflation pressure and the associated inflation velocity upon membrane melting should be controlled by the salt concentration within the aqueous core, while a turn in the osmotic gradient should furthermore allow the reversible process of capsule deflation. Therefore, it should be possible to build either microvalves and micropumps, while their intended action of either pumping or valving is determined by their state of expansion and the direction of the osmotic pressure gradient.. Microballoons of approximately 300 µm in diameter were formed via droplet-based microfluidics from double-emulsion templates (w/o/w). The elastomeric capsule membrane was formed by photo-crosslinking of methacrylate (MA) functionalized oligo(ε-caprolactone) precursors (≈ 3.8 MA-arms, Mn ≈ 12000 g mol-1) within the organic medium layer (o) via UV-exposure after droplet-formation. After removal of the toluene/chloroform mixture by slow extraction via the continuous aqueous phase, the capsules solidified under the development of a characteristic "mushroom"-like shape at specific experimental conditions (e.g. λ = 308 nm, 57 mJ·s-1·cm-2, 16 min). It could be furthermore shown that in dependency to the process parameters: oligomer concentration and curing-time also spherical capsules were accessible. Long curing-times and high oligomer concentrations at a fixed light-intensity favored the formation of "mushroom"-like capsules, whereas the contrary led to spherical shaped capsules. A comparative study on thin polymer network films of same composition and equal treatment proved a correlation between the film's crosslink density and their contraction capability, while stronger crosslinked polymer networks showed a stronger contraction after solvent removal. In combination with observations during capsule solidification via light-microscopy, where a continuous shaping from almost spherical crosslinked templates to "mushroom"-shaped and solidified capsules was stated, the following mechanism was proposed. In case of low oligomer contents and short curing-times, the contraction of the capsule shell during solvent removal is strongly diminished due to a low degree of crosslinking. Therefore, the solidifying shell could freely collapse onto the aqueous core. In the other case, high oligomer concentrations and long curing-times will favor the formation of highly crosslinked capsule membranes with a strong contraction capability. Due to an observed decentered location of the aqueous core within the swollen polymer network, an uneven radial stress along the capsule's circumference is exerted to the incompressible core. This lead to an uneven contraction during solvent removal and a directed flow of the core fluid into the direction of the minimal stress vector. In consequence, the initially thicker spherical cap contracts, whereas the opposing thinner spherical cap get stretched. The "mushroom"-shape over some advantages over their spherical shaped counterparts, why they were selected for the further experiments. Besides the necessity of a high density of crosslinking for the purpose of extraordinary elasticity and toughness, the form-anisotropy promotes a faster microballoon expandability due to a partial reduction of the membrane thickness. Additionally, pre-stretched regions of thin thickness might provide a better resistance against inflation pressure than spherical but non-stretched capsules of equal membrane thickness. The resulting "mushroom"-shaped microcapsules exhibited a melting point of Tm ≈ 50 - 60 °C and a degree of crystallinity of Xc ≈ 29 - 38 % depending on the membrane thickness and internal salt content, which is slightly lower than for the non-crosslinked oligomer and reasoned by a limited chain mobility upon crosslinking. Nonetheless, the melting transition of the polymer network was associated with a strong drop in its mechanical stiffness, which was shown to have a strong influence on the osmotic driven expansion of the microcapsules. Capsules that were subjected to osmotic pressures between 1.5 and 4.7 MPa did not expand if the temperature was well below the melting point of the capsule's membrane, i.e. at room temperature. In contrast, a continuous expansion, while approaching asymptotically to a final capsule size, was observed if the temperature exceeded the melting point, i.e. 60 °C. Microballoons, which were kept for 56 days at ∆Π = 1.5 MPa and room temperature, did not change significantly in diameter, why the impact of the mechanical stiffness on the expansion behavior is considered to be the greater than the influence of the shell permeability. The time-resolved expansion behavior of the microballoons above their Tm was subsequently modeled, using difusion equations that were corrected for shape anisotropy and elastic restoring forces. A shape-related and expansion dependent pre-factor was used to dynamically address the influence of the shell thickness differences along the circumference on the inflation velocity, whereas the microballoon's elastic contraction upon inflation was rendered by the inclusion of a hyperelastic constitutive model. An important finding resulting from this model was the pronounced increase in inflation velocity compared to hypothetical capsules with a homogeneous shell thickness, which stresses the benefit of employing shape anisotropic balloon-like capsules in this study. Furthermore, the model was able to predict the finite expandability on basis of entropy-elastic recovery forces and strain-hardening effects. A comparison of six different microballoons with different shell thicknesses and internal salt contents showed the linear relationship between the volumetric expansion, the shell thickness and the applied osmotic pressure, as represented by the model. As the proposed model facilitates the prediction of the expansion kinetics depending on the membranes mechanical and diffusional characteristics, it might be a screening tool for future material selections. In course of the microballoon expansion process, capsules of intermediate diameters could be isolated by recrystallization of the membrane, which is mainly caused by a restoration of the membrane's mechanical stiffness and is otherwise difficult to achieve with other stimuli-sensitive systems. The capsule's crystallinity of intermediate expansion states was nearly unchanged, whereas the lamellar crystal size tends to decreased with the expansion ratio. Therefore, it was assumed that the elastic modulus was only minimally altered and might increased due to the networks segment-chain extension. In addition to the volume increase achieved by inflation, a turn in the osmotic gradient also facilitated the reversible deflation, which was shown in inflation/deflation cycles. These both characteristics of the introduced microballoons are important parameter regarding the realization of micropumps and microvalves. The fixation of expanded microcapsules via recrystallization enabled the storage of entropy-elastic strain-energy, which could be utilized for pumping actions in non-aqueous media. Here, the pumping velocity depended on both, the type of surrounding medium and the applied temperature. Surrounding media that supported the fast transport of pumped liquid showed an accelerated deflation, while high temperatures further accelerate the pumping velocity. Very fast rejection of the incorporated payload was furthermore realized with pierced expanded microballoons, which were subjected to temperatures above their Tm. The possible fixation of intermediate particle sizes provide opportunities for vent constructions that allowed the precise adjustment of specific flow-rates and multiple valve openings and closings. A valve construction was realized by the insertion of a single or multiple microballoons in a microfluidic channel. A complete and a partial closing of the microballoon-valves was demonstrated as a function of the heating period. In this context, a difference between the inflation and deflation velocity was stated, summarizing slower expansion kinetics. Overall, microballoons, which presented both on-demand pumping and reversible valving by a temperature-triggered change in the capsule's volume, might be suitable components that help to design fully integrated LOC devices, due to the implementation of the control switch and controllable inflation/deflation kinetics. In comparison to other state of the art stimuli-sensitive materials, one has to highlight the microballoons capability of stabilizing almost continuously intermediate capsule sizes by simple recrystallization of the microballoon's membrane.
Complex emulsions are dispersions of kinetically stabilized multiphasic emulsion droplets comprised of two or more immiscible liquids that provide a novel material platform for the generation of active and dynamic soft materials. In recent years, the intrinsic reconfigurable morphological behavior of complex emulsions, which can be attributed to the unique force equilibrium between the interfacial tensions acting at the various interfaces, has become of fundamental and applied interest. As such, particularly biphasic Janus droplets have been investigated as structural templates for the generation of anisotropic precision objects, dynamic optical elements or as transducers and signal amplifiers in chemo- and bio-sensing applications. In the present thesis, switchable internal morphological responses of complex droplets triggered by stimuli-induced alterations of the balance of interfacial tensions have been explored as a universal building block for the design of multiresponsive, active, and adaptive liquid colloidal systems. A series of underlying principles and mechanisms that influence the equilibrium of interfacial tensions have been uncovered, which allowed the targeted design of emulsion bodies that can alter their shape, bind and roll on surfaces, or change their geometrical shape in response to chemical stimuli. Consequently, combinations of the unique triggerable behavior of Janus droplets with designer surfactants, such as a stimuli-responsive photosurfactant (AzoTAB) resulted for instance in shape-changing soft colloids that exhibited a jellyfish inspired buoyant motion behavior, holding great promise for the design of biological inspired active material architectures and transformable soft robotics.
In situ observations of spherical Janus emulsion droplets using a customized side-view microscopic imaging setup with accompanying pendant dropt measurements disclosed the sensitivity regime of the unique chemical-morphological coupling inside complex emulsions and enabled the recording of calibration curves for the extraction of critical parameters of surfactant effectiveness. The deduced new "responsive drop" method permitted a convenient and cost-efficient quantification and comparison of the critical micelle concentrations (CMCs) and effectiveness of various cationic, anionic, and nonionic surfactants. Moreover, the method allowed insightful characterization of stimuli-responsive surfactants and monitoring of the impact of inorganic salts on the CMC and surfactant effectiveness of ionic and nonionic surfactants. Droplet functionalization with synthetic crown ether surfactants yielded a synthetically minimal material platform capable of autonomous and reversible adaptation to its chemical environment through different supramolecular host-guest recognition events. Addition of metal or ammonium salts resulted in the uptake of the resulting hydrophobic complexes to the hydrocarbon hemisphere, whereas addition of hydrophilic ammonium compounds such as amino acids or polypeptides resulted in supramolecular assemblies at the hydrocarbon-water interface of the droplets. The multiresponsive material platform enabled interfacial complexation and
thus triggered responses of the droplets to a variety of chemical triggers including metal ions, ammonium compounds, amino acids, antibodies, carbohydrates as well as amino-functionalized solid surfaces.
In the final chapter, the first documented optical logic gates and combinatorial logic circuits based on complex emulsions are presented. More specifically, the unique reconfigurable and multiresponsive properties of complex emulsions were exploited to realize droplet-based logic gates of varying complexity using different stimuli-responsive surfactants in combination with diverse readout methods. In summary, different designs for multiresponsive, active, and adaptive liquid colloidal systems were presented and investigated, enabling the design of novel transformative chemo-intelligent soft material platforms.
A new solid-state material, N-butyl pyridinium diiodido argentate(I), is synthesized using a simple and effective one-pot approach. In the solid state, the compound exhibits 1D ([AgI2](-))(n) chains that are stabilized by the N-butyl pyridinium cation. The 1D structure is further manifested by the formation of long, needle-like crystals, as revealed from electron microscopy. As the general composition is derived from metal halide-based ionic liquids, the compound has a low melting point of 100-101 degrees C, as confirmed by differential scanning calorimetry. Most importantly, the compound has a conductivity of 10(-6) S cm(-1) at room temperature. At higher temperatures the conductivity increases and reaches to 10(-4 )S cm(-1) at 70 degrees C. In contrast to AgI, however, the current material has a highly anisotropic 1D arrangement of the ionic domains. This provides direct and tuneable access to fast and anisotropic ionic conduction. The material is thus a significant step forward beyond current ion conductors and a highly promising prototype for the rational design of highly conductive ionic solid-state conductors for battery or solar cell applications.
A new solid-state material, N-butyl pyridinium diiodido argentate(I), is synthesized using a simple and effective one-pot approach. In the solid state, the compound exhibits 1D ([AgI2](-))(n) chains that are stabilized by the N-butyl pyridinium cation. The 1D structure is further manifested by the formation of long, needle-like crystals, as revealed from electron microscopy. As the general composition is derived from metal halide-based ionic liquids, the compound has a low melting point of 100-101 degrees C, as confirmed by differential scanning calorimetry. Most importantly, the compound has a conductivity of 10(-6) S cm(-1) at room temperature. At higher temperatures the conductivity increases and reaches to 10(-4 )S cm(-1) at 70 degrees C. In contrast to AgI, however, the current material has a highly anisotropic 1D arrangement of the ionic domains. This provides direct and tuneable access to fast and anisotropic ionic conduction. The material is thus a significant step forward beyond current ion conductors and a highly promising prototype for the rational design of highly conductive ionic solid-state conductors for battery or solar cell applications.