Symposium CF
Advances in Functional Materials for Energy Harvesting, Storage and Solar Fuels


CF-1:IL01  Nano-structured Oxide Sponges; From Precursor to Complex Oxides
G. WESTIN, S.N. Katea, Department of Chemistry-Ångström, Ångström laboratory, Uppsala, Sweden

There is a strong demand for tailored materials for sensors, catalysts, solar-cells and energy storage for renewable energy areas. Typical features of these materials are; a large interface to the surrounding liquid electrolyte, reaction liquid, or gas phase, surface modification for e.g. band structure and corrosion control, and catalysis. Often a high conductivity is required to get generated electrons out to the surface or electrode which implies materials of high crystalline quality with controlled dopant positioning, as well as a good connectivity though the structure. Here we present new salt-based synthesis routes yielding oxide sponges of various contents at down to 200 °C, 3min. Systems such as doped and non-doped ZnO and MgO will be discussed in detail from the solution to the final products, as well as some of their properties. The sponges obtained at 200 °C typically consist of highly porous bread-like structures built up from well-connected, ca 10 nm crystallites. These structures do not sinter together, even on heating to 900 °C, but from ca 500 °C, a reproducible grain growth took place within the sponge structures allowing for tuning of crystal sizes. The processes and products were studied with; TG/DTA/DSC, XRD, IR and Raman spectroscopy, SEM-EDS, TEM-EDS/ED, and XPS

CF-1:IL02  Metal-organic Frameworks-based Biocomposites: Design, Synthesis and Biomedical Applications
P. FALCARO, M. VELASQUEZ-HERNANDEZ, Graz University of Technology, Institute of Physical and Theoretical Chemistry, Graz, Austria

MOFs are a class of hybrid porous materials formed by the self-assembly of metal ions interconnected by multitopic organic linkers. The chemical tunability of this building block approach and their porosity make MOFs suitable candidates for various applications, including gas storage, separation, sensing, and microelectronics. Translating this reticular chemistry approach into applicable technology requires control over the morphology and precise positioning of MOFs onto different platforms. Herein, we discuss our progress in the controlled growth of an oriented Cu-based MOF film by using Cu(OH)2 nanobelts as a Cu2+ source, and directing agent. This strategy can be further extended toward the area-selective deposition of different types of Cu-based MOFs within the same platform. Thus, we demonstrate that the use of pre-shaped ceramic material as sacrificial templates provides control over the orientation, morphology, and spatial location of MOF on substrates.

CF-1:IL04  Nanostructuring and Nanocomposites in Thermoelectric Oxides
F. Giovannelli, C. Chen, F. DELORME, Université de Tours, CNRS, INSA CVL, GREMAN UMR 7347, IUT de Blois, Blois Cedex, France

Thermoelectric materials are able to transform directly heat in electric energy or inversely electric energy in cold. The efficiency of a thermoelectric device depends on the thermoelectric figure of merit ZT that depends on the Seebeck coefficient, the electrical conductivity and the thermal conductivity. However, these three main parameters are strongly interconnected. As a result, improvements achieved on one parameter have usually negative impacts on the others. To overcome this limit, some authors have proposed nanostructuring and/or composite materials in order to optimize the thermoelectric properties: some models predict for composite materials an increase of the power factor, whereas other models indicate that the main effect will be related to a decrease of the thermal conductivity due to phonon scattering by interfaces. For nanostructuring the improvement is mainly expected by phonon scattering by interfaces even if some authors reported PF improvement due to low energy charge carriers filtering. Experimental results with different thermoelectric oxides nanostructuring and composites will be presented and will show complex behavior. The origin of such behavior and key parameters will be discussed.

CF-1:IL05  Advances in the Tailored Fabrication of Metal-oxide Nanoarchitectures for Safety, Environmental Applications and Sustainable Technologies
D. BARRECA1, A. Gasparotto2, L. Bigiani2, C. Maccato2, 1CNR-ICMATE and INSTM, Department of Chemical Sciences, Padova University, Padova, Italy; 2Department of Chemical Sciences, Padova University and INSTM, Padova, Italy

Over the last decades, the rising interest in sustainable energy production, environment and human health safety, has fuelled the fabrication of multi-functional nanomaterials capable to meet the challenges associated to the actual technological requirements. In particular, oxide nanomaterials offer manifold attractive features, whose modification is the Holy Grail to successfully exploit characteristics underpinning applications in the target fields. This talk will present recent advances in innovative processing techniques for nano-and heterostructured functional oxides. Engineering of system properties will be discussed in selected studies for application in: - recognition of toxic analytes at the ppb scale; 1 - sunlight-driven photocatalytic abatement of gaseous pollutants; 2 - H2 generation by solar-activated H2O splitting 3 and from seawarer, 4 and ethanol electrochemical valorization; 5 The obtained results are extremely encouraging and can be a magic spygplass towards further implementation of advanced functional systems and devices.
1 ACS Appl. Mater. Interfaces 2018, 10, 12305; ibid. 2019, 11, 23692 2 RSC Adv. 2016, 6, 74878; Surf. Coat. Technol. 2016, 307, 352 3 Adv. Mater. Interfaces 2015, 2, 1500313 4 Appl. Catal., B 2021, 284, 119684 5 J. Mater. Chem. A 2020, 8, 16902

CF-1:IL06  Nanostructures and Thin Films of Tetragonal Tungsten Bronze Complex Oxides
V. DEMANGE, B. Aspe, A. Waroquet, V. Dorcet, M. Guilloux-Viry, ISCR, France; Q. Simon, GREMAN, Blois, France; B. Gautier, D. Albertini, INL, Lyon, France; R. Sauleau, X. Castel, IETR, Rennes, France

The tetragonal tungsten bronze phases (TTB) are of major interest for the development of new efficient devices on a reduced scale because of their wide range of properties. Ferroelectricity, piezoelectricity, multiferroicity and photocatalytical properties can be achieved by modifying their composition, in addition to their ability to grow as very anisotropic crystals. Present research is focused on thin films of environmental-friendly lead-free oxides in the K-Nb-O (KN), K-Ta-Nb-O (KTN), K-Na-Nb-O (KNN) and (K,Na)-Sr-Ca-Nb-O (KNSCN) systems. Thin films were grown on various substrates and electrodes by pulsed laser deposition which allows the control of both composition and structural properties. The films were grown according to two modes with respect to the substrate surface, i.e. as vertical nanorods with the [001] direction perpendicular to the substrate surface, and as horizontal nanorods with the [001] orientation parallel to the substrate surface and [310] out-of-plane direction. Both vertical and horizontal nanorods present epitaxial relationships with the substrate orientations. Structural, microstructural and dielectric properties will be presented.

CF-1:L10  Carbon Nanotube Coating from Electrophoretic Deposition Designed for Photo thermal Solar Receptors
F. DIDIER, X. Deschanels, G. Toquer, ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France

Efficient photo-thermal solar collectors are growing in importance to limit the use of fossil fuels. For the conception of tandem absorber, different carbon nanotubes, with highly UV-Vis-NIR absorbing, are deposited onto a highly IR reflecting metalized substrate by electrophoretic deposition. In order to guarantee an eco-friendly process, the nanotubes are dispersed in an aqueous solution by purple pyrocatechol. This molecule confers an electric charge to the colloids, while ensuring an electrostatic repulsion. Then, the zeta potential of the colloids is determined to evaluate the stability of the suspensions. The optimal formulation shows no settling for several days. Tandem absorber are obtained by varying different EPD parameters (deposition time, applied potential, inter-electrode distance) in order to control the final thickness, density, morphology of the film and so to tune the absorbance and the reflectance of the tandem absorber. To improve the performance and durability of the deposits, post treatments such as the addition of an antireflective layer or annealing are performed. It is possible to convert more than 90% of the absorbed light into heat, limit the thermal losses (<10%) and guarantee a mechanical stability of the coatings up to 350°C.

CF-1:L12  Novel MOCVD Deposition Strategies to Obtain Thin Films with Improved Functional Properties
M. BURRIEL1, R. Rodriguez-Lamas1, A. Stangl1, A. Riaz1, 3, C. Pirovano2, L. Rapenne1, E. Sarigiannidou1, D. Pla1, O. Chaix-Pluchery1, M. Mermoux3, R.-N. Vannier2, C. Jiménez1, 1Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France; 2Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, Lille, France; 3Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, Grenoble, France

Ionic transport is of primary importance for the development and miniaturization of numerous devices such as solid oxide fuel cells and electrolyzers, oxygen separation membranes, and memristive devices. When prepared in the form of thin films, the functional properties can largely vary in comparison to the intrinsic bulk ones. There is thus a large interest in understanding and controlling the influence of parameters such as epitaxy, substrate-induced strain, and nano-structure, for the use of ionic conducting oxides in applied functional devices. Using Pulsed-Injection Metalorganic Chemical Vapor Deposition we have developed different strategies to control the growth of perovksite, and perovskite-related thin films, such as LaMnO3±δ and La2NiO4+δ. The oxygen stoichiometry, oxygen diffusion, and both the intrinsic and apparent oxygen exchange activity can be tailored in these thin films by tuning the deposition parameters, leading to differences in the amount of point and extended defects in the films, to different strain states, as well as to diverse controlled nano-architectures (dense, nano-columnar, nano-hierarchical). Ultimately by selecting the appropriate deposition conditions a substantial enhancement of the ionic transport properties in the films is achieved.

CF-1:IL14  Advanced Fluoride Films for Energy Conversion
A.L. Pellegrino1, A. Speghini2, G. Malandrino1, 1Dipartimento di Scienze Chimiche, Università di Catania and INSTM UdR Catania, Catania, Italy; 2Nanomaterials Research Group, Dipartimento di Biotecnologie, Università di Verona and INSTM, UdR Verona, Verona, Italy

Fluoride materials have attracted great attention due to a wide variety of applications in dielectrics, optics, optoelectronics and photonics. Recent years have witnessed a pronounced increase of research activities on the synthesis of fluoride thin films also in view of their applications to enhance the efficiency of photovoltaic (PV) devices. To this aim, one promising strategy is to collect the radiation energy outside the absorption range of the photoactive material (usually silicon) through down-conversion (DC) or up-conversion (UC) processes. In particular, the most efficient hosts for energy up-conversion consist of alkaline earth fluoride matrices, as CaF2 and SrF2 and multicomponent NaYF4 phase. In the presentation, an overview will be given on recent results on the fabrication of Ln-doped fluoride thin films through two different chemical routes: Metal-Organic Chemical Vapor Deposition (MOCVD) and sol-gel/spin-coating approaches. Pros and cons of the two synthetic strategies will be discussed in regard to the synthesis of up-converting layers of the type CaF2: Yb/Er, CaF2: Yb/Tm, β-NaYF4: Yb /Er and β-NaYF4: Yb/Tm. Both synthetic approaches use fluorinated metalorganic β-diketonate compounds, which act as single-sources, and have the advantage of being very reliable and reproducible methods for the fast production of films with high uniformity degree over large areas.

CF-1:IL15  2D Molybdenum Dichalcogenides Prepared by Atomic Layer Deposition
R. Zazpe1, 2, J. Charvot3, L. Hromadko1, 2, H. Sopha1, 2, F. Bureš3, J.M. Macak2, 1Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic; 2Central European Institute of Technology, Brno University of Technology, Brno, Czech Republic; 3Institute of Organic Chemistry and Technology, Faculty of Chemical Technology,University of Pardubice, Pardubice, Czech Republic

The success of graphene opened a door for a new class of chalcogenide materials – transition metal dichalcogenides (TMDCs) - with unique properties that can be applied in various applications. In principle, TMDCs can be prepared by various top-down (e.g. exfoliation) and bottom-up techniques, such as chemical vapour deposition (CVD) and atomic layer deposition (ALD) growth techniques. MoS2, a typical TMDCs representative, has been widely studied for many applications. Recently, the possibility to employ ALD as a technique to grow MoS2 has been reported. From the practical point of view, MoSe2 and MoTe2 are even more interesting than MoS2 as they possess a higher electrical conductivity. Recently, we have shown that ALD deposition of MoSe2 and MoTe2 is feasible, using newly developed Se and Te precursor and the MoCl5, respectively, as the Mo precursor. The presentation will focus on the synthesis of MoS2, MoSe2 and MoTe2 by ALD, their characterization and applications in various energy fields. Experimental details and some recent photocatalytic and hydrogen evolution results will be presented and discussed [1-7].
[1] FlatChem 21 (2020) 100166; [2] ACS Appl. Nano Mater. 3 (2021) 12034; [3] Appl. Mater. Today 23 (2021) 101017; [4] Nanoscale 11 (2019) 23126; [5] FlatChem 17 (2019) 10013

CF-1:IL16  Lithium Niobate Thin Films for Vibrational Harvesting
S.MARGUERON, G. Clementi, M. Ouhabaz, M. Costanza, B. Dulmet, A. Bartasyte, UBFC UFC ENSMM CNRS, Institut FEMTO-ST, Besançon, France

Lead-free piezoelectric materials are of special concern due to regulation issues (REACH, RoHS). In this talk I will present our work showing that lithium niobate presents a figure of merit as good as lead-based materials counterpart for vibrational energy harvesting. This work resulted in developping a patented transfert method on different substrates. Finally, I will show our last development of autonomous sensors based on vibrational harvesting.

CF-1:IL18  Processable Polymeric Carbon Nitride for Photoelectro-chemical Applications
I. KRIVTSOV, Institute of Electrochemistry, Ulm University, Germany

Polymeric carbon nitrides (PCN) are organic polymers with a great prospect as photo(electro)catalyst for solar-fuels production due to their low cost, facile preparation, outstanding stability, and ability to efficiently drive photocatalytic redox reactions under light irradiation. A number of synthetic approaches for the preparation of PCNs with tuneable properties have been developed. However, until recently the use of PCN in photoelectrochemical (PEC) devices has been significantly hampered by the lack of effective methods for processing of bulk PCN and preparation of stable and binder-free photoelectrodes. Drawing on a recent discovery of ionic PCNs, also known as poly(heptazine imide) (PHI), we have developed a method for the synthesis of PHI nanoparticles that are fully soluble in water and enable facile sol-gel processing, resulting in robust and binder-free PHI photoanodes with unprecedented PEC performance, including effective alcohols reforming under bias-free conditions. The talk will focus on our most recent studies of these materials, including discussion of intriguing effects in PHI photoanodes, such as photodoping and fast charge extraction, that shed light on their superior PEC performance.

CF-1:IL19  Radially-heterostructured III-V Nanowires for Photonics and Photovoltaics
P. PRETE, IMM-CNR, Lecce, Italy; N. Lovergine, Dept. of Engineering for Innovation, University of Salento, Lecce, Italy

Nanowires of III–V compound semiconductors attract significant interest for their potential applications in novel photonic and photovoltaic nanodevices. Radial modulation of the nanowire composition, forming core-shell heterostructures, influences nanodevices design by allowing new degrees of freedom associated with quantum confinement. However, future nanostructures engineering requires strict control over epitaxial self-assembly and understanding of their nano-scale electronic/radiative properties. We report on the MOVPE growth and nano-spectroscopic/structural properties of GaAs-AlGaAs core-shell and core-multishell NWs forming quantum well tubes (QWTs). By using advanced nano-characterization tools, such as low-temperature cathodoluminescence (CL) spectroscopic imaging, along with a multishell growth model, a robust correlation between the emission properties of the nanowires and their size and inner structure at the nanoscale, is - for the first time - demonstrated. The CL mapping of QWT emission intensities along the nanowire axis allowed to directly image nanoscale localization of the confinement emission, supporting the conclusion that the QWT emission is profoundly affected by carrier localization. These results will foster the QWT applications as efficient solar cells.

CF-1:L21  Photocatalytic Self-cleaning Properties of Developed TiO2 Doped Layered Double Hydroxide in Comparison to the Commercially Available Solutions for Application on Mineral Substrates
B. MILJEVIC1, J.M. van der Bergh2, S. Vučetić1, J. Ranogajec1, R. Cerc Korošec3, 1University of Novi Sad, Faculty of Technology, Novi Sad, Serbia; 2Liverpool John Moores University, Built Environment and Sustainable Technologies (BEST) Research Institute, Liverpool, UK; 3University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Slovenia

Due to their lamellar nano-sheet structure, layered double hydroxides (LDH) are known as materials suitable for carrying of certain active, functional molecules. In order to evaluate the dependence of the photocatalytic self-cleaning properties of LDH with intercalated active substances on the synthesis parameters, a series of ZnAl-LDH suspensions were synthesised using a modified low supersaturation co-precipitation method at various pH values. The optimal pH value was found to be 8. The molybdenum doped TiO2 nanocomposite LDH suspension was synthesised at the optimised pH value. Detailed material characterisation studies by means of thermogravimetry (TG), dynamic scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) were performed. The photocatalytic self-cleaning properties of the optimally synthesised TiO2 doped LDH suspension were assessed when applied on stone, brick and glass substrates and after having been illuminated only by using LED visible light and compared to the properties of commercially available self-cleaning solutions for application on mineral substrates.
The authors acknowledge the support from Ministry of Education, Science and Technological Development (Serbia), 451-03-9/2021-14/200134 and EUREKA E!13085.

CF-2:IL01  Solution-based Green Processing of Hybrid Perovskites for Solar Cell Applications
F. Ünlü1, T. Fischer1, A. Kulkarni2, T. Miyasaka2, S. Mathur1, 1Institute of Inorganic Chemistry, University of Cologne, Cologne, Germany; 2Graduate School of Engineering, Toin University of Yokohama, Aoba, Yokohama, Kanagawa, Japan

Lead based metal halide perovskite solar cells have attracted tremendous research attention due to rapid rise in power conversion efficiency (PCE) from merely 3.8% to 24.2%. Such rise in PCE is attributed to exceptional optoelectronic properties such as long diffusion length, low exciton binding energy, ambipolar charge mobility, narrow bandgap. Despite of these advantages, one of the major problems encountered with this new technology, apart from structural and chemical stability, is the toxicity associated with heavy metal lead. Among various metals explored, bismuth (Bi) based perovskite materials possess promising optoelectronic properties including a high absorption coefficient and can be processed from solution using a variety of wet chemical deposition techniques and additives. In our research, we focused on different various bismuth-based perovskite materials having zero dimensional to higher dimensional networks and investigated their optical, morphological and photovoltaic properties. Interestingly, we could observe, that by increasing the bismuth halide network dimensionality, the power conversion efficiency could be improved. This increase in solar cell performance could be achieved by introducing monovalent noble metals such as silver and copper. The incorporation of these monovalent cations lead to 3D networking of Bismuth halides, losing the typical perovskite structure. At last we discuss the future prospects and potential of non-toxic bismuth to replace lead in lead perovskite solar cells.

CF-2:IL03  Novel Photoanodes for Solar Fuels
S. ESLAVA, M. Regue, D. Walsh, J. Zhang, I. Poli, U. Hintermair, P.J. CamerON, Imperial College London, London, UK

Here I present recent developments we have achieved in the preparation of inexpensive photoanodes for solar water splitting: a nanostructured TiO2 with exposed {0 1 0} facets, an α-Fe2O3 self-coated with FeOx electrocatalyst and with an electrodeposited CoFeOx [3], and a novel all-inorganic halide perovskite CsPbBr3. The nanostructured TiO2 photoanodes are prepared using Ti7O4(OEt)20 clusters as a precursor and resulting photoanodes show a unique morphology resembling desert roses, pure anatase phase and high exposure of the very active {0 1 0} facet, achieving remarkable ⁓100% IPCE efficiency at 350 nm wavelength. α-Fe2O3 photoanodes simultaneously coated with FeOx electrocatalyst are prepared using precursors whose morphology and crystallinity is tuned with lactic acid additive, boosting photoanode photocurrents from 0.32 to 1.39 mA cm-2 at 1.23 V (vs. RHE). An extended electrochemical characterisation also shows that the charge transfer to electrolyte at α-Fe2O3 interfaces can be boosted by an extremely thin layer of CoFeOx. Finally, all-inorganic halide perovskite CsPbBr3 photoanodes are prepared using carbon layers as a hole transport layer, achieving photocurrents above 2 mA cm−2 at 1.23 V (vs. RHE).

CF-2:IL06  Boosting of Photo-induced Charge Carrier Dynamics in  Semiconducting Systems
R. SOLARSKA, K. Bienkowski, Centre of New Technologies, University of Warsaw, Warsaw, Poland

High-performance conversion of solar light to different types of energy which might be subsequently released in different ways, remains an unsaturated need for uninterruptedly growing global demand for energy. However, currently the field of renewable energy suffers from lack of an ideal material able to drive conversion of the solar energy with high quality and quantity and being stable enough to provide a long-term productivity. Therefore, multi-directional efforts including a development of new materials and catalysts, incorporation of plasmonic nanostructures or creation of low-level sub-stoichiometry are continuously undertaken and devoted to minimization of the required bias voltage, improvement of light capture or charge transport properties. Our recent achievements regrading use of different polyoxometalates as molecular catalysts and newly designed hybrid junctions of photosystem I (PSI) in solar driven semiconductor architectures, as well as their performance towards photo- induced processes will be presented and discussed in detail. Besides the extensive characterization of the above-mentioned systems, the kinetic assessment of the transient absorption phenomena will be approached. Use of transient absorption spectroscopy to study charge carrier behavior in the assembled systems allows to relate a photoelectrode architecture to the charge carrier’s origin, separation, collection, trapping, lifetime and therefore to the overall system efficiency. Therefore, our approach will focus on investigation of changes in charge carrier dynamics from the sub nanoseconds up to seconds timescales upon introduction of light intensity and voltage variables, to the system. Presentation and comparison of the charge carrier dynamics occurring in bare semiconductors, modified with polyoxometalates as well as based on photosystem I, will be shown as particularly useful in clarifying the observed differences in their photoelectrochemical performance.

CF-2:IL07  Interfacial Properties in Composite Nano-systems for Energy Harvesting
A. VOMIERO, T. AHMED SHIFA, Division of Materials Science, Dept. of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden, and Department of Molecular Sciences and Nanosystems, Venezia Mestre, Italy

Composite nanostructures can be efficiently applied for Sunlight detection and conversion and, more in general, for energy harvesting and generation of solar fuels. In most of the applied systems, nanomaterials can play a critical role in boosting photoconversion efficiency by ameliorating the processes of charge photogeneration, exciton dissociation and charge transport. Critical role in such processes is played by the structure and quality of the interface, which needs to be properly assembled to obtain the desired functionality. Several strategies can be pursued to maximize energy harvesting and storage, including broadening of light absorbance to reduce solar light losses, fastening exciton dissociation and charge injection from the photoactive medium to the charge transporting materials, reducing charge recombination during charge transport and collection at the electrodes. In this lecture, a few examples of application of nanocomposites will be thoroughly discussed, including all-oxide coaxial p-n junction nanowire photodetectors and solar cells, core-shell quantum dot fluorophores for high-efficiency luminescent solar concentrators, composite sulfides for hydrogen generation.

CF-2:L11  Study of Charge Carrier Dynamics in TiO2 Thin Films by Time Resolved Transient Absorption Spectroscopy
Ramsha Khan, H. Ali-Löytty, A. Tukiainen, N.V. Tkachenko, Photonic Compounds and Nanomaterials Group, Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland

TiO2 has been employed in various photocatalytic applications for its efficient performance. However, the main constraint in achieving high efficiency from TiO2 is charge carriers recombination. In this study, we have compared the charge carrier dynamics of 30 nm thin films of TiO2 prepared by atomic layer deposition (ALD), ion beam sputtering (IBS), and spray pyrolysis deposition (SPD). In all the deposition methods, the as-deposited (as-dep.) samples have been heat-treated (HT) at 500 °C. XRD results reveal that as-dep. samples show no defined crystal structure whereas, HT samples show anatase phase of TiO2. Transient absorption study of the samples was done in both transmittance and reflectance mode to analyze the change of refractive index and lifetime of different samples. The photophysical study shows that after HT, all the samples show similar charge carrier dynamics regardless of their different topographical features and texture as observed in AFM and XRD results, respectively. All the HT samples show extended lifetime of charge carriers from pico-second to nano-second (≥ 4ns) time domain. The measured transient absorption spectra show that relaxation dynamics of photocarriers involve electron and hole trap states where longest-lived being the hole trap states.

CF-2:L14  Incorporation of Spark Ablation and Nanoscale 3D Printing for Deriving Nanostructured Layers
I. PANZIC1, A. Jelinek2, F. Radovanović-Perić1, D. Kiener2, V. Mandić1, 1Faculty of Chemical Engineering and Technology, Zagreb, Croatia; 2Department of Materials Physics, Montanuniversität Leoben, Leoben, Austria

Two-photon laser polymerization allows pushing the limit beyond the 100 nm benchmark and still provides a direct technique that allows the development of complex 3D structures with up to nanoscale resolution. Additional postprocessing of the printed structures by means of chemical, thermal, or plasma etching further widens the possibilities to further decrease the resolution of target structures, limited only by the mechanical properties of the polymer resist used for the printing. In addition to laser printing, spark ablation has recently emerged as a novel technique capable of reproducibly preparing nanoparticles with narrow size distribution. In this work, we combined the aforementioned processes. Spark ablation was used to decorate the surface of the 3D printed samples with metal/metal oxide core-shell nanoparticles. Samples were characterized in depth using microscopies (SEM and AFM) and mechanical testing (in situ SEM mechanical testing) before and after the incorporation of the layers in solar cells as electron transport layers.
Acknowledgments: This work has been funded by the projects KK. by ERDF, UIP-2019-04-2367 SLIPPERY SLOPE by CSF and PZS-2019-02-1555 PV-WALL by CSF, ESF.

CF-2:L16  Titania Thin Films, Photocatalytically Efficient Under Visible Light Illumination
B. Žener, L. Matoh, R. Cerc Korošec, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia

The aim of this work was to increase the photocatalytic activity of titania thin films under visible light irradiation by doping them with nitrogen and/or sulfur, while platinum was added to prevent recombination of photo-generated holes and electrons. The thin films were prepared via the particulate sol-gel route from TiCl4 as a precursor. The synthesis was performed in acidic media, which was achieved by the addition of hydrochloric or sulfuric acid. The addition of an acid enabled faster formation of the sol and increased its stability. The organic polymer was also added into the sol, which was then deposited on glass substrates by dip-coating technique. Thin films were additionally thermally treated to promote crystallization. The temperature of crystallization from amorphous state into one of titania crystalline phases was determined with the help of thermoanalytical techniques. The obtained phase and the average crystallite size were determined from XRD patterns. Scanning electron microscopy provided insight into the morphology of the thin films. Their photocatalytic efficiency was determined by measuring the degradation rate of Plasmocorinth B. Results have shown increased photocatalytic efficiency in samples, doped and co-doped with nitrogen, sulfur and platinum.

CF-3:L03  Implementing Ordered Arrays of Zincite Nanoformations into Transport Layers of Perovskite Photovoltaic Devices
v. Mandić, I. Panžić, F. Radovanović-Perić, Faculty of Chemical Engineering and Technology, Zagreb, Croatia; T. Rath, Institute for Chemistry and Technology of Materials, Graz, Austria

Organic perovskites are quite prominent absorbers. Their performance can be further boosted when interfaced between transport layers consisting of nano-featured semiconducting materials. Ordered arrays of zincite nanoformations were prepared for the purpose of rising up the specific surface area and thereof the charge transfer, but nanofeatured zincite arrays in organic perovskite devices show only limited increase of power conversion efficiency due to considerable recombination. Methyl ammonium and formamidinium iodide perovskites show highest power conversion efficiencies in nanofeatured zincite-based devices, but still suffer from hysteresis and degradation. For the case of the photovoltaic devices without methyl ammonium iodide, one can expect better fill factors and lower rate of hysteresis. For this work we prepared ordered arrays of zincite, before spin coating organic perovskite layer without MAI on top, and closing the solar cell. We want to understand the how preparing affects the overall PSC efficiency. We monitored the cell behavior using J/V, EQE, XRD and SEM as the main methods. We can confirm the interfacing of the layers was reliable, facilitating the further development of perovskite photovoltaic devices.
Acknowledgements: This work has been funded by the projects KK. by ERDF, UIP-2019-04-2367 SLIPPERY SLOPE by CSF and PZS-2019-02-1555 PV-WALL by CSF, ESF.


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