Glycol bearing perylene monoimide based non-fullerene acceptors with increased dielectric permittivity.

Unlabelled: Perylene monoimide based electron acceptors have great properties for use in organic solar cells, like thermal stability, strong absorption, and simple synthesis. However, they typically exhibit low values for the dielectric permittivity. This hinders efficient exciton dissociation, limiting the achievable power conversion efficiencies.

Silicon- and Germanium-Functionalized Perylene Diimides: Synthesis, Optoelectronic Properties, and Their Application as Non-fullerene Acceptors in Organic Solar Cells.

Organic solar cells have been continuously studied and developed through the last decades. A major step in their development was the introduction of fused-ring non-fullerene electron acceptors. Yet, beside their high efficiency, they suffer from complex synthesis and stability issues.

Bio-Polyester/Rubber Compounds: Fabrication, Characterization, and Biodegradation.

Biobased and biodegradable polymers (BBDs) such as poly(3-hydroxy-butyrate), PHB, and poly(3-hydroxybutyrate--3-hydroxyvalerate) (PHBV) are considered attractive alternatives to fossil-based plastic materials since they are more environmentally friendly. One major problem with these compounds is their high crystallinity and brittleness. In order to generate softer materials without using fossil-based plasticizers, the suitability of natural rubber (NR) as an impact modifier was investigated in PHBV blends.

Novel stereoisomeric lignin-derived polycarbonates: towards the creation of bisphenol polycarbonate mimics.

In this work, we have described a family of bio-based polycarbonates (PC-MBC) based on the unique lignin-derived aliphatic diol 4,4'-methylenebiscyclohexanol (MBC) that was sustainably sourced from lignin oxidation mixture. The detailed structure analysis of these polycarbonates has been confirmed by a series of 2D NMR (HSQC and COSY) characterizations. Depending on the stereoisomerism of MBC, the PC-MBC displayed a wide achievable range of 117-174 °C and high of >310 °C by variation of the ratio of the stereoisomers of MBC, offering great substitution perspectives towards a bisphenol-containing polycarbonates.

High-Performance Thermoplastics from a Unique Bicyclic Lignin-Derived Diol.

Polyesters are an important class of thermoplastic polymers, and there is a clear demand to find high-performing, recyclable, and renewable alternatives. In this contribution, we describe a range of fully bio-based polyesters obtained upon the polycondensation of the lignin-derived bicyclic diol 4,4'-methylenebiscyclohexanol (MBC) with various cellulose-derived diesters. Interestingly, the use of MBC in combination with either dimethyl terephthalate (DMTA) or dimethyl furan-2,5-dicarboxylate (DMFD) resulted in polymers with industrially relevant glass transition temperatures in the 103-142 °C range and high decomposition temperatures (261-365 °C range).

Recent Progress in the Design of Fused-Ring Non-Fullerene Acceptors-Relations between Molecular Structure and Optical, Electronic, and Photovoltaic Properties.

Organic solar cells are on the dawn of the next era. The change of focus toward non-fullerene acceptors has introduced an enormous amount of organic n-type materials and has drastically increased the power conversion efficiencies of organic photovoltaics, now exceeding 18%, a value that was believed to be unreachable some years ago. In this Review, we summarize the recent progress in the design of ladder-type fused-ring non-fullerene acceptors in the years 2018-2020.

Wide-bandgap organic solar cells with a novel perylene-based non-fullerene acceptor enabling open-circuit voltages beyond 1.4 V.

A perylene-based acceptor (PMI-FF-PMI), consisting of two perylene monoimide (PMI) units bridged with a dihydroindeno[1,2-]fluorene molecule was developed as a potential non-fullerene acceptor (NFA) for organic solar cells (OSCs). The synthesized NFA was combined with the high-performance donor polymer D18 to fabricate efficient OSCs. With an effective bandgap of 2.

Phenylene-Bridged Perylene Monoimides as Acceptors for Organic Solar Cells: A Study on the Structure-Property Relationship.

A series of non-fullerene acceptors based on perylene monoimides coupled in the peri position through phenylene linkers were synthesized via Suzuki-coupling reactions. Various substitution patterns were investigated using density functional theory (DFT) calculations in combination with experimental data to elucidate the geometry and their optical and electrochemical properties. Further investigations of the bulk properties with grazing incidence wide angle X-ray scattering (GIWAXS) gave insight into the stacking behavior of the acceptor thin films.

Benefits of direct electron detection and PCA for EELS investigation of organic photovoltaics materials.

Electron energy-loss spectroscopy (EELS) is a powerful tool for imaging chemical variations at the nanoscale. Here, we investigate a polymer/organic small molecule-blend used as absorber layer in an organic solar cell and employ EELS for distinguishing polymer donor and small molecule acceptor domains in the nanostructured blend based on elemental maps of light elements, such as nitrogen, sulfur or fluorine. Especially for beam sensitive samples, the electron dose needs to be limited, therefore optimized acquisition and data processing strategies are required.

Synthesis and characterization of zinc di(-2,2-dimethylpentan-3-yl dithiocarbonates) bearing pyridine or tetramethylethylenediamine coligands and investigation of their thermal conversion mechanisms towards nanocrystalline zinc sulfide.

Metal xanthates are versatile single source precursors for the preparation of various metal sulfides. In this study, we present the synthesis of the two novel zinc xanthate complexes bis(O-2,2-dimethylpentan-3-yl-dithiocarbonato)(N,N,N',N'-tetramethylethylenediamine)zinc(ii) and bis(O-2,2-dimethylpentan-3-yl-dithiocarbonato)(pyridine)zinc(ii). A thorough investigation of these compounds revealed distinct differences in their structural and thermal properties.

Synthesis of a tetrazine-quaterthiophene copolymer and its optical, structural and photovoltaic properties.

Herein, we report the synthesis of a novel, tetrazine-based conjugated polymer. Tetrazines have the benefit of being strong electron acceptors, while little steric hindrance is imposed on the flanking thiophene rings. Conversion of a suitably substituted nitrile precursor led to 3,6-bis(5-bromo-4-(2-octyldodecyl)thiophen-2-yl)-1,2,4,5-tetrazine (2OD-TTz).

Multi-layered nanoscale cellulose/CuInS sandwich type thin films.

A generic procedure for the manufacturing of cellulose-metal sulfide multilayered sandwich type thin films is demonstrated at the example of copper indium sulfide. These multilayers were created by alternate spin coating steps of precursors, followed by their conversion using either acidic vapors, or heat treatment. As precursors, cellulose xanthate, a widely available cellulose derivative employed in viscose fiber manufacturing and commercial copper and indium xanthates were used.

A Zero-Dimensional Mixed-Anion Hybrid Halogenobismuthate(III) Semiconductor: Structural, Optical, and Photovoltaic Properties.

In this contribution, we present the synthesis and characterization of the mixed-anion halogenobismuthate(III) (CHNH)BiICl (MBIC) as an alternative lead-free perovskite-type semiconductor, and discuss its optical, electronic, and photovoltaic properties in comparison to the methylammonium bismuth iodide (CHNH)BiI (MBI) compound. The exchange of iodide with chloride during synthesis leads to the formation of an orthorhombic ABX-type crystal structure ( Cmma, No. 67) with isolated BiX octahedra and methylammonium chloride interlayers.

Reverse Hexosome Dispersions in Alkanes-The Challenge of Inverting Structures.

Monoglycerides form lipophilic liquid-crystalline (LC) phases when mixed with water. The corresponding LC nanostructures coexist with excess water, which is a necessary condition for the formation of internally nanostructured dispersed particles. These nanostructures comprise bicontinuous cubic phases, inverted hexagonal phases, and inverted micellar cubic phases.

Progress on lead-free metal halide perovskites for photovoltaic applications: a review.

Abstract: Metal halide perovskites have revolutionized the field of solution-processable photovoltaics. Within just a few years, the power conversion efficiencies of perovskite-based solar cells have been improved significantly to over 20%, which makes them now already comparably efficient to silicon-based photovoltaics. This breakthrough in solution-based photovoltaics, however, has the drawback that these high efficiencies can only be obtained with lead-based perovskites and this will arguably be a substantial hurdle for various applications of perovskite-based photovoltaics and their acceptance in society, even though the amounts of lead in the solar cells are low.

On the formation of BiS-cellulose nanocomposite films from bismuth xanthates and trimethylsilyl-cellulose.

The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for BiS and trimethylsilyl cellulose (TMSC) for cellulose. Solutions of these precursors were spin coated onto solid substrates yielding homogeneous precursor films.

Synthesis and characterization of naphthalimide-functionalized polynorbornenes.

Abstract: Highly fluorescent and photostable (2-alkyl)-1-benzo[]isoquinoline-1,3(2)-diones with a polymerizable norbornene scaffold have been synthesized and polymerized using ring-opening metathesis polymerization. The monomers presented herein could be polymerized in a living fashion, using different comonomers and different monomer ratios. All obtained materials showed good film-forming properties and bright fluorescence caused by the incorporated push-pull chromophores.

Adsorption Studies of Organophosphonic Acids on Differently Activated Gold Surfaces.

In this study, the formation of self-assembled monolayers consisting of three organophosphonic acids (vinyl-, octyl-, and tetradecylphosphonic acid) from isopropanol solutions onto differently activated gold surfaces is studied in situ and in real time using multiparameter surface plasmon resonance (MP-SPR). Data retrieved from MP-SPR measurements revealed similar adsorption kinetics for all investigated organophosphonic acids (PA). The layer thickness of the immobilized PA is in the range of 0.

Polymer/Nanocrystal Hybrid Solar Cells: Influence of Molecular Precursor Design on Film Nanomorphology, Charge Generation and Device Performance.

In this work, molecular tuning of metal xanthate precursors is shown to have a marked effect on the heterojunction morphology of hybrid poly(3-hexylthiophene-2,5-diyl) (P3HT)/CdS blends and, as a result, the photochemical processes and overall performance of in situ fabricated hybrid solar cells. A series of cadmium xanthate complexes is synthesized for use as in situ precursors to cadmium sulfide nanoparticles in hybrid P3HT/CdS solar cells. The formation of CdS domains is studied by simultaneous GIWAXS (grazing incidence wide-angle X-ray scattering) and GISAXS (grazing incidence small-angle X-ray scattering), revealing knowledge about crystal growth and the formation of different morphologies observed using TEM (transmission electron microscopy).

Ex situ and in situ characterization of patterned photoreactive thin organic surface layers using friction force microscopy.

Photolithographic methods allow an easy lateral top-down patterning and tuning of surface properties with photoreactive molecules and polymers. Employing friction force microscopy (FFM), we present here different FFM-based methods that enable the characterization of several photoreactive thin organic surface layers. First, three ex situ methods have been evaluated for the identification of irradiated and non-irradiated zones on the same organosilane sample by irradiation through different types of masks.

Nanoimprinted comb structures in a low bandgap polymer: thermal processing and their application in hybrid solar cells.

In this paper, we investigate conjugated polymer layers structured by nanoimprint lithography toward their suitability for the fabrication of nanostructured polymer/metal sulfide hybrid solar cells. Consequently, we first study the thermal stability of the nanoimprinted conjugated polymer layers by means of scanning electron microscopy and grazing incidence small-angle X-ray scattering, which reveals a reasonable thermal stability up to 145 °C and sufficient robustness against the solvent mixture used in the subsequent fabrication process. In the second part, we demonstrate the preparation of nanostructured polymer/copper indium sulfide hybrid solar cells via the infiltration and thermal decomposition of a mixture of copper and indium xanthates.

A combined approach to predict spatial temperature evolution and its consequences during FIB processing of soft matter.

Accessing local temperatures and their evolution during focused ion beam (FIB) processing is of particular importance in the context of polymers or biomaterials as they tend to undergo severe chemical and morphological damage due to the high temperatures arising. In this study we present a combination of ion trajectory simulations and thermal spike model based calculations, which allows predicting local temperatures, lateral distributions and evolution during FIB patterning. Simulations and calculations have been done without any approximation or correction factors and lead to results in very good agreement with experiments on polymers taking into account their thermal behaviour.

Influence of morphology and polymer:nanoparticle ratio on device performance of hybrid solar cells-an approach in experiment and simulation.

We present a thorough study on the various impacts of polymer:nanoparticle ratios on morphology, charge generation and device performance in hybrid solar cells, comprising active layers consisting of a conjugated polymer and in situ prepared copper indium sulfide (CIS) nanoparticles. We conducted morphological studies through transmission electron microscopy and transient absorption measurements to study charge generation in absorber layers with polymer:nanoparticle weight ratios ranging from 1:3 to 1:15. These data are correlated to the characteristic parameters of the prepared solar cells.

Photo-Fries-based photosensitive polymeric interlayers for patterned organic devices.

This work reports on the investigation of the photosensitive polymer poly(diphenyl bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate) (PPNB), which undergoes the photo-Fries rearrangement upon illumination with UV-light, used as interfacial layers in organic electronic devices.