Research Unit (FOR) 5301 „FuncHeal“

Principle Investigators

Prof. Dr. Ulrich S. Schubert
Friedrich Schiller University Jena
Laboratory of Organic and Macromolecular Chemistry
Humboldtstr. 10
07743 Jena
ulrich.schubert@uni-jena.de
Phone: +49 3641 9-48201
Fax:      +49 3641 9-48202

Prof. Dr. Andrea Balducci
Friedrich Schiller University Jena
Institute of Technical and Environmental Chemistry
Philosophenweg 7a
07743 Jena
andrea.balducci@uni-jena.de 
Phone: +49 3641 9-48464
Fax:      +49 3641 9-48402

Project Outline

The self-healing of polymers has been studied intensively in recent years. In doing so, general design principles could be established enabling the preparation of healable polymers. As part of the project, these concepts are now to be transferred to functional materials. Specifically, new types of electrodes for use in organic radical batteries or (super)capacitors are to be developed, which are characterized by their ability to heal themselves.

For this purpose, self-healing polymers with various reversible groups are integrated into the electrode materials in order to ultimately enable cracks and damage to be healed. In addition to the synthesis, a focus will be on the characterization of the materials and, in particular, on the investigation of the self-healing properties. On the one hand, the cracks in the electrodes will be examined optically and tactilely, on the other hand, the restoration of functional properties, such as conductivity or capacity, will be analyzed. In particular, a new method will be established with which the healing of functional materials can be quantified in detail. Finally, the project aims to design new self-healing electrodes for applications in organic radical batteries and supercapacitors and to elucidate structure-property relationships for self-healing functional materials.

Principle Investigator

Prof. Dr. Felix Helmut Schacher
Friedrich Schiller University Jena
Laboratory of Organic and Macromolecular Chemistry
Jena Center of Soft Matter
Lessingstr. 8
07743 Jena
felix.schacher@uni-jena.de
Phone: +49 3641 9-48250
Fax:      +49 3641 9-48252

Project Outline

The goal of project 2 is to design nanostructured block copolymer gels for use as electrolytes in polymer-based batteries and electric double-layer capacitors.

These materials also feature self-healing properties, whereby the designed nanostructure additionally enables the restoration of the functional properties after mechanical damage. For this purpose, amphiphilic polyether-based ABC triblock terpolymers will be utilized with a (covalently) crosslinkable block A (furfuryl moieties for Diels-Alder reactions or alkynes for copper-catalyzed azide-alkyne chemistry), a block B being soluble in both organic and aqueous electrolytes providing ion mobility (e.g., poly(methyl glycidyl ether)), and a block C carrying charged repeating units for reversible (non-covalent) crosslinks based on combinations of carboxyl and amino moieties or alternatively, zwitterionic comonomers. The synthesis will be accomplished using a combination of sequential living anionic polymerization of the respective glycidyl ether monomers (i.e. furfuryl or alkynyl glycidyl ether for block A, e.g., methyl glycidyl ether for block B, allyl glycidyl ether ether for block C) followed by side chain modification of the C block using thiol-ene click chemistry to realize the charged repeating units.

The characterization will play an important role in this project starting from the comprehensive analysis of the ABC triblock terpolymers towards the preparation of the respective gels, including investigations of crosslinking efficiencies and probing the stability besides morphological studies. Furthermore, the functionality, i.e. the ionic conductivity, of the gels should be precisely understood with regard to the diffusion of ions, to evaluate the self-healing progress in the end. Finally, the gel electrolytes will be used in test batteries as proof-of-principle for new electrolyte materials.

Principle Investigators

Prof. Dr. Kalina Peneva
Friedrich Schiller University Jena
Laboratory of Organic and Macromolecular Chemistry
Jena Center of Soft Matter
Lessingstr. 8
07743 Jena
kalina.peneva@uni-jena.de 
Phone: +49 3641 9-48790
Fax:      +49 3641 9-48792

Dr. Martin Hager
Friedrich Schiller University Jena
Laboratory of Organic and Macromolecular Chemistry
Humboldtstr. 10
07743 Jena
martin.hager@uni-jena.de
Phone: +49 3641 9-48227
Fax:      +49 3641 9-48202

Project Outline

Organic solar cells have been studied intensively in recent years and the achievable efficiencies have been significantly increased. However, the long-term stability of these systems is still often a challenge. In addition to the photo-oxidation of the active materials, e.g., conjugated polymers, cracks in the active material or delamination of the active layer from the electrodes also play a major role, in particular for flexible solar cells. In this context, this project of the research unit FuncHeal investigates new concepts for self-healing of photoactive materials that are suitable for organic solar cells.

Two damage scenarios will be investigated: i) Mechanical damage in the active layer (donor-acceptor blend) and ii) damage through photooxidation. Through the design and synthesis of tailor-made donor and acceptor materials (from small molecules to polymers), the introduction of flexible groups or reversible groups is intended to achieve mobility of the material on the one hand (healing of cracks) and on the other hand the introduction of reversible groups to enable the exchange of chromophores (healing after photooxidation). These processes will be examined in detail in the pure donor materials as well as in the blend with appropriately adapted acceptor materials.

Principle Investigators

PD Dr. Harald Hoppe
Friedrich Schiller University Jena
Laboratory of Organic and Macromolecular Chemistry
Humboldtstr. 10
07743 Jena
harald.hoppe@uni-jena.de
Phone: +49 3641 9-48995
Fax:      +49 3641 9-48202

PD Dr. Martin Presselt
Leibniz Institute of Photonic Technology
Albert-Einstein-Str. 9
07745 Jena
martin.presselt@leibniz-ipht.de 
Phone: +49 3641 206-418

Project Outline

The stability of polymer solar cells, in which at least one component of the photoactive layer is a conjugated polymer, is often studied as a function of the illumination spectrum, temperature (cycles), humidity, and influence of reactants such as oxygen or water. In addition, attention is paid to long-term stable mixing of electron donors and acceptors, which is referred to the morphological stability.

In particular for potential real applications, the flexible properties of organic solar modules are important, which, however, places increased demands on their mechanical stability. Due to the bending of solar modules that occurs during application, cracks in the active layer as well as detachment of the active layer from the charge extraction layers (or electrodes) can occur. The latter process is called delamination and it occurs when the adhesion between two layers is unsatisfactory, while cracks within a layer indicate insufficient cohesion. P4 is, therefore, dedicated to the prevention of cracks and delamination defects, as well as to their healing. The material systems are based on the donor / acceptor materials provided by a different project or on classical poly(3-alkylthiophenes) in combination with fullerene derivatives and later also non-fullerene acceptors. The photoactive layer also consists of at least ternary mixtures to be able to map the required properties. To investigate healing, films and solar cells on flexible substrates are stretched or bent, respectively, to provoke cracking and delamination. The defects created by the mechanical stress are characterized and quantified by microscopic and spectroscopic methods. After the healing, an analogous procedure is performed enabling a quantification of the healing.

Principle Investigator

Prof. Dr. Stefanie Gräfe
Friedrich Schiller University Jena
Institute of Physical Chemistry
Helmholtzweg 4
07743 Jena
s.graefe@uni-jena.de
Phone: +49 3641 9-48330
Fax:      +49 3641 9-48302

Project Outline

Self-healing materials are very interesting for many applications due to their ability to repair structural damage and, thus, to regain their mechanical stability and properties. For self-healing functional materials, in addition to the structural repair, ideally the functionality should also be recovered. The design of such materials is very challenging and can benefit from computational studies of the self-healing process and of the functionality down to the molecular level.

In this context, a large toolset of theoretical and simulation methods will be applied in this project to understand the degradation and recovery of various self-healing functional materials. The employed methods cover a range of relevant spatial and temporal scales: From larger-scale dynamical processes and structural properties (molecular dynamics and molecular mechanics calculations) to the molecular level (quantum chemical and hybrid quantum chemical-molecular mechanical calculations). The systems of investigation are chosen in close collaboration with the experimental projects of this research unit.

The overall objective of the project is the modelling and exploring the underlying mechanisms leading to degradation, thereby aiding the synthesis-oriented projects in identifying possibilities either to avoid degradation or to regenerate the material and the functionality. In particular, spectroscopic observables will be simulated such as UV/vis, Raman or 2D-correlation spectra which are used in the experimental investigations of self-healing processes. Eventually, general structure-property relationships will be revealed for functional self-healing materials which can help aiding the design of those materials.

Principle Investigators

Prof. Dr. Benjamin Dietzek-Ivanšić
Friedrich Schiller University Jena
Institute of Physical Chemistry
Helmholtzweg 4
07743 Jena
benjamin.dietzek@uni-jena.de
Phone: +49 3641 9-48360
Fax:      +49 3641 9-48302

Prof. Dr. Jürgen Popp
Institute for Physical Chemistry (IPC)
Friedrich Schiller Unviversity of Jena
Helmholtzweg 4
07743 Jena
juergen.popp@uni-jena.de
Phone: +49 3641 9-48320

Project Outline

Project 6 will characterize the molecular mechanism in self-healing materials for energy conversion and storage by means of multimodal frequency- and time-resolved optical spectroscopy. The experiments will provide insights into the complete lifecycle of a functional self-healing material from damage to healing. In doing so, the project will gain a detailed understanding of the molecular processes occurring during healing of functional materials For polymer-based batteries and supercapacitors as well as organic solar cells.

To this end, the project’s focus is threefold:

• Investigation of the molecular structure changes during degradation and self-healing via in-situ vibrational spectroscopy and vibrational spectroelectrochemistry in combination with 2D correlation analysis to derive structureproperty relationships with respect to the underlying reversible self-healing chemistry;
• Studying transport and chemical reactivity to provide a molecular view on the diffusion and thus self-healing processes of the self-healing functional materials researched within FuncHeal, by combining fluorescence and non-linear Raman microscopy. Here, the molecular view will be correlated with macroscopic healing studies to enable tuning the molecular components inside the materials to achieve the desired macroscopic properties and
• Characterizing excited-state processes in damaged and healed materials for energy conversion to validate the light-induced function-determining process in self-healing materials for polymer solar cells. Furthermore, the project strives towards utilizing the spectroscopic signature of optically excited polymer materials to generate metrics to follow the kinetics of material degradation and healing.