Chemistry of (Bio)organic Materials and Devices
Kees (J.C.) Hummelen was born in Groningen, The Netherlands. He received his MSc in Chemistry and a cum laude doctorate degree in Science under the mentorship of Hans Wynberg at the University of Groningen in 1979 and 1985, respectively. After four years of playing jazz (piano) and art video production, he spent two years as a post-doctoral fellow with Fred Wudl at UCSB. He is the inventor of PV material PCBM and a co-author of the seminal 1995 Science publication on the discovery of the bulk heterojunction solar cell (> 7000 citations in WoS). Kees was appointed full professor in chemistry in 2000 in Groningen. He is the leader of the Dutch national FOM Focus Group “Next generation organic photovoltaics”. The last 20 years, his main research activities were in fullerene chemistry and the development of organic solar cells. Other research topics are materials for organic electronics and molecules for single-molecule electronics. Kees is among the highest cited scientists in materials science (Thompson, 2015). Since 2013, he is CEO of Solenne BV, Groningen, the fullerene company that he co-founded in 2005.
Albert Polman is scientific group leader at the NWO Institute AMOLF in Amsterdam, the Netherlands, where he heads the Program “Light management in new photovoltaic materials”. He is professor of Photonic materials for photovoltaics at the University of Amsterdam. Polman obtained his Ph.D. from the University of Utrecht, was post-doctoral researcher at AT&T Bell Laboratories and then became group leader at AMOLF, where he also served as director from 2006-2013. He spent sabbaticals at Caltech (USA) and UNSW (Sydney).
Dissipative self-assembly of gold nanoparticles driven by carbodiimide fueled transient anhydride formation - Kushagra Gahlot
The conventional equilibrium self-assembly leads to the thermodynamically stable structures but on the contrary, most processes in biological systems are dissipative in nature. The synthetic analogues of these dissipative systems are rare. Here, we are trying to investigate the transient assembly of colloidal nanoparticle system driven by a chemical fuel. The system remains assembled until the fuel is consumed after which the backward reaction i.e. hydrolysis overcomes to form a disassembled state. This cycle can be induced multiple times with injection of a new fuel. This design provides more insight into the out of equilibrium assembly of colloidal structures and how we can manipulate it by employing different stimulus bringing us one step closer in understanding the dissipative processes at work in nature.
Quantitative analysis of uptake rates of inorganic NPs into Cells using fluoresence Microscopy - Christian Pöpsel
Nanoparticles for biomedical applications, especially their potential use as drug carriers, have been in the focus of research for several years. Despite the fact, that nowadays many possible pathways of internalization have been reported, the mechanism of the nanoparticle uptake is not yet completely understood. Other than most works, which focus solely on the amount of internalized nanoparticles, in this study the aim was to differentiate between the three processes of adhesion to the cell membrane, desorption and internalization of nanoparticles. In order to study the kinetics of those three mechanisms, which all contribute to the nanoparticle uptake, fluorescence microscopy was used. Since a previous work with HeLa Cells and 40nm PS-COOH nanoparticles indicated, that all three of these processes are rather rare events, a more efficient method based on a short exposure of the cells to a high concentration of nanoparticles rather than a continuous exposure at low concentration was developed.
Synthesis and thermoelectric properties of inverse hybrid perovskites - Ruben Hamming-Green
Hybrid perovskites have been researched heavily in the last decade as possible materials for solar cells and thermoelectrics. The presence of an organic molecule inside the perovskite structure has proved to significantly alter its characteristics, for example through improving photon absorption for photovoltaics. The rotational freedom of the molecules scatters phonons, which is favorable for low thermal conductivity in thermoelectric materials. However, current hybrid perovskite structures are unstable when exposed to environmental conditions. A proposed new class of perovskites, inverse hybrid perovskites, may be more resistant to environmental degradation due to the tight coordination of the organic cation with an anion. Furthermore, their band gaps are predicted to be tunable over a wide range from metals to insulators. The attempted synthesis of (CH3NH3)3SeI, which has recently been proposed to be a thermodynamically stable structure, will be reported.
Perovskite rare-earth nickelates (RENiO 3 ) displays a sharp paramagnetic metal-to- antiferromagnetic insulator transition, accompanied by an orthorhombic-to- monoclinic phase transition - Mohammad Alimoradi
Metal-to-insulator transition in rare-earth nickelates (RENiO3, where RE=Nd, Sm, Eu) have been appealing recently for studying the electron-lattice coupling in strongly correlated systems. In this project, I was provided with epitaxial NdNiO3 thin films with different thicknesses (2-20 nm) grown on single crystal NdGaO3 substrates by pulsed laser deposition (PLD). We investigated the influence of thickness and substrate on the transport properties, including resistance, metal-insulator transition temperature (TMI) and thermal hysteresis, of NdNiO3 thin films. By comparing these results with those previously obtained in the group for the same material grown in LaAlO3 subtrates, we confirmed that the conduction behavior of NdNiO3 thin films is highly sensitive to the choice of substrate: The thin films grown on NdGaO3 substrates not only exhibit a higher TMI but also show a slight dependence on film thickness, whose origin can be traced back to the epitaxial strain induced by substrate.
Tuning the Intermolecular interactions in DNA-PEG Supramolecular complex: a SAXS study - Atul
The highly charged polyanionic nature of nucleic acid molecules like DNA needs nonspecifically bound cations, such as Sodium and Magnesium, to neutralize the negative charges on their backbone. The inter-DNA interactions can thus be effectively modulated in the presence of monovalent and divalent ions. Recently, the formation of a thermally stable DNA duplex in the complete absence of metal cations in water has been achieved. In this small research project, we aim to study the interaction and conformation of these novel DNA complexes in the total absence of metal ions. Moreover, we plan to employ metal cations as decomplexing agents of the DNA-PEG supramolecular complex and follow the detachment of PEG from the DNA backbone. The study will be conducted using mostly solution small-angle X-ray scattering (SAXS) scattering, and a suitable mathematical model for the DNA-PEG complex will be developed to elucidate the structure and interaction potential in these systems.
Degredation of ternary organic solar cells - Panagiotis Christodoulis
Photostability is a major factor that needs to be taken into account before the commercialization of any competitive solar cell. Organic solar cells have long suffered from poor stability. Ternary blends, with an active layer of three components have been increesingly studied as a means of improving the well studied binary solar cells. In many systems tarnary blends have already surprassed thier corresponding binary vases but a general rule has yet to be established as the trend strongly varies with each system. Herein, the photostability of the ternary system PBDB-T:ITIC:PCBM is studied and the physical phenomena that cause it are investigated. Vasrious samples with varying concentration ratio between ITIC and PCBM are fabricated and the ratio 0.7:0.3 is highlighted as the best combination of efficiency and stability. Therefore, the physics of degradation are studied for this highlited system and as well as the two binrary cases PBDB-T:ITIC and PBDB-T:PCBM for comparison.
Understanding the kinetics of uptake and liposome degradation inside cells - Karolina Tran
Liposomes are enclosed lipid bilayers, used as drug carriers since 1960s. Since then liposomes of many different properties were studied, and a number of them has reached the market.
In this project two types of liposomes which showed very different uptake kinetics were studied in order to understand the differences in their intracellular behavior and fate, one made with anionic dioleoylphosphatidylglycerol, DOPG and the other with zwitterionic dioleoylphosphatidylcholine, DOPC.
In order to explain the different kinetics, flow cytometry was used to disentangle uptake from intracellular degradation and determine the contribution of energy dependent processes and eventual passive diffusion. The results suggested that DOPG enters cells with higher efficiency followed by a fast intracellular degradation, giving rise to a drop in the uptake kinetics. On the contrary DOPC shows low uptake and higher stability, thus a linear increase in uptake followed by an apparent saturation, more closely resembling the kinetics of non-degradable nanomaterials.
Studying the intracellular trafficking of nanoparticles using cellular fractionation - Armin Kiani
Understanding the cellular behavior of nanomedicines is of paramount importance in designing enhanced delivery systems. However, the details of the intracellular trafficking of nanoparticles once they are internalized by cells are not completely defined. In this study, we used a recently developed method based on flow cytometry to isolate and characterize intracellular organelles from cells exposed for different times to fluorescent nanoparticles. This allowed us to map the time-resolved intracellular trafficking of nanoparticles in different organelles and compare the outcomes for nanoparticles of different sizes. Accumulation into the lysosomes was monitored by labeling these organelles with a specific antibody (LAMP1). In addition, we followed trafficking of nanoparticles of different colors inside the same organelles and determined the number of nanoparticles per organelle over time. The results suggest that multiple nanoparticles can be trafficked inside the same organelles however many organelles remain with only one or few nanoparticles even 24 hours after uptake.
Composition engineering in mixed tin and lead perovskite solar cells - Eileen Zhu
The power conversion efficiency (PCE) of lead (Pb)-based hybrid perovskite solar cells (PSCs) has been remarkably boosted from 3.8% to 22.1%. Despite the outstanding achievements, the toxicity of lead causes wide concerns about the large-scale industrialization of this new type of solar cell. Additionally, the optical bandgap of lead based PSCs is far from being the optimum. A solution to these issues could come from tin (Sn), however, the state-of-art of mixed tin and lead perovskite solar cells has a record PCE of about 17%, much lower than the 22% of the pure lead based perovskite solar cells. This project aims for improving the PCE of the mixed tin-lead perovskite solar cells. We first engineered the molar composition of tin and lead in the mixed tin-lead perovskite film. After the optimization of the tin and lead ratio, the effects of mixed cation and mixed halide on the performance of the mixed tin-lead perovskite solar cells were studied.
Gating molecular junctions fabricated by nanoskiving - Eelco Tekelenburg
Current available lithography technology is expensive and is limited to tens of nm resolution. For fabricating truly nanoscale devices, new approaches are needed. In this study molecular sized junctions are fabricated using nanoskiving, in which a self-assembled monolayer is sandwiched between two evaporated electrodes. Nanoskiving is a form of edge lithography in which thin sections are cut using an ultramicrotome equiped with a sharp diamond knife. In this way a high throughput and low cost fabrication method is developed. The goal of this project was to fabricate these molecular junctions which could be gated to make a large area molecular transistor. Further we can use the wide range of organic molecules that can be designed to match the application in electronic circuits.
Quantum-classical dynamics simulation of a dimer to study if it can be used as a Molecular MotorAtreya Majumdar
Natural molecular motors play a major role in mechanical motion within many biological pathways. But it was not until 1999 when Feringa et. al. synthesised the first artificial molecules that can undergo unidirectional rotation with the input of energy.This kind of motor along with other forms of molecular machines like shuttles, valves etc. can lead to a revolution in Nanorobotics. The rotation of Feringa motors has two major components- a photoisomerization around a pi-bond followed by a thermally activated helical inversion. The latter being the rate-determining step. We propose an alternative molecular system where the rotation is around a sigma-bond wherein dipolar coupling of chromophores are utilised to shape the excited state energy surface and achieve the rotation using light as the only input and avoid the thermal step altogether. In this computational study, we employ quantum-classical methods to study the dynamics of such a system and explore if the principle works and if it is efficient enough for practical use.
Modification of Tobacco Mosaic Coat protein to study the self-assembly - Edwin Schreuder
The capacity of viruses to spontaneously self-assemble into highly ordered structures has been exploited for a wide variety of applications, from the development of drug delivery systems to the templated synthesis of nanostructured materials. The assembly of the Tobacco Mosaic Virus (TMV) into a tube-like structure is known to be determined by the hierarchical self-organization of a single coat protein unit. The aim of this work is to direct the assembly of azobenzene-coupled TMV coat proteins onto polymeric cyclodextrin matrices, in order to obtain artificial switchable viral structures with tunable size and shape.
Determining the lipid-derived physical properties of a model system for PC-3 derived exosomes - Cat Saunders
Single particle techniques are increasingly being applied to study the physical properties of bioassemblies. Recently developed nanoindentation experiments using atomic force microscopy (AFM) can give information about heterogeneity between individual particles in a sample. An added benefit is that near to physiological conditions can be simulated since experiments are performed in liquid. One such system which can be studied with this method is extracellular vesicles, which have attracted significant interest recently for diagnostic, drug delivery and therapeutic applications. Here, the method and latest results are presented for a study using artificial liposomes as a model system to investigate the mechanical properties of PC-3 derived exosomes.
Molecular Dynamics simulations on the bending of a self-assembled artificial muscle - Josse Muller
The recent demonstration of an artificial muscle is an exciting example of the possibilities of hierachically self-assembled molecular motors. The reversible switching of single molecules was used to generate movements in a centimetre-long fiber, which consists for 95 wt% of water. However, it is challenging to experimentally study the working mechanism of such assemblies on all length scales. An alternative approach, taken in this study, is the use of molecular dynamics to model the system, which can lead to new insights into its operation. We created a coarse-grained model of the self-assembled amphiphilic molecular motor and studied its assembly into fibers and the impact of the switching of the molecular subunit on the assembly. Coarse-graining allows the investigation of larger systems and longer length scales than is feasible using atom-scale models.
Light management and the dream of photovoltaic energy for 0.01 €/kWh
With over 2000 km2 of solar panels generating 300 GWp worldwide, photovoltaics is becoming an important source of energy for our society. The efficiency of solar energy conversion using single-junction semiconductor solar cells has now reached 27% for silicon and 29% for GaAs. However, so far no material has reached the Shockley-Queisser efficiency limit of 34%. I will discuss recent developments in photovoltaic materials technology with a focus on how improved light management can lead to efficiencies beyond the SQ limit and can reduce costs, with the ultimate goal to generate solar electricity at a cost of 0.01 €/kWh.