A new Doktorate

Abhilash has passed the doctorate exam today!
Congratulations to Abhilash!

Micellar coupling enables the synthesis of organic semiconductors in water, at room temperature and under standard oxygenated atmosphere

Researchers at the University of Milano Bicocca optimized a protocol for the synthesis of different classes of both molecular and polymeric organic semiconductors enabling the use of water as the sole solvent. Reactions are efficient and do not require heating or atmosphere control. The process is based on the use of a commercially available surfactant (Kolliphor EL) enabling the formation of micelles not easily permeated by oxygen. Such association colloids provide nanoreactors where water insoluble materials can accumulate and react, eventually to be expelled in the water phase directly in the crystalline form.
Examples of semiconductors accessible through such route include diketopyrrolopyrroles (used in OPV), perylene and naphthalenediimides (osed in OFET) and polyfluorenes (relevant for OLEDs). The research unit is now extending the protocol to the preparation of thermosensitive materials pertaining to the class of the latent pigments.

Reference: Mattiello, S. et al., 2017. Suzuki–Miyaura Micellar Cross-Coupling in Water, at Room Temperature, and under Aerobic Atmosphere. Organic Letters, 19(3), pp.654–657.

PCAM / Thinface Workshop at Jagiellonian University Cracow

PCAM / Thinface Workshop in Cracow – Faculty of Physics, Astronomy and Applied Computer Science

Advanced topics in physics and materials engineering: PCAM in Cracow
18-19 May 2017.

Program
List of participants
(small changes in list, absent: Sigitas Tamulevicius and Jyrki Heinamaki )

It was a very fruitful meeting in Krakow, foreseeing new collaborations between Jagiellonian University (UJ) and SDU-MCI, as well as UJ and entire PCAM/Thinface network.
 
New collaboration partners in the medical community in Cracow, namely Department of Medical Physics (Dr. Hab. Ewa Stepien) and Department of Physics of Nanostructures and Nanotechnology (Prof. Marek Szymonski). The former collaboration mainly between SDU and UJ, targeting innovative imaging technique of Nano and micro cellular vesicles. The later especially interesting for the MONET ITN application for the next round of application.
Another possible collaboration between SDU-MCI and UJ, Department of Solid State Physics (Prof. Franiszek Krok), in direction of organic nanofibers and plasmonics.
The ongoing collaboration between SDU-MCI and Atomic Optics Department, UJ (Dr. Tomasz Kawalec) and possible future direction were also discussed.
The Dean of Physics at UJ and Prof. Kozubski have been interested in being more closely related to PCAM –by exchanging students or working on a joint binational doctorate.

Molybdenum-oxide hole transport layers for organic electronics

At SDU NanoSYD, University of Southern Denmark, reactive sputtering of Molybdenum oxide thin-films are conducted in order to develop metal-oxide films with tunable opto-electronic properties. By controlling the flow of oxygen during the sputtering process, it has been demonstrated that the composition of the resulting films, and thus also the optical and electrical properties can be tuned from transparent to opaque, and from conductive to insulating, respectively. In addition, by conducting a UHV annealing step following growth, it is possible to crystallize the films, leading to large change in work function of the films. In a recent publication, the researcher demonstrate that its possible to vary the work function by almost 2 eV, reaching values close to those of single crystalline Molybdeum oxide (6.9eV). The high work function films can be developed on device relevant substrates, which therefore makes them highly relevant as transport layers in for example photovoltaic devices, which is pursued as the next step by the researchers.

• A. L. F. Cauduro, R. dos Reis, G. Chen, A. K. Schmid, H.-G. Rubahn and M. Madsen, “Work Function Mapping of MoOx Thin-Films for Application in Electronic Devices”, Ultramicroscopy, doi.org/10.1016/j.ultramic.2017.03.025 (2017)
• A. L. F. Cauduro, R. dos Reis, G. Chen, A. K. Schmid, C. Méthivier, H.-G. Rubahn, L. Bossard-Giannesini, H. Cruguel, N. Witkowski and M. Madsen, “Crystalline Molybdenum Oxide Thin-Films for Application as Interfacial Layers in Optoelectronic Devices”, ACS Appl. Mater. Interfaces, 9, 7717 (2017)

Formation of porous silicon on silicon microcantilevers

At University Autonoma de Madrid the role of PSi on the silicon microcantilevers has been emphasized for the development of nanomechanical interfaces as biosensors. The new bimodal mechanical-optoplasmonic system for biosensing was demonstrated performing a sandwich assay for the detection of  a Prostate Specific Antigen (PSA).

Microcantilevers are the most simple and widely used nanomechanical biosensing systems. The resulting mechanical response to their interaction with a biological analyte is either a deformation (static mode) or a resonance frequency shift (dynamic mode) as a consequence to the added mass of the analyte on the sensor surface. The formation of porous structures on microcantilever sensors is of interest because of the influence of the increased surface area in a wide set of physical and chemical parameters. Indeed, the formation of PSi on silicon microcantilevers allows combining the advantages of both forms of Si. The crystalline Si provides excellent elastic and mechanical properties while PSi provides large adsorption surfaces and constitutes an excellent biofunctional material. Additionally, porosification implies an initial surface activation, which can be redirected to induce an organosilane functionalization of the surface.
In this work, we used p-doped crystalline Si chips with 8 cantilevers per chip (Fig. 1 SEM images of a Micromotive chip).

To generate PSi, electrochemical etching is the most widespread method. However, in the case of cantilevers, due to their fragility, small size, and the absence of metallic contact, we performed vapor phase stain etching. This technique does not require any technical equipment such as current source and consists of exposing the Si substrate to acid vapors issued from a mixture of HNO3 and HF (Fig.2). To start the process and initiate the formation of brown NOx vapors, a piece of sacrificial Si is added to the solution. The chip, stuck on a Teflon lid, is exposed to the vapors once the reactions reach a steady-state.


Figure 2. Vapor phase stain-etching formation of PS on Si cantilever.


Figure 3 shows the microcantilever surface modification after the vapor phase stain etching using a mixture HNO3:HF (1:1) and exposing the chip to the acid vapors for 20s. The microcantilevers have an initial width of 1 μm.

The role of PSi on the silicon microcantilevers has been emphasized for the development of nanomechanical interfaces as biosensors. Indeed, the significance of this new bimodal mechanical-optoplasmonic system for biosensing was demonstrated performing a sandwich assay for the detection of PSA (Prostate Specific Antigen), a prostate cancer biomarker.

Chloé Rodriguez

Horst-Günter Rubahn receives Fyens Stiftstidende’s Researcher Prize

for being a leader in nanotechnology.

Every year, Fyens Stiftstidende awards a prize to researchers from SDU who have excelled in their field. This year, the prize went to Professor Søren Askegaard from the Department of Marketing & Management; Head of Research Jane Clemensen from the Department of Clinical Research; and Head of Department Horst-Günter Rubahn from the Mads Clausen Institute.

“Horst-Günter Rubahn has had a pivotal role in the field of nanotechnology, both as a leader or a participant in countless national and international research projects and in networks with universities, research institutes and companies. This is reflected, for instance, in his position on the editorial board of ‘Reports on Progress in Physics’ – which is one of the most influential review journals in physics – and his selection as the Danish expert in nanotechnology to the EU’s committee for new European research grants in nanotechnology and material physics,” were some of the things written about him in his nomination/recommendation.

Tomographic analysis of organosilane modified PSi

The controlled wetting of porous silicon surfaces by self-assembly of organosilanes is one of the main objectives of the project “ESR04: Humidity effects at the organic/porous silicon sensor interface”. Organosilane-modified porous silicon prepared at UAM has been characterized by focused ion beam tomography and scanning electron microscopy at CIC nanoGUNE. The tomographic analysis has allowed to individualize permeable and impermeable structures as a function of organosilane end group. The use of contrast agents has permitted to image dendritic pore growth. These results are relevant from the point of view of volumetric vs surface functionalization of porous silicon-based sensors.

Image: FIB tomography of porous silicon stained with phosphotungstic acid. The pores are filled with the stain; each pore is colored separately. The dark green system is 4 micron in height and 0.750 micron wide.

Movie:  FIB tomography slice of ca. 10x4x4 micron

Collaborators in this project are: Chloe Rodriguez and Miguel Manso, UAM, Madrid Alexander M. Bittner and Andrey Chuvilin, CIC nanoGUNE, Donostia-San Sebastian Evgenii Modin, National Research Centre “Kurchatov Institute”, Kurchatov Sq. 1, Moscow, Russia

New building for organic electronics in Dresden

After more than 100 years in the old Beyer-Bau, the IAPP (Dresden Integrated Center for Applied Physics and Photonic materials) moved to a new building. The all new Hermann-Krone-Bau is named after Hermann Krone, a photographer, researcher and university teacher closely related to the beginnings of IAPP.

The new building offers more than 3400 square meters and will host IAPP, parts of the Institut für Angewandte Physik (IAP) and the Center for Advancing Electronics Dresden (cfaed), the excellence cluster of TU Dresden, and the Hermann-Krone-Sammlung, a collection of historic photographies, negatives and scientific texts related to the development of photography.

In 27 cleanrooms of ISO class 6 and 8 distributed over 1000 m2 it is possible to produce organic electronic devices in dust free conditions. Additionally low vibration lab space was created to improve the conditions for people working with scanning microscopy. Overall, the conditions to produce and characterize organic electronic devices have improved significantly with the new building.

When everything is finished organic solar films will be installed on the southern facade of the building to test the building integration of organic photovoltaics in an EE-EFRE funded project.

At the IAPP we will use the new facilities to design organic devices (OLED, OSOL, OTFT), organic (doped) thin films and we will work on new materials for organic electronics. For this purpose we have several vacuum sublimation chambers and the instrumentation to electrically and optically characterize samples (UPS, XPS, temperature dependent transmission spectroscopy, impedance spectroscopy, Seebeck effect and conductivity measurements…).

Read about the inauguration ceremony here.
Bernhard Nell

New organic PV project launched at MCI, SDU

MCI, SDU is lead partner of a new project that focus on improving the stability of organic solar cells. The project CompliantPV, launched in January 2017, is funded by in total 6 MDKK from the Villum Foundation, and aims to target the stability of flexible organic solar cells and improve at the same time both the photo-oxidative and mechanical stability of flexible solar cells by introducing specially formulated stabilizing compounds into the active layers in the cells.

The project will ultimately lead to flexible solar cells with drastically improved lifetimes, which is an important step in the further development of the technology. The project is led by the Organic Photovoltaics group at NanoSYD, MCI, SDU, and conducted in close collaboration with the Danish Technical University, Chemical Engineering (Prof. Anne Ladegaard Skov) and the Department of Chemistry at Aarhus University (Prof. Peter Remsen Ogilby) in Denmark.

The image displays a solar cell lifetime setup with multiple sample holders that support in total 50 organic solar cell substrates illuminated by a solar simulator and measured continuously for lifetime analysis. The sample holders are loaded in a glovebox that contains only Nitrogen.

For further information, please contact:
Associate Professor Morten Madsen, madsen@mci.sdu.dk
Dr. Vida Engmann, engmann@mci.sdu.dk

New hole transport layers for PV technology developed at MCI, SDU

Thin, crystalline films of Molybdenum oxide with very high work function have recently been developed at MCI, SDU. The films are formed through a reactive sputtering process that has the advantage of controlling the precise compositions of the films via tuning of the oxygen partial pressure during the growth process. The researchers at MCI, SDU has together with researchers at UPMC, Paris and the LBL facility at Berkeley demonstrated that rapid UHV annealing of the reactively sputtered films can lead to a large increase in the work function, which makes them highly relevant as hole contact layer in optoelectronic devices, for examples in new PV technology. The findings are published in the journal ACS Applied Materials and Interfaces in Feb 2017 (DOI: 10.1021/acsami.6b14228), where details on the correlation between the nanoscale structure and the electronic properties of the films are provided, which is the first time such a correlation is detailed for these metal-oxide films.