Tallinn University of Technology

TalTech recognised its researchers for the best research articles of 2019 in three different fields.

In Natural, Exact and Health Sciences:
SANDRA KAABEL, ROBIN S. STEIN, MARIA FOMITŠENKO, IVAR JÄRVING, TOMISLAV FRIŠČIĆ, RIINA AAV ‘Size-Control by Anion Templating in Mechanochemical Synthesis of Hemicucurbiturils in the Solid State’, Angewandte Chemie International Edition 2019, 58, 6230–6234

The self-organisation of molecules is one of the most intriguing phenomena in chemistry. While the formation of macrocycles and molecular cages in dilute solutions has been relatively well-studied, the scientific community’s understanding of the self-organisation of molecules in a solvent-free environment is very limited. This article describes the first example of self-organisation of molecules into macrocycles of different sizes by template molecule and in solvent-free conditions. By applying acid catalysis, mechanochemistry, and spontaneous reorganisation of oligomers targeted by anionic template molecules, solid phase 6- and 8-unit hemicucurbiturils with a quantitative yield were synthesised. The synthesis method developed is very efficient and environmentally friendly, as it allows the formation of up to 32 carbon-nitrogen bonds in a single step, using 100 times less strong acids in the same reaction compared to the existing synthetic method in the presence of a solvent. Developing new efficient and environmentally friendly synthesis methods is important because it provides access to large-scale molecular container synthesis. The latter are applicable to the study of environmental monitoring, materials, and biological systems.

In Technics and Technology, the two best were chosen:
ANTON VEDEŠIN, JOHN MEHMET ULGAR DOGRU, INNAR LIIV, SADOK BEN YAHIA, DIRK DRAHEIM ‘A Secure Data Infrastructure for Personal Manufacturing Based on a Novel Key-less, Byte-less Encryption Method’, IEEE Access, 2019

We have entered an era with 3D printers where anyone can be the creator of a new product. This means the emergence of new business models in which small and medium-sized enterprises can locally serve a wide range of industries with high quality and speed.

The company of the first author of the article, Anton Vedešin – 3D Control Systems – is developing 3DPrinterOS cloud technology, which can be used to perform 3D printing indirectly. If you previously needed to design in a drawing software program and take other steps to print, which also increased your cybersecurity risk, this technology aims to move from an idea to a physical object with a single click. The platform also allows you to ‘translate’ the 3D image for different printers to understand. While 3D printing is very convenient today, the focus of Vedešin and his co-authors Dogru, Liivi, Yahia, and Draheim is on how to securely communicate with tens of thousands of printers. This is made possible by so-called encryption without keys and bytes, where a hash function is used to send a hash message and technology can combine messages in different layers. This means that the printer does not receive all the information at once, and messages about the item being printed arrive at the printer layer by layer.

Launched in 2015, the science- and technology-intensive service has connected 34,000 printers, 1.2 million objects have been printed, it has taken nearly 400 years of printing time and 41 tonnes of material, and the platform has 100,000 users. These include many well-known educational institutions, such as Yale, Harvard, or Duke University. The company’s technology is licensed by Boch and Kodak.

KRISTI TIMMO, MARE ALTOSAAR, MARIS PILVET, VALDEK MIKLI, MAARJA GROSSBERG, MATI DANILSON, TAAVI RAADIK, RAAVO JOSEPSON, JÜRI KRUSTOK, MARIT KAUK-KUUSIK ‘The effect of Ag alloying of Cu2(Zn,Cd)SnS4 on the monograin powder properties and solar cell performance’, Journal of Materials Chemistry A, 2019, 7, 24281–24291 DOI:10.1039/C9TA07768E

Increasing energy consumption and the resulting increase in CO2 emissions are a growing burden on the environment. Therefore, the prevention of harmful climate change and the development of affordable energy supplies are becoming more and more a priority. New technologies that are cleaner, greener, faster to implement, and more responsive to local requirements have been one of the great challenges of technological development in the last decade.

Solar energy meets all these criteria. Theoretical calculations show that with the use of sophisticated four- and five-component materials, it is possible to fabricate solar panels with a conversion efficiency to electric energy of approximately 30%. Research work at the Tallinn University of Technology’s Laboratory of Photovoltaic Materials and the Laboratory of Optoelectronic Materials Physics has focused on compounds called kesterites.

The current problem in solar cells made from these absorber materials is the lack of open-circuit voltage relative to the exclusion zone value for these materials. There are also many deep defects and defect clusters in kesterites that are detrimental to the efficiency of the solar cell. One way to reduce such defects is to replace Cu (or Zn) with isoelectronic chemical elements that have a larger covalent radius, e.g. Ag. Photoluminescence spectroscopy and spectral analysis confirmed that partial replacement of Cu with silver increased the width of the exclusion zone of the absorber material, which also increased the VOC value of the solar cell. The small addition of silver also improved the value of the short-circuit current.

In Social Sciences and Humanities:
MAARJA TOOTS ‘Why E-participation systems fail: The case of Estonia’s Osale.ee’, 2019 Government Information Quarterly, 36 (3), 546−559

Over the past 15–20 years, many countries have experimented with online participatory platforms that allow citizens to have a say in policymaking. In practice, however, e-participation channels often fail to generate an active user base and achieve the expected qualitative results. This award-winning article examines the causes of failure of e-participation platforms by proposing an analytical model that combines research literature on information systems management and e-participation.

The model views failure as a process of intertwining unfavourable contextual factors, stakeholder expectations and needs, and project management problems. The empirical analysis of the article also provides important lessons from the experience of the Estonian government’s participatory portal Osale.ee, which could help other countries avoid mistakes in developing e-democracy.

This article has been partially supported by the Estonian Research Council’s Personal Research Funding PUT773 ‘Public Sector Innovation: The Case of Modern Identity Management Technologies’.