Materials scientists at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have achieved a new record in the performance of organic non-fullerene based single-junction solar cells. Using a series of complex optimisations, they achieved certified power conversion efficiency of 12.25 percent on a surface area measuring one square centimetre. This standardised surface area is the preliminary stage for prototype manufacture. The results achieved in conjunction with partners from the South China University of Technology (SCUT) have now been published in the renowned journal ‘Nature Energy’.
Organic photovoltaic systems have undergone rapid development during the last few years. In most cases, organic solar cells consist of two layers of semiconductors – one acts as the donor by supplying the electrons, and the second acts as an acceptor or electron conductor.
In contrast to the silicon conventionally used, which must be drawn from a melt or precipitated in vacuum systems, the polymer layers in this system can be deposited from a solution directly on a supporting film.
On the one hand, this means comparably low manufacturing costs, and on the other, these flexible modules can be used more easily than silicon solar cells in urban spaces.
For a long time, fullerenes, which are carbon-based nanoparticles, were considered ideal acceptors, however the intrinsic losses of fullerene-based composites still severely limit their potential efficiency.
The work carried out at FAU has thus resulted in a paradigm shift. ‘With our partners in China, we have discovered a new organic molecule that absorbs more light than fullerenes that is also very durable’, says Prof. Dr. Christoph Brabec, Chair of Materials Science (Materials in Electronics and Energy Technology) at FAU.
The significant improvements in performance and durability mean the organic hybrid printed photovoltaics are now becoming interesting for commercial use. However, to develop practical prototypes, the technology must be transferred from laboratory dimensions of a few square millimetres to the standardised dimension of one square centimetre.
‘Significant losses frequently occur during scaling’, says Dr. Ning Li, a materials scientist at Prof. Brabec’s Chair. During a project funded by the German Research Foundation (DFG), Ning Li and his colleagues at SCUT in Guangzou were able to significantly reduce these losses.
In a complex process, they adjusted the light absorption, energy levels and microstructures of the organic semiconductors. The main focus of this optimisation was the compatibility of donor and acceptor and the balance of short-circuit current density and open-circuit voltage, which are important prerequisites for a high output of electricity.
Certified record efficiency
‘I think the best way to describe our work is by imagining a box of Lego bricks’, says Li. ‘Our partners in China inserted and adjusted single molecular groups into the polymer structure and each of these groups influences a special characteristic that is important for the function of solar cells.’
This results in a power conversion efficiency of 12.25 percent – a new certified record for solution-based organic single-junction solar cells with a surface area of one square centimetre, where the acceptor does not consist of fullerenes.
It is also interesting to note that the researchers succeeded in keeping the scaling losses to such low levels that the highest value in the lab on a small surface was only marginally under 13 percent. At the same time, they were able to demonstrate a stability relevant to production under simulated conditions such as temperature and sunlight.
The next step involves scaling up the model to module size at the Solar Factory of the Future at Energie Campus Nürnberg (EnCN) before development of practical prototypes begins.
Prof. Dr. Christoph J. Brabec
Phone: +49 9131 8525426
‘Fine-tuning of the chemical structure of photoactive materials for highly efficient organic photovoltaics’, Nature Energy: doi: 10.1038/s41560-018-0263-4
Dr. Susanne Langer | idw - Informationsdienst Wissenschaft
New molten metal hybrid filters from TU Freiberg will make components even safer and more resistant in the future
28.02.2020 | Technische Universität Bergakademie Freiberg
KIST researchers develop high-capacity EV battery materials that double driving range
24.02.2020 | National Research Council of Science & Technology
Researchers at the University of Bayreuth have discovered an unusual material: When cooled down to two degrees Celsius, its crystal structure and electronic properties change abruptly and significantly. In this new state, the distances between iron atoms can be tailored with the help of light beams. This opens up intriguing possibilities for application in the field of information technology. The scientists have presented their discovery in the journal "Angewandte Chemie - International Edition". The new findings are the result of close cooperation with partnering facilities in Augsburg, Dresden, Hamburg, and Moscow.
The material is an unusual form of iron oxide with the formula Fe₅O₆. The researchers produced it at a pressure of 15 gigapascals in a high-pressure laboratory...
Study by Mainz physicists indicates that the next generation of neutrino experiments may well find the answer to one of the most pressing issues in neutrino physics
Among the most exciting challenges in modern physics is the identification of the neutrino mass ordering. Physicists from the Cluster of Excellence PRISMA+ at...
Fraunhofer researchers are investigating the potential of microimplants to stimulate nerve cells and treat chronic conditions like asthma, diabetes, or Parkinson’s disease. Find out what makes this form of treatment so appealing and which challenges the researchers still have to master.
A study by the Robert Koch Institute has found that one in four women will suffer from weak bladders at some point in their lives. Treatments of this condition...
The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.
Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...
Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.
Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...
12.02.2020 | Event News
16.01.2020 | Event News
15.01.2020 | Event News
28.02.2020 | Materials Sciences
28.02.2020 | Life Sciences
28.02.2020 | Architecture and Construction