Community Research and Development Information Service - CORDIS

Final Report Summary - OSC-GO (Organic Solar Cells - Go!)

Organic solar cells (OSC), a part of the larger emerging field of organic electronics, have the potential to become a very cheap, large area and flexible photovoltaic technology that can in principle scale up fast to terawatt in installed capacity. However, to tap their potential, many questions on the scientific fundamentals need to better understood. The underlying theme of this project is advance the understanding of OSC and making OSC become a reality. To achieve this goal, the project had three main strands of research: molecular p- and n-doping of organic semiconductors, structure-property relationships, and degradation mechanisms of OSC. To address these fundamental questions, the research was based on highly purified small molecules, molecular doping technology, and the excellent control of vacuum processes for the deposition of thin organic films. These are the same technologies that made commercial organic light emitting diodes (OLEDs) a reality, and recent results for OSC point in a similar direction, showing that this unique approach not only allows for solid fundamental studies, but also world record OSC.
During the 48 months of this project, Dr Riede established a laboratory with equipment for our research from scratch and his research group consists now of eight members (5 PhD students, 2 PostDocs and the PI) working on various aspects of OSC. While this CIG supported a wide range of activities to get his group established, their main research focus so far has been on the determination of structure-property relationships, as the electrical and optical properties of any kind of OE device strongly depend on the molecular arrangement and microstructure in the active organic layers. For probing how the molecules arrange in thin films, they have been using light of various wavelengths, from X-rays to near-infrared light, which can tell e.g. about the predominant distance between molecules and the average cluster size. These results were complemented with data from device characterisation, e.g. how well an OSC performs under sunlight. One of their speciality is that they can now monitor how the molecules arrange during the deposition process.
The structure-property research was supported by their investigations into molecular doping of organic thin films and the stability of our devices. Molecular doping of organic semiconductors has similar advantages as p- and n-doping in inorganic semiconductors, which has been key their commercial success. Dr Riede’s research group has been investigating the transition from efficient doping to non-doping in organic semiconductors, something that is important both for the development of novel organic dopants and their use in OE devices. Finally, the commercial viability of OSC is only given if their stability meets the needs of their application, which is typically a lifetime in excess of 10 years. To that end, they investigated pathways in OSC depending on the used materials building on our microstructural and optical characterisation expertise of organic thin films as well as data on working OSC (in particular current-voltage characteristics and external quantum efficiency).
The results of their work have been published in international peer-reviewed journals as well as presented at international conferences. Further publications are in the pipeline, e.g. on different microstructural and photochemical degradation paths in the OSC they identified in their experiments.
Of the set objectives, all were reached, but the stretch goal: the demonstration of 20 year stable OSCs with more than 16% efficiency. While latest research including from Dr Riede’s group points towards the possibility of these efficiency values, nobody has yet reached them (the current world record at time of writing this is between 13-14%).
For their research, Dr Riede has been continuously building his network of collaborators and has been working with a growing number of partners from academia (e.g. Prof Natalie Banjeri from the University of Bern/Switzerland and Prof Chris Nicklin from the Diamond Light Source/UK) to industry partners (e.g. Merck Chemicals Ltd/UK and K.J. Lesker Ltd/UK).
For more information, please see their webpage at https://www2.physics.ox.ac.uk/research/afmd-group and follow them on twitter @afmdgroup (https://twitter.com/afmdgroup).

Reported by

THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF OXFORD
United Kingdom

Subjects

Life Sciences
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