Welcome
To The GreenEnergyMaterials-Series
Our Mission
The Green Energy Materials Series (GEMS) aims to promote the work of emerging and established scientists in the field of renewable energy covering subjects such as photovoltaics, energy storage, green fuel production, and more!
With its seminar series, GEMS gives the stage to early career researchers and key players in the field to promote and discuss their work with a community of green energy enthusiasts. The series provides a platform for scientists to give feedback, hear about new trends, current challenges, and important techniques and insights.
This series aims to facilitate discussions and to enable deeper insights into phenomena and characterisation techniques. As such, presentations will focus on clearly defined topics covered in depth rather than a list of big achievements.
Presentations will be around 30 minutes long, with copious time for questions. The series will run online via Zoom once every month. Sessions usually start at 4.30pm Berlin time (GMT+1) but might vary depending on the speakers’ location.
With the speakers’ permission (an embargo period is possible), the talks will be recorded and uploaded to the GEMS YouTube channel.
We look forward to welcoming all of you to these events,
Vincent M. Le Corre | Simon Kahmann | Bowen Yang
Next Talks - 21 January 2026
Paul Drude Institute and University of Potsdam, DE
Organic solar cells have recently exceeded 20% power-conversion efficiency, prompting a key question: how much further can we push performance? Despite rapid advances, progress is limited by photophysical loss channels that are not yet described within a unified framework. At the heart of the problem lies the intricate excited-state dynamics at the donor–acceptor interface, where excitons, charge-transfer states and fully separated charges are in constant interconversion, governed by the materials’ energetic landscape. A central challenge is to understand and mitigate loss pathways involving singlet and triplet charge-transfer states and local triplet excitons, which ultimately constrain the open-circuit voltage. This talk will outline recent insights into these processes and discuss how mastering them could unlock the next efficiency gains in organic photovoltaics.
In this talk, we share our experimental data and kinetic model that, for the first time, explicitly incorporates the formation and re-splitting of local triplet excitons. Fully parameterised by the interfacial energy offset, this unified framework reproduces key photovoltaic observables – such as the charge-generation efficiency, photoluminescence, electroluminescence and the Langevin reduction factor. Our results show that ~the~ triplet-state dynamics may govern device performance. In systems with short triplet lifetimes, triplet decay emerges as the dominant recombination pathway, reconciling long-standing experimental findings, including those in benchmark systems like PM6:Y6. In systems with long triplet lifetimes, triplets can be recycled to mitigate this loss channel. The model further offers a mechanistic explanation for the empirically observed link between energy offset, radiative singlet-exciton decay and reduced-Langevin recombination ~as well as a correlation~, and accurately predicts the device efficiency across different material systems.
By connecting excited-state kinetics with macroscopic device metrics, our work provides a unified mechanistic picture of the photophysics in organic semiconductors.
Eswaran Jayaraman
SDU Centre for Advanced Photovoltaics and Thin-film Energy Devices (CAPE), DK
Sheet-to-Sheet and Roll-to-Roll Processing Large-Area Organic Photovoltaics and Their Lifetime Performance
In recent years, there have been notable successes in commercializing organic photovoltaics (OPV) for new applications. In the laboratory, their power conversion efficiency has exceeded 20% on the cell level using the spin-coating technique. However, the still relatively low performance for large OPV modules, with limited thermal and light stability, has remained a bottleneck for wider adoption. We focused on using a Sheet-to-Sheet and Roll-to-Roll compatible slot-die coating method to fabricate organic photovoltaic cells and modules in ambient conditions, achieving performance similar to that of spin-coated devices. The compatibility of the coating technique was studied across different OPV architectures by fabricating devices using a commercially available Indium tin oxide transparent electrode. The long-term thermal stability of different OPV architectures was studied to identify the degradation pathways. Additionally, we showed long-term light-soaking stability for over 800 hours. Further, to unlock the full Roll-to-Roll compatibility, we adopted a hybrid approach that combines the advantages of R2R vacuum and solution coating methods for fabricating organic solar modules on glass and flexible polyethylene terephthalate (PET) in a top-illumination configuration. The opaque bottom electrodes were developed using R2R sputtering to achieve low sheet resistance and reduced surface roughness. The remaining layers in the devices, including the top transparent silver nanowire (AgNWs) anodes, were optimized using an R2R-compatible slot-die coating method at ambient conditions with greener solvents. We achieved the best PCE of 11.5 % for an ITO-free flexible mini-module. We believe our findings will pave the way for the development of greener, low-cost, and stable organic photovoltaics.
In the Offing
21 January
Safa Shoaee
Eswaran Jayaraman
18 February
Eva Unger
Hayley Gilbert
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