AA4 – Energy and Markets



Simulation and Optimization of Integrated Solar Fuels and Photovoltaics Devices

Project Heads

Sven Burger, Bernd Rech

Project Members

Felix Binkowski (ZIB) 

Project Duration

01.05.2019 – 30.04.2022

Located at



The energy supply network needs to go through tremendous change in order to meet the demands to mitigate climate change. To achieve this, every aspect of the supply chain must be carefully evaluated and optimized. A cornerstone of any sustainable energy network will be solar energy. While conventional solar cells are rapidly increasing their penetration into energy markets, the requirement of electricity networks to provide on demand power is at odds with the intermittent supply of solar cells.


Solar fuel devices are able to convert solar energy directly into usable fuels, thus storing the energy and allowing distribution through existent networks. Of the various fuels which can be created using photo-chemistry, hydrogen, obtained from water splitting, is the most prominent candidate due to the abundant, low-cost supply of water. Therefore, a better understanding of solar-driven water splitting and developing the technology for water splitting on a large scale is a central challenge facing the transition to a green economy.


Optical device design is an important problem for both of these technology steps: One of the limitations of both currently available PV technology and the developing solar fuel technologies is insufficient absorption of light due to reflective losses, transmissive losses and parasitic absorption. In order to overcome these challenges, optical modelling will play a crucial role. Proper light management in many photovoltaic devices has already lead to large increases in efficiency, typically through the use of periodic nanostructures. However, there exist multiple areas for which current models are insufficient. Amongst many others, specifically, efficient, rigorous models for isolated scatterers and for isolated sources in periodic media are needed.


This project develops and investigates rigorous methods to treat light scattering problems, especially also problems including isolated sources and scatterers in periodic media. Further the developed methods are applied to investigate multiscale effects in topical energy storage and photochemistry devices and to optimize their performance, in direct collaboration with physicists, chemists and engineers of Helmholtz Zentrum Berlin für Energie und Materialien (HZB) and with external collaboration partners.


Isolated sources appear, e.g., in quantum dot upconversion materials which are combined with periodic nanostructures. In order to simulate light scattering of isolated sources in such environments we use high-order FEM to simulate Maxwell’s equations in a subtraction field formulation. Localized sources are modeled here as periodic dipole sources. In order to build a non-periodic model of the source in the periodic medium, a summation is performed where the phase of the emitted field is varied over the Brillouin zone. A regular, cartesian sampling of this phase distribution has been shown to be inefficient as it requires too many fields before it converges, due to typically present singularities in Bloch space. Therefore cartesian sampling results in too large computation times. We develop adaptive approaches for sampling the Brillouin zone.


Research results of this project include investigations of theoretical models for light matter interaction [1, 2, 3, 4, 5, 6, 7, 8] as well as their applications to surface chemistry and photocatalysis [9, 10, 11, 12], as well as optimizations for energy-efficient light emitting devices [13, 14, 15], for photonic upconversion devices [16, 17], and for photovoltaic devices [18, 19]. The images below show visualizations of field distributions in nanoscale devices some of which are realized experimentally at HZB.

Selected Publications

  1. A Riesz projection based method for nonlinear eigenvalue problems, F. Binkowski, et al., J. Comput. Phys. 419, 109678 (2020)
  2. Quasinormal mode expansion of optical far-field quantities, F. Binkowski, et al., Phys. Rev. B 102, 035432 (2020)
  3. Modal analysis for nanoplasmonics with nonlocal material properties, F. Binkowski, et al., Phys. Rev. B 100, 155406 (2019)
  4. Modal expansion of optical far-field quantities using quasinormal modes, F. Binkowski, et al., EPJ Web Conf. 238, 05007 (2020)
  5. Quasi-normal mode expansion as a tool for the design of nanophotonic devices, R. Colom, et al.,  EPJ Web Conf. 238, 05008 (2020)
  6. RPExpand: Software for Riesz projection expansion of resonance phenomena, F. Betz, et al., SoftwareX 15, 100763 (2021)
  7. Efficient hybrid method for the modal analysis of optical microcavities and nanoresonators, T. Wu, et al., J. Opt. Soc. Am. A 38, 1224 (2021)
  8. Bayesian optimization with improved scalability and derivative information for efficient design of nanophotonic structures, X. Garcia Santiago, et al., J. Light. Technol. 39, 167 (2021)
  9. Hot Electron Generation through Near-Field Excitation of Plasmonic Nanoresonators, F. Binkowski, et al., ACS Photonics 8, 1243 (2021)
  10. Hot electrons generated in chiral plasmonic nanocrystals as a mechanism for surface photochemistry and chiral growth, L. Khosravi Khorashad, et al., J. Am. Chem. Soc. 142, 4193 (2020)
  11. Long-and short-ranged chiral interactions in DNA-assembled plasmonic chains, K. Martens, et al., Nat. Commun. 12, 2025 (2021)
  12. Field Heterogeneities and Their Impact on Photocatalysis: Combining Optical and Kinetic Monte Carlo Simulations on the Nanoscale, M. Hammerschmidt, et al., J. Phys. Chem. C 124, 3177 (2020)
  13. Axial localization and tracking of self-interference nanoparticles by lateral point spread functions, Y. Liu, et al., Nat. Commun. 12, 2019 (2021)
  14. Nanopatterned Sapphire Substrates in Deep-UV LEDs: Is there an Optical Benefit?, P. Manley, et al., Opt. Express 28, 3619 (2020)
  15. Tripling the light extraction efficiency of a deep ultraviolet LED using a nanostructured p-contact, E. Lopez Fraguas, et al., Sci. Rep. 12, 11480 (2022)
  16. Double-layer metasurface for enhanced photon up-conversion, P. Manley, et al., APL Photon. 6, 036103 (2021)
  17. Progressive self-boosting anapole-enhanced deep-ultraviolet third harmonic during few-cycle laser radiation, L. Shi, et al., ACS Photonics 7, 1655 (2020)
  18. Improved Quantum Efficiency by Advanced Light Management in Nanotextured Solution-Processed Perovskite Solar Cells, P. Tockhorn, et al., ACS Photonics 7, 2589 (2020)
  19. Nano-optical designs enhance monolithic perovskite/silicon tandem solar cells toward 29.8% efficiency, P. Tockhorn, et al., Nat. Nanotechnol. 17, 1214 (2022)

Selected Pictures

Image: Visualization of the electromagnetic field distribution in a silicon nano-resonator.

Image: Plasmonic resonance in a metal nano-wire.

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