Modelling the electronic structure of single-doped perylene

The molecule perylene has exciting applications in the fields of organic electronics and astronomy

New York | Heidelberg, 15 April 2025

The molecule perylene has become of great interest to scientists developing organic electronics and technology which harnesses organic molecules or polymers with electronic properties like conductivity. Perylene has uses ranging from the creation of organic semiconductors to organic light-emitting diodes (OLEDs) to even building organic solar cells. In addition to this, perylene is of great interest to astronomers, as this molecule has been discovered in interstellar gases and nebulae, granting insights into the powerful cosmic events that forged and dispersed it.

While the ionisation energy and electron affinity of perylene are well studied experimentally, little is theoretically known about the electronic structure of a single doped perylene molecule. “Doping” refers to the process of adding impurities to intrinsic semiconductors to alter their properties, so a better understanding of doped perylene may enhance its usefulness in organic electronics.

New research published in EPJ B by authors including Marcel Rodekamp of the Universität Regensburg looks at the electronic structure of a single doped perylene molecule, modelling perylene’s π electrons using the Hubbard model and by performing ab initio or “from the start” grand-canonical Monte Carlo simulations.

“While the description of perylene with the Hubbard model and extensions is a widely used approach, to the best of our knowledge, no one has attempted a first-principles Monte Carlo simulation of the (undoped) molecule,” Rodekamp says. “Doping introduces additional complications that render the usual algorithm infeasible. Our innovation was to change the algorithm, bringing previously intractable problems within reach.”

The team’s work focused on the single-particle spectrum, which refers to the energies resulting from a system's response when an electron is attached to it. From a non-interacting perspective, this energy increases linearly with the chemical potential, which controls the doping, but this provides an incomplete picture.

“Once we take interactions into account, electrons repel each other, and this picture is too simple. With our new methods, we could identify chemical potentials where perylene gains additional charges, while taking the interactions into account,” Rodekamp continues. “Furthermore, we could study how the single-particle spectrum changes with the chemical potential, confirming that the non-interacting picture was too simple.”

The team is currently working on a reliable scale-setting procedure that will provide a value for the Hubbard interaction that allows a direct comparison to experiment.

“We are excited to see where our new algorithms can take us. Since the simplest one was able to tackle perylene so successfully, we are eager to investigate even larger molecules,” Rodekamp concludes.

Reference: Rodekamp, M., Berkowitz, E., Gäntgen, C. et al. Single-particle spectrum of doped C₂₀H₁₂-perylene. Eur. Phys. J. B 98:36 (2025). https://doi-org.ezproxy.uniagraria.edu.co/10.1140/epjb/s10051-024-00859-1