UNIVERSITY OF COLOGNE

Our research begins with molecular design. We develop structurally precise chiral π-conjugated systems where molecular geometry and electronic structure are intrinsically linked. Through modern synthetic strategies, we build molecules that translate three-dimensional chirality into measurable optical and electronic function.

Rather than treating chirality as an accessory, we place it at the centre of molecular design.

A major focus of our work is understanding how chirality governs light–matter interactions in both ground and excited states. Using circular dichroism and circularly polarized luminescence spectroscopy, we uncover how subtle structural changes influence chiroptical response, emission behaviour, and excited-state dynamics.

These insights guide the development of new molecular systems with high optical anisotropy.

By integrating molecular design with photophysical characterization and device-oriented collaborations, we develop chiral functional materials for advanced optoelectronic applications. Our research explores circularly polarized emitters and related systems that may enable more efficient photonic devices and simplified device architectures.

This interface between chemistry and device physics allows us to translate molecular innovation into technologically relevant directions.

Over the past century, the chemistry of diimide-fused planar PAHs and helicenes has advanced largely in parallel. In this project, we aim to unite these two fields to address key challenges in chiral organic semiconductors. While [n]helicenes are known for their strong chiroptical response, their charge-transport and emissive properties remain limited. To overcome these shortcomings, we design helicenes functionalized with six-membered imide units at both termini of the conjugated backbone, combining the chiroptical strength of helicenes with the favorable electronic and emissive features of diimide chemistry.

References: 
Angew. Chem. Int. Ed. 2025.  DOI: 10.1002/anie.202508779
Chem. Commun. 2023.  DOI: 10.1039/D3CC04470J
SynLett, 2021. DOI: 10.1055/a-1616-5643
J. Am. Chem. Soc., 2020. DOI: 10.1021/jacs.0c11053

Efficient chiral emitters are poised to revolutionize CP-OLEDs (OLEDs with circularly polarized (CP) electroluminescence) by enabling the direct generation of CP light, thereby eliminating the need for external polarizers or quarter-wave plates. This not only increases brightness but also simplifies device architecture, thereby enhancing energy efficiency and enabling more flexible displays. Moreover, the narrowband emission is crucial for high color purity, reduces spectral overlap in multi-emitter designs, and improves device efficiency and contrast. Together, these features make molecules with narrowband CP luminescence (CPL) highly attractive for next-generation displays and spin-optoelectronic devices.

We exploit the multi-resonance effect of a 1,4-azaborine (B,N) core to combine the strong chiroptical response of helicenes with the narrowband, high-efficiency photophysics of B,N-functionalized PAHs. Our synthesis yields configurationally stable, enantiopure helicenes with B,N motifs at defined positions. These molecules exhibit exceptionally narrow fluorescence and CPL (FWHM 17–28 nm; 0.07–0.13 eV) and high photoluminescence quantum yields, overcoming the broad emission and large Stokes shifts of conventional helicenes. One compound in this series exhibits the narrowest CPL reported for an organic emitter to date, highlighting strong potential for hyperfluorescent architectures and CP-OLED integration.

References:
 J. Am. Chem. Soc. 2024. DOI: 10.1021/jacs.4c11404
Angew. Chem. Int. Ed., 2023. DOI: 10.1002/anie.202218965J