Subwavelength molecular opto-electronic devices based on plasmonic nano antennas

• Applicants: Professor Dr. Bert Hecht; Professor Dr. Jens Pflaum
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2015 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281419165

We propose a new approach to organic light emitting diodes (OLEDs) based on the integration of an ultrathin layered functional molecular architecture into subwavelength resonant plasmonic nanoantennas. The metallic nanoantenna not only enhances light emission but at the same time serves as a stable electrical contact for charge carrier injection. The power of the concept arises from the fact that the key functions of such a hybrid organic/metallic opto-electronic device, comprising charge-carrier injection into a molecular architecture, radiative charge-carrier recombination, as well as finally, the excitation of plasmons and emission of photons, become tightly integrated into a single subwavelength nano-electro-optical system. The nanoantenna design determines the radiation pattern, emission polarization, exciton lifetime and spectrum resulting in a fundamental control over the photon emission process and its dynamics. Further functionality can be integrated into such a nano-pixel by electrically addressing different antenna regions. Fig. 1 summarizes the vision of this proposal showing a single-crystalline antenna structure on top of ultrathin organic transport and recombination layers and a single-crystalline gold bottom contact. Our approach may open new perspectives for OLED size, efficiency, lifetime and radiation characteristics as well as for new electrically pumped plasmonic hybrid devices in general. Possible applications of such electrically-driven subwavelength photon sources lie e.g. in the field of display technology utilizing very small pixel dimensions to provide improved image quality and, in future, to accommodate e.g. goggle-free 3D technologies or to realize semitransparent displays. Our approach will also open new perspectives for unconventional nonclassical light sources operating in the telecom spectral region, and, by proper management of losses, e.g. by using dark resonances, it may be possible to enter the strong-coupling regime to study electrically-pumped exciton-polariton physics and low-threshold lasing. To realize the proposed concept we synergistically combine the expertise of two experimental groups. The Hecht group is specialized in single-crystalline nano-antennas and plasmonics. The Pflaum group is experienced in organic semiconductors and their implementation in thin-film opto-electronic devices.

• DFG Programme: Research Grants