CRC 951/3: Design of Functional Molecular Building Blocks for Covalent and Non-Covalent Assembly at Semiconductor Surfaces (SP A03)

The overarching goal of this synthesis project was and is the creation of high quality, functional HIOS with unique characteristics that – in part – are governed by the structures of the custom-designed molecular building blocks. During the current funding period, we synthesized a variety of molecular building blocks to preparestructurally and compositionally well-defined HIOS. In particular, we were able to develop routes to conjugated organic molecules with defined inherent molecular properties, such as optical gap and oxidation/reduction potentials, and utilized the introduction of dipoles as well as of anchoring groups to direct their assembly, primarily on ZnO surfaces, using physisorption and chemisorption, respectively. Furthermore, photoswitchable molecules that undergo large changes in their dipole moments as well as frontier molecular orbital levels were developed and incorporated into HIOS and related opto-electronic and plasmonic functional structures and devices. In the upcoming funding period, we aim at combining optimized photoswitchable molecules with twodimensional semiconductors, primarily monolayers of transition metal dichalcogenides (TMDCs) to create new hybrid functionalities and devices.
First Subproject “Photoswitchable Molecules”: A variety of photoswitchable molecules, most notably dihydropyrenes, will be developed to exhibit maximum dipole changes as well as HOMO/LUMO level changes, and also to allow for convenient optical switching. Special attention will be given to tune excitation wavelengths, quantum yields, thermal half-life, and fatigue resistance in order to maximize the performance of these molecular HIOS building blocks.
Second Subproject “Surface Attachment”: New routes to covalently assemble conjugated organic molecules, and in particular the optimized photoswitchable molecules, to TMDCs will be developed. Key will be the design of suitable linking moieties, which allow to attach the photoswitches in a specific orientation, in particular to Project A03 (Hecht) 64 orient their dipole moments and thus maximize their Coulomb interactions with the TMDCs upon light-triggered switching.
These directions will be followed in collaboration with A08 (N. Koch), A12 (C. Koch), and A14 (Franke), concerning the structural and electronic characterization of the prepared HIOS. Insights into resulting specific HIOS elemental functions, such as hybrid excitations and their dynamics, will be gained together with B03 (Blumstengel), B07 (Neher), B09 (Stähler), B15 (Bolotin) and B17 (Ernstorfer/Wolf). Feedback from theory will further aid our understanding of molecular and surface chemistry and their interaction to translate molecular switching events to overall HIOS property changes. Based on these insights, prototypical HIOS devices will be fabricated with B14 (List-Kratochvil) and B07 (Neher).

Principal Investigators
Hecht, Stefan Prof. (Details) (Organic Chemistry and Functional Materials)

Duration of Project
Start date: 07/2019
End date: 06/2023

Research Areas
Physical Chemistry of Solids and Surfaces, Material Characterisation

Last updated on 2021-04-08 at 13:57