CRC 1772/1: Molecular photoisomerization within 2D materials (SP C06)

Project C06: "Molecular photoisomerization within 2D materials"

The aim of the project is to study photoisomerization reactions in confined space at and in between layers of 2D materials and utilize the light-induced changes in the molecular interlayer to remote-control mol2Dmat heterostructures. Light is ideally suited to initiate chemical transformations in mo-lecular layers selectively at a given time and in the wanted location within the confinement of 2D materials. In this regard, molecular photoswitches represent an excellent tool to investigate the in-fluence of spatial confinement on the underlying light-induced unimolecular photoisomerization pro-cess. Key questions of the project relate to how reactivity and selectivity, in particular, related to reversibility and stability (fatigue resistance), can be controlled by confining photoswitches and their assemblies within layered materials (WP1). Successfully integrated photoswitches will be exploited to optically modulate the properties of mol2Dmat heterostructures following three approaches (WP2-4). Specifically, diarylethenes with large variations of their frontier molecular orbital levels will be used to modulate the excitonic insulator phase transition in TiSe2 (WP2). Diarylethenes with large in-plane variation of their transition dipole moments will be designed and used to prepare, alter, and probe collective excitonic states on and in between graphene and hexagonal boron nitride (WP3). Dihydropyrenes and spiropyrans with large changes of their out-of-plane molecular dipole moment will be investigated at and in between transition metal dichalcogenides to guide their photoswitching behavior by applying strong external electric fields (WP4). The intercalated photoswitchable mo-lecular layers should enable the remote optical modulation of optoelectronic and excitonic properties of the mol2Dmat heterostructures with high spatial and temporal resolution.