Environmental influence on light-induced processes

• Applicant: Professor Dr. Bernd Engels
• Subject Area: Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: from 2012 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 207601309

The work of the last period can be separated into several parts. We developed a new aggregatebased approach and could use it to clarify the mechanisms how excimers are formed in perylenbased systems, either aggregates or crystals. This work was performed with project P5 (Engel) and P7 (Pflaum). We worked out several approaches for the prediction of excitondiffusions lengths (Overlapapproach, Marcus theory, Levich-Jortner together with project P6 (Dyakonov/Deibel). The codes were implemented into the program package VAMP and used to investigate the accuracy of these approaches if only quantum chemically computed parameters are used. For the overlap approach the deviation to the experimental data are less than 10%. The Marcus-theory largely underestimates the exciton diffusion lengths are is very useful because it is considerably less expensive. In addition we developed approaches which are useful for the characterization of the potential energy surfaces of large molecule. They were implemented into the CAST program package and used to investigate the influence of the environment on photo-induced processes in cooperation with P1 (Würthner), P2 (Lambert) and P3 (Brixner). The goals of the next period can be divided into three parts. In the first part the approaches developed in the last period shall be improved and tested using the Cyclophane-PBI compounds which were synthesized and experimentally investigated by P1 and P2. Additional tests will be performed for crystalline DIP and PTCDA. The experimental data about these systems were delivered by P7. In the second part of our work we will investigate interfaces which will be prepared by P7. The last part of our work is devoted to the development of improved force fields for fullerenes and PBIbased compounds. All these developments will be employed for a design of PBI-derivatives which possess specific aggregate properties.

• DFG Programme: Research Units
• Subproject of: FOR 1809: Light-induced Dynamics in Molecular Aggregates
• Major Instrumentation: Clusterserver mit Rechenknoten
• Instrumentation Group: 7000 Datenverarbeitungsanlagen, zentrale Rechenanlagen