Controlling delocalisation and funnelling of excited state energy in the strong coupling regime in molecular systems

Introduction

A fundamental physical property of matter is its ability to interact with light. This is not only the basis of fascinating concepts like seeing colors, but also the foundation of life and advanced technologies. Yet, some basic physical laws hamper possible utilizations. It is therefore of great importance to examine how to bend these laws, how to bypass them, and by so doing open up new opportunities for novel applications. This is exactly what this project aims to do.

Light-Matter Interaction

Plant leaves are green because they absorb visible light. However, it is less known that this light-matter interaction can be enhanced to the point where it is so strong that the photon and molecule cannot be regarded as separate entities, but as a combined system with unique properties.

Nature uses strong pigment-pigment interactions to rapidly funnel absorbed sunlight to the photosynthetic reaction center. However, up to now, organic solar cells do not take advantage of such quantum processes to enhance light to electricity conversion.

Project Objectives

In CONTROL, I will use a chemical viewpoint to develop unique molecules optimized for strong light-matter interactions. With these, I will examine excited state processes of strongly coupled systems. My aim is to:

1. Funnel excitation energy to charge transfer states in an organic heterojunction using the delocalized nature of hybrid light-matter states.
2. Enable transport of excitation energy over distances much longer than have been previously considered feasible.

Methodology

Using time-resolved optical spectroscopy and photoconductivity, I will systematically analyze the interaction between delocalized hybrid states and localized charge transfer states, allowing design criteria to be formulated.

Expected Outcomes

The outcome of this research program will be the description and mechanistic revelation of a novel quantum physical phenomenon that can enable the development of organic solar cells from simple layered structures with unprecedented efficiencies.