B3
Electronic coupling in inorganic/organic semiconductor hybrid structures for optoelectronic function
Objectives
- Fundamental understanding of the electronic processes in HIOS relevant for optoelectronic applications.
- Development of strategies for tuning structural and electronic properties of HIOS to optimize coupling of optical excitations amongst the constituents, and ultimately, to achieve their hybridisation.
- Elaboration of design schemes to implement HIOS in opto-electronic/photonic devices for light/laser emission, optical nonlinearity and light-electrical energy conversion.
In order to benefit from complementary properties of organic and inorganic semiconductors in HIOS, efficient coupling of electronic excitations amongst the constituents is a prerequisite. This includes excitonic coupling as well as charge transfer across the inorganic/organic interface. A goal of the project consists in the elaboration of a thorough understanding of the fundamental physics governing electronic coupling amongst organic and inorganic semiconductors.
To achieve HIOS with advanced optoelectronic or photonic function, the transfer processes need to be tailored. For light-emitting applications, efficient incoherent coupling between “inorganic” Wannier-Mott excitons and “organic” Frenkel excitons is required, while exciton dissociation at the inorganic/organic interface needs to be suppressed. On the other hand, exciton dissociation and separation of charges is the basic step in applications targeting at light-electrical energy conversion. Strategies will be worked out (in collaboration) and tested to shape organic and inorganic subcomponent as well as the interface such to optimize the required transfer process. The ultimate goal is the realisation of coherent coupling between the two exciton species corresponding to the creation of a new type of optoelectronic excitation.
To incorporate HIOS in optoelectronic devices we will follow two approaches: Due to low-temperature epitaxy of ZnO, sandwich-type HIOS with the organic material embedded within the inorganic semiconductor can be prepared. Alternatively, hybrid optoelectronic devices can also be based on organic/inorganic p-n junctions combining n-type inorganic semiconductors with p-type conjugated molecules which are either nominally undoped or doped with electron accepting molecules. Charge carrier injection and transport in HIOS is a so far largely unexplored field. This project will contribute to fill this knowledge gap.
